Monday 3 June 2019

LEARN KRAKATAU (2018) BY ANALOGY TO KRAKATAU (1883)


LEARN KRAKATAU (2018) BY ANALOGY TO KRAKATAU (1883)
                             Sohei Matsuno, Prof. (ret.) of freelance, Dr. (Eng.), Causal Study
                                Advisor on Technical Affairs at Jamilla Restaurant, Palembang, RI
                                                   E-mail: sohei_matsuno@yahoo.com
                                       Kimora Matsuno (Proofreader), Student, Singapore International School
                                                  Alena Handi (Illustrator), Student, Maitreyawira Palembang School

ABSTRACT

Anak Krakatau Eruption (2018) and Krakatau Eruption (1883) are two of the serial eruptions at the same volcanic complex. Hence, they’re qualitatively analogous, though quantitatively different. The difference is: ‘If the explosive energy stored as compressed steam in a steam-magma chamber broke through its dome in a big quantity, or leaked out through its conduit in small quantities.’ This difference causes difference in consequences, e.g., in scale and interval. Keywords are: ‘the particular settings (shown in this ABSTRACT) on which analogies and differences stand.’ Without the key, no study can open the gate to Krakatau or Sunda Strait. The key can be found by analogy between Krakatau Eruption (1883) and (2018).
It’s been learnt that most of experts consider there’s no other solution to the Sunda Strait tsunami (2018) besides the one that’s been suggested by Coordinating Maritime Affairs Minister. It says, ‘The tsunami was caused by an underwater landslide that was triggered by Anak Krakatau eruption.’ They support it by analogy to Stromboli tsunami (2002) which was caused by landslides, and satellite images that show a loss of land in the SW flank of the volcanic island. The writers herein forward an alternative solution before the parties concerned.

Keywords: shallow magma source, shallow magma chamber, shallow steam explosion

INTRODUCTION

Abbreviations
In this paper abbreviations are shown in ( ) placed after the word when it firstly appears. After that, the abbreviation is used throughout this paper. For instance, in this paper, ‘the 1st writer of this paper’ is abbreviated by a pronoun ‘he’.
Usually used abbreviations, km for kilometer, E for east etc are directly used, e.g., S30°E for ‘from south turn thirty degrees toward the east’.
The ‘Sunda Strait tsunami (2018) is an important consequence of a cause ‘Anak Krakatau Eruption (2018)’. This paper shall focus on the cause rather than the consequence. Hence, Anak Krakatau is a subject in this paper. Further, the Krakatau and Anak Krakatau eruptions in 1883 and 2018 are called Eruption (1883), ditto (2018) as phenomena and Krakatau (1883), ditto (2018) as events. It’s because, if Anak (Child) is used in front of Krakatau, it sounds as if it were newly born. Really, it’s not a birth of new Krakatau but a revival of the old one. Think the reason why the ongoing studies make analogies to other events, e.g., Stromboli (2002), putting Krakatau (1883) aside. He thinks this symptom is partially caused by the name of Anak Krakatau. Differentiating the two by the year of happening, he hopes, the symptom may wane. In this paper, Anak Krakatau is used only as a proper noun.
As for definitions of any causal and logical terms, cf. his past causation study papers, [1] ~ [19].

Particular Characters of Krakatau Eruptions

Particular Settings define particular Characters of Krakatau Eruptions
The Krakatau Complex has particular geophysical-geological-geographical settings as expressed by Keywords in ABSTRACT. As Eruptions (1883) & (2018) happened in the same volcanic complex; they were commonly subjected to these particular causal settings. Then, their consequences must have correspondingly particular characters. This is the backbone of the analogy between the two eruptions. Reversely, the particular settings can be learnt by analogy between the two eruptions.
Because of the particularities, some popular theories and concepts aren’t applicable to Krakatau. They’re being on a trial and error process to reach the truth. But many data of studies do not contradict but agree to the particular settings proposed by him.

A view Point to realize particular settings
Among many, the best one is a historical point of view. That is;
The 1st Krakatau Eruption in human history happened when the former Krakatau erupted in 416 AD. Its edifice collapsed and left a 7-km-diameter pre-1883-Krakatau caldera where three islands remained. One of them was the previous Krakatau Island. 1467 years (yrs) after Eruption (416), Eruption (1883) happened. It reduced the previous Krakatau Island area to 1/3. But the caldera kept its size as it’d been before. The remnant of the previous Krakatau Island is the present Rakata Island. 44 yrs after Eruption (1883), in 1927, underwater steam emissions were observed. Next year, an edifice emerged in the same caldera within the lost territory of the previous Krakatau Island. It’s named Anak Krakatau. 90 yrs since-then are the geological history of Krakatau (2018) in the modern human history. It developed as follows:
It repeated small, intermittent eruptions to build up a sizable volcano. The activity has been intensified since June 2018. During these periods, the elevation (EL) of its summit showed ascent and descent in yearly ~ monthly timescale but in a general trend it was ascent. The ascent is partially due to the accumulation of erupted lava on the edifice and mainly due to the inflation of a chamber by steam brought in and left behind by incoming and outgoing magma. In Oct. 2018, EL reached 338 (m). Then, on Dec. 22 2018, it made a bigger eruptions than usual, having caused tsunamis and lowered its EL to 110 (m) within a few days. It immersed itself in seawater and reduced its volume to 1/3. It’s caused by the chamber’s deflation due to the loss of its steam and magma.
Geological events that result in geographical changes proceed in a geological historic timescale. But the events can exhibit the changes in a human historic timescale, if, only if, the cause of the event exists spatially near from the site of its consequences. It was the case of Krakatau events. In both Events (1883) and (2018), shallow magma activities, were directly under the edifice where the consequences happened.

Reasons why particular Settings exist at Krakatau
The reasons are as follows:
In Fig. 1, black squares show volcanoes in Sumatra & Java. A light orange polyline of two linear segments (he added) show their volcanic front lines. The Sumatra line obliquely intersects the Java line at about 30º. The Krakatau is at the intersection. It’s a point of discontinuity. At any discontinuous point, the nature gives transient (particular) settings. The closed area by a blue curve and a green triangle (both he added) are the scopes where the transient settings show up moderately and remarkably (explained later).
                             Fig. 1 Quakes happened in 2018, Origin: Guardian graphic. UGGS
Many applicable data, Illus., concepts etc, support the particular settings. Fig. 1 is an example of Illus. A conceptual example is [20]. It says:
The Sunda Strait is located in the transitional zone between two different modes of subduction: the Java frontal subduction and the Sumatra oblique subduction. This setting implies that the Sunda Strait region is a key to the understanding of the geodynamic processes involved.’ Further,
This would suggest that the Krakatau volcano differs from the other volcanoes in the area. In summary, questions such as the existence of seismologically active features in the Sunda Strait, their exact locations, their relationship to the opening of the strait and their relationship to the volcanic activity and the stress regime in the area need to be studied in order to better constrain the geodynamic evolution of this region.’
He agrees to the findings and the action plans.
But he disagrees to its premise set up for due studies. There’re factual errors. Among them, the greatest one is of causality between the oblique Sumatra and the effects of Indo-Australian plate. He assumes the N30ºE biased push from the Sumatra-side Australian plate (Sumatra plate) is the cause, and the oblique Sumatra is its consequence. Contrarily, the premise says, ‘Oblique Sumatra is the cause, and all the phenomena in Sumatra & Sunda Strait are the consequences. Any derivatives from this factual error, e.g., the ones quoted below, can’t be true.
A stress tensor, which has been deduced from the individual focal mechanisms of earthquakes of the Krakatau group, shows that the tensional axis is oriented N130øE. This study confirms that the Sunda Strait is in an extensional tectonic regime as a result of the northwestward movement of the Sumatra sliver plate along the Semangko fault zone.
[….] the Sunda Strait is an extensional area which results from the north-westward displacement of the southern block of Sumatra along the Semangko fault system as a consequence of oblique subduction in front of Sumatra.
Remember! ‘Unlike compression-shear strength, tension-shear strength of lithosphere, crust and tephra sediment layers is marginally low. It can’t produce energy to activate Krakatau eruption. Only shear under 3-Dinentional (3-D) compression can do it. The Sunda Strait plate is under a 3-D compression regime. So far as being possessed by the false premise, extension regime, scholars will be still studying hard on the same theme when Krakatau (35??) will have come.

Backdrop of this Study

General
There’s a 4-fold backdrop in Krakatau (2018) studies: viz. (i) stumbling start with unfit statements on Sunda Strait tsunami (2018), (ii) Poor analogy to Krakatau (1883), (iii) presence of particular settings at Krakatau, and the last but the biggest, (iv) ongoing studies’ indifference to the particular settings. Against this backdrop, the studies are badly affected. The above mentioned points are explained one-by-one as follows:

Stumbling start with unfit statement
The initial statement of an authority is, ‘There was neither quake nor tsunami but a full-moon tide.’ The statement was done as neither was detected. It's not strange for the current sensor system not to detect a phenomenon [4] & [19]. For the time being, there’s no system to foreknow tsunami before it happens. It doesn’t matter. But it does matter if the authority tries to make the initial statement be consistent. It explained the fatal wave as, ‘Full-moon tidal wave height was 2 (m), the tsunami wave height was 0.6 (m).’ This statement is motivated to make the effects of tsunami be less than the ones of astronomical tidal wave. The tidal gauges are for astronomical waves (period, 12 or 24 hrs.). They’re so designed to over-damp meteorological waves (period, sec. order). The Sunda Strait tsunami waves (period, 6.6 ~ 9.5 min.) aren’t over-damped but under-damped. How much? It’s gauge-by-gage different. Supposing from the Banten gauge-station data, the real tsunami wave height was 7 times greater than the value in the data sheet. Further, when 1st tsunami wave arrived at the coasts; the astronomic tidal wave had already ebbed down to the mean seawater level (m.s.w.l.). In addition, the astronomical wave height is measured from the Low Water Spring (LWS) by the authority. Really, the data are expressed with LWS as a datum line. cf. Fig. 11. It’s correct when the data are for a navigation purpose. But it’s inadequate for a tsunami study. The wave height should be measured choosing the trough of each wave as a datum line. It’s discussed in the later SECT.

Poor analogy to Krakatau (1883)
Most of researchers who are studying on Sunda Strait tsunami (2018) seem to have accepted a hypothesis that assumes an underwater landslide triggered by an eruption as the cause. They induced the hypothesis by analogy to morphologically far less related events than Krakatau (1883), e.g., Stromboli (2002). There’s a minor opinion that attributes tsunami to an on-ground landslide. The researchers reinforce each hypothesis by satellite images that show a remarkable loss of land in the SW flank of the Krakatau Island, insisting it is due to a landslide. If they’d make analogy to Krakatau (1883), they might not depend on such an imaginary phenomenon (landslide) to explain the tsunami. Their motif is the same. Both are denied later.
Any phenomenon, which doesn’t happen in a big-scale model, never happens in a small-scale model. Reversely, any phenomenon which happens in a small-scale model must happen in a big-scale model. It’s the nature of a model test. Really, in Krakatau (1883), big-scale model, a quake and a landslide hadn’t happen, so it didn’t in Krakatau (2018), small-scale model. Reversely, in Krakatau (2018), a part of edifice sunk in the caldera, so it had in Krakatau (1883).

Existence of particular Settings at Krakatau
Krakatau has particular settings. It’s an undeniable fact. If there’s no particularity in Krakatau, the results of mediocre studies may not be dangerous but useless and wasting money only. Really, Krakatau has particularities. Hence, any solution that doesn’t take them into account is not only useless and wasting money but also dangerous.

Ongoing studies’ indifference to the particular settings at Krakatau
Ongoing studies’ indifference to the particular settings of the Krakatau eruptions is related to 2 factors, viz. (i) Stance to deal with the event. It’s to find the cause of Sunda Strait tsunami (2018), not of Krakatau eruption (2018), and (ii) the process to have reached the hypothesis.
As per the stance, it’s enough for ongoing studies to induce a cause of tsunami. It’s been done by the hypothesis, underwater landslide. Even if it can’t be confirmed by site investigations, it doesn’t matter. It’s not a matter of tsunami but of other study field, Volcano. The matter of importance is, ‘the underwater landslide is not denied.’
In the process to have set up a causal hypothesis, the idea of landslide emerged. It can cause tsunami as proven by Stromboli (2002). Big land losses on the SW flap of Anak Krakatau in satellite images conform to the landslide. No other cause was conceivable. Hence, it’s a sole solution. There’s a minor opinion of on-ground landslide. The difference between major and minor opinions is: the latter knows no on-ground landslide was (as he proves later) but the former doesn’t. The latter also knows: the underwater landslide can’t be denied deductively, but the former can be. En passant, he’s denied the latter inductively as explains later.

That is, for the ongoing studies, the matter of Krakatau is an uncollateralized liability.

The underwater-landslide hypothesis is easy to say but impossible to confirm or deny. The Hypothesis of particular settings at Krakatau is uneasy to say but easy to confirm and impossible to deny. Hint is, ‘learn Krakatau (2018) by analogy to Krakatau (1883). That’s all.

Purpose of this Study
The primary purpose of this study is to induce the right Hypothesis for Krakatau (2018). In its process, it needs to explain Krakatau eruptions’ mechanism that includes the tsunami. Hence, to find eruption’s mechanism is a secondary purpose of this study. Pursuing the mechanism of Krakatau eruptions, this paper also seeks the way to control Krakatau eruption by appropriating its power for an economical, public-nuisance-free, inexhaustible energy source as an alternative to petrol and nuclear ones. To offer a starting point for it is a strategic purpose of this study.

MECHNISM OF PARTICULAR SETTINGS AT KRAKATAU

General
In this SECT., he refers to as many applicable data as possible, most of which, in effect, support the existence of the particular settings. It’s also directly revealed by Krakatau (2018) itself, as reported,Seismicity was dominated by shallow volcanic earthquakes in February 2017.’
Before entering discussions, he displays 3 matters for readers’ better understanding, viz.
(1)   The lithosphere that plays a key role in this SECT. is a 50-km deep layer on which 6-km-deep ocean crust (solid) is. It’s covered by a 600-m deep uppermost layer of tephra sediment (solid). They’re supported by mantle (liquid). In this formation, the lithosphere is a transient layer whose property is, ‘the shallower, the solider.’ For the sake of convenience, he regards its upper 1/3-depth lithosphere as a solid dominant sub-layer and the lower 2/3-depth layer as a liquid dominant sub-layer.
(2)   Sumatra was still connected to Java by land in early Cenozoic time. The Sunda Strait has been formed in late Cenozoic time. As the Sunda strait formation is the base of every dynamic phenomenon, it’s to be explained later.
(3)   In some cases, the Plate Tectonics need revisions when it’s applied to. cf. [4].
Keeping the above in mind, learn the mechanism explained in the next Sub-sect.

Mother of Particular Settings   ------ cross section at Krakatau ------
There’s a plural item of particularity. But all are born by a mother. This study shall start with her, ‘the geological cross section at the Krakatau.’
Fig. 2 shows the cross-section of the Sumatra subduction zone. It suits Sumatra, but doesn’t Krakatau. There must be a different one that meets the particular settings at Krakatau.

Fig. 2 Section of Subduction Zone of Sumatra    Origin: JustinaYan’s Blog
The mechanism of causing particular settings was briefly explained in his past paper [5]. But it was for a limited purpose, i.e., to convince engineers engaged in the Sunda Strait Bridge Project of an unignorable existence of Krakatau. He elaborates it in this paper. It might be at odds with readers’ conventional concept. It’s enough for readers to see the existence of the particularities. The existence itself is easily confirmed by facts. Its mechanism isn’t a compulsory subject.
Fig. 3 shows the proposed current cross-section of intrusion zone at Krakatau after the Sunda Strait formation. It began with a V cut at a southernmost point of a line where then adjacent Sumatra and Java had been connected. It was caused by clockwise rotation of Sumatra relative to Java. A part of the Australian plate in front of the V cut intruded into it like a wedge. It was the beginning of the Sunda strait formation 2 million yrs ago. As there’s no continental crust but mantle of lowered EL in the V-cut space, the Australian mantle-plate runs up on the Eurasian mantle. The run-up stops when it balances with the sink-down. Under this equilibrium, the intruding Australian plate’s EL is higher than it was before intrusion. It doesn’t lower its EL unless otherwise loaded downward, e.g., by surcharge or pull down. It happens in the Sunda Strait formation process as explained next. The wedge action under the trend of Sumatra’s clockwise rotational is the driving power of the Sunda Strait formation. The wedge shaped part of the Australian plate is named the Sunda Strait plate.
                                                                                                                                                                                                                                                     
When the Sunda Strait plate intrudes into the strait, it needs some preparatory works with its adjacent Australian plates at its both sides that subduct at their respective depth and dip angles. They’re many local / small works of compression- & tension-shear, bending etc that accompany respective shallow quakes. Quakes at the entrance and in the strait shown in Fig. 1 enclosed by a blue curve are the ones. Among them, 3 chains of quakes at the E-side of the Sunda Strait entrance are the quakes due to tension-bending cracks on the Sunda Strait plate caused by pull-down force from the Java plate through the inclined lithosphere that joins them. This phenomenon takes place on the W-side of the strait as well. It happens later in the strait because of Sumatra plate’s lesser depth and dip angle than the Java plate’s. Each resulted in the sectional reduction of each lithosphere, and ended up in a cut off at its highest EL. It sparked off a chain action to the N end of the wedge. As the tensile cut needs little energy, there’s no big event. Since then, the both-side lithospheres have handed over their job, compressing the Sunda Strait plate, to the crust-tephra layers on them. The inclined remnant lithospheres subduct with their original parts. The spaces once occupied by them are refilled by quaternary tephra sediment.
Another chain of quakes along the W-coast of Java is due to the thrust between the E-side of the N-ward-advancing Sunda Strait plate and the static crust-tephra layers of Java side. There’s neither big seismic nor volcanic event because of little friction. A lubricator is quaternary tuffs of tephra. As a quaternary tuff hasn’t yet been enough consolidated, it’s easily bentonitized when exposed to dry (by sun) and wet (by rain).  It’s called 1st-step withering. As the wet bentonite makes a surface be slippery, it causes troubles in constructions. In the interaction between Java and Sunda Strait plates, the repetition of dry (by friction heat) and wet (by seawater) bentonitizes tuffs. The wet bentonite soaks down into the boundary-section between the conflicting plates, and plays a role of lubricant. Along the W-side of Sunda Strait, no quake is seen. It’s because of the clockwise rotation of Sumatra and richer existence of tuff. This phenomenon is also the reason why Sunda Strait plate’s wedge action has smoothly made the Sunda Strait as it is now. Blind / active strike faults at both sides of Sunda Strait plate are named Matsuno Fault (E) & ditto (W).
In this context, it’s right to say, ‘the strait is locally in tension.’ But it’s wrong to say that the strait is under a tension regime. There’s no tension regime throughout the Sunda Strait. It’s a 3-D compression regime.

Legend: a: Seawater, g: Magma generation, b: Krakatau, h: Magma chamber, c: Upper segment layer, d: Lower ditto, j: 1/3-depth lithosphere sub-layer (sub-layer), e: 2/3- ditto, f: Continental crust, i: Australian plate mantle, k: Eurasian ditto
Fig. 3 Intrusion zone cross section of Sunda Strait at Krakatau point:
The sub-layer separates into 2-segment layers by compression-shear while being pressed from Sumatra and Java sides. That is;

From a point 150-km before Krakatau to the Krakatau, a compression-shear crack occurs in mid strait. It’s triangle’s E side shown with a dark green line in Fig. 1. It develops across the full diagonal cross-section of the sub-layer. cf. Fig. 4 (a). It gives a solution to the intra-sub-layer conflict. After separation, the Java-side sub-layer creeps in beneath the Sumatra-side one. Krakatau is near the N-vertex in the triangle. Both the separated segment-layers have been free from the mutual constraint.

As the mechanism of the separation of the sub-layer plays a key role in the Krakatau eruptions, it’s elaborated in the next Sub-sect.

Mechanism of Krakatau Eruptions

General
The Krakatau eruptions are, in principle, steam explosions. While moving, hot magma may meet water. Then, it generates steam. But it isn’t explosive. To make steam explode, explosive energy must be stored in forms of compression and heat. Then, when it’s released, steam explodes. Therefore, if this process is properly explained, it’s the mechanism of eruptions (of tsunamis as well). As it has yet to be given, fantastic hypotheses are abundant. In this Sub-sect. he forwards the mechanism before readers.

Sub-layer’s separation to 2-segment layers
Fig. 4 (a) shows the separating the sub-layer to 2-segment layers. Fig. 4 (b) is an upper view of Fig. 4 (a). This triangle corresponds to the green triangle in Fig. 1 & Fig. 1 in his past paper [5]. This triangular area is the stage where the molten magma is generated. The next Sub-sub-sect.       
 (a)    Perspective

 (b) Plan
                                                           
(c) Side View
Legend: a: Sumatra-side’s sub-layer, b: Java-side’s sub-layer, c: Java-side’s separating sub-layer, d: Separated segment layer, e: Both-sides’ conflicting part
Fig. 4 Model to explain separation of 1/3 depth sub-layer of lithosphere
His past paper [5] explains the separation as follows:
 ___   ___   ___   ___   ___   ___   ___   ___   ___   ___   ___   ___   ___   ___   ___   ___   ___   ___   ___   ___   ___   ___   ___   ___  
“After collision, they [Comment: Sumatra and Java plates of lithosphere] advance north into the Sunda Straits, one-above-another, rubbing against each other in a wedge-like triangular zone, in which Krakatau is in mid-edges. Every destructive geophysical phenomenon in the Strait, such as volcano, earthquake, fault and tsunami, emerges from this death-triangle. For example, unlike Java and Sumatra Is., shallow earthquakes happen up to the location near from Java Sea. The Krakatau represents the phenomena in the death triangle with its significant status in geophysics and a historical display in 1883. cf. Fig. 1.”
    

% ! ∆:  Epicenters of shallow earthquakes in a triangle zone (1970~1980),
Red circle: Krakatau Volcano-Seismic Complex, -----: Sunda Strait Bridge (SSB) route
Fig. 1 Shallow earthquakes occurring in the Sunda Strait volcano-seismic death triangle
     Source: Institute of Industrial Development (1987) / Quoted by [].
  ___   ___   ___   ___   ___   ___   ___   ___   ___   ___   ___   ___   ___   ___   ___   ___   __
After separation, the lower (Java)-side segment layer has no more pressure from the Sumatra side. It advances frontally. The upper (Sumatra)-side segment layer has no more reaction from the Java side. It advances N30ºE. The friction between the 2-segment layers is minor. They move together N-ward at 7-cm/yr speed with no significant event.
Under this condition, the Sunda Strait plate has been in a dynamic equilibrium like a pendulum under steady-state vibration, while the W-Java and E-Sumatra areas adjacent to Sunda Strait is in a static equilibrium as proven by no active volcano but a few dead ones with remnant hot springs. It’s been so since 0-million-yr ago in a geological history timescale (7000-yr ago in a Krakatau human history timescale) in Sunda Strait’s 2-million-yr geological history timescale.

Process to critical Stage
1st Stage: Heat energy is generated in the triangular section by works of shear, compression, friction and defacement. Heat generation is strongest at triangle’s N-vertex because of stress concentration. It melts lithosphere materials. The molten magma rises up to the top surface of the ocean crust where it meets the tephra-sediment layer saturated with seawater. The molten magma can’t rise up in the tephra-sediment layer, because its unit weight is heavier than the tephra-sediment’s. It starts making a magma chamber dome of intrusive igneous rock with the tephra-sediment materials there. cf. Fig. 5. (a).
2nd Stage: New incoming magma entraps / entrains seawater there in a form of steam bubbles, circulates in the chamber, releases entrapped bubbles, which form a steam-foam layer at the dome crown and inflates the chamber. A part of magma stays under the foam-layer, the other adds a dome ring at its perimeter edge. cf. Fig. 5. (b).
3rd Stage: the mechanical equilibrium of 2nd stage has a limitation, because: (i) The quantity of incoming magma and steam is constant. (ii) The length of dome perimeter increases as the chamber swells. (iii) Hence, the performance of adding dome’s edge becomes irregular. (iv) It results in the leakage of magma at any highest point around the dome’s perimeter. (v) Leaking magma has been saturated by entrained steam bubbles in a colloidal phase. Hence, its unit-weight has been lighter than the tephra sediment. (vi) It rises making a conduit up to the seabed where it emits and produces an edifice with steam-magmatic eruptions. The edifice counterweighs the chamber inflation. (vii) Steam bubbles can’t reach the s.w.l. until the summit vent nears the s.w.l. In the Event (2018), it was realized in1927. (viii) It took further 1 (yr) until the edifice was stable above the s.w.l. It was in 1928. In the Event (1883), it’s unknown when it’d emerged. It may have been 40~50 yrs after 416 AD.
Restoring equilibrium in this way, both the Events enter the 4th stage. cf. Fig. 5 (c).

                   (a) 1st stage


 b) 2nd stage






                                                                         (c) 3rd stage
Legend: a: Seawater, b: Tephra layer, c: Dome, d: Magma, e: Edifice, f: Steam-foam layer
Fig. 5 Development of Krakatau from 1st ~ 3rd stage                                 
4th stage: In this stage, incoming magma continuously brings steam as entrapped and entrained steam bubbles, outgoes leaving entrapped bubbles to the steam-foam layer, resulting in chamber inflation. An increase of edifice’s weight by the accumulation of extrusive igneous rocks on the edifice counters the chamber inflation. cf. Fig. 5 (c). The system is in balance until the steam-foam layer’s lowest EL comes down to the exit conduit’s lowest EL.
5th stage: When the lowest steam-foam layer’s EL becomes lower than the exit conduit’s lowest EL, the aspect in the conduit drastically changes from the magma dominant to the steam dominant formation. cf. Fig. 6 (a) & (b).

(a) Magma dominant formation in the 4th stage     (b) Steam dominant formation in the 5th stage
      Legend: a: water & other debris entered from outside, b: Steam, c: Magma, d: Plug
Fig 6 Formation in conduit
The conduit tends to be plugged by remnant magma of previous eruptions. In case of (a), plug’s strength is the same as extrusive igneous rocks. Its resistance against the uplift force from compressed steam in the steam pocket is weak. In case (b), plug is formed in the deeper EL in the conduit. Its strength is the same as intrusive igneous rocks, hence, is stronger than the one of case (a). The steam-gas in the under-plug pocket is from magma, which’s saturated by steam bubbles. Frictional resistance between the conduit wall and the magma is mitigated by the steam bubbles’ ball-bearing effect. Magma is pushed up by the magma in the chamber (case (a)), and by the steam in the chamber (case (b)).
The eruption is initiated by the collapse of the plug (both cases). In the case of (a), the feature of the eruption is characterized by an initial relatively small steam-ash explosive eruption followed by a magmatic eruption. In case (b), the initial steam explosion is the same but followed by a steam-magmatic explosion. Case-(b)’s eruption is stronger than case-(a)’s.
The above stated eruption pattern is for the eruptions in the conduits in the crater. The pattern of eruptions outside the crater, it may happen, is different from the above. Its eruption isn’t followed by (steam) magnetic eruption due to greater friction.
Morphological differences in the visual feature of edifice brought by the conduit status (a) and (b) are: first of all, a gradual edifice-EL increase, (case (a)), and remarkable sinking and gradual recovery of edifice, (case (b)). The cause of the former is the inflation of the chamber by steam bubbles brought by incoming magma and left there by outgoing one, and accumulation of emitted magma on the edifice. The cause of the latter is the quick discharge of steam from the chamber and gradual recharge of steam to it.
The 5th stage of Event (2018) started in Aug. 2018, and lasted until Event (2018). In Event (1883), it’d been from May 1883 to 26 Aug.1883. From the ends of these time points, the two Events enter different critical stages as follows:
Critical Stage: Event (2018)
The status change in the conduit brought about two visual features, viz. (i) sinking of the edifice and (ii) intensified eruptions.
At the time of Eruption (2018), the vents (2 in- and 2 out-side crater) had been as low as the s.w.l. They’d been filled with seawater and rainwater. The sectional area of the crater was 2*4 (km2) and of the four vents’ average cross sectional area was 0.52 (km2). The depth of water in the crater is about 0.003 (km). Ditto of the conduits is unknown. The conduits’ length was 0.3 ~ 0.8 (km). It was plugged at depth near from their lowest EL as steam explosions happen there, and after explosions, remnant magma free falls in conduits. cf. Fig. 6 (b). Suppose, conservatively, it was 0.3 (km) on average. Then, the stored water was 0.38 (km3). As of 21:00 local time (L), Dec. 22 2018, the conditions were set up and waiting steam explosions at the low ELs in the conduits.
Fig. 7 is a conceptual chamber-edifice-crater-vent formation at the critical stage of Krakatau Eruption (2018). As shown in Fig. 7, the magma chamber spreads unevenly to the SW side of the edifice. Hence, the ascent / dissent of the edifice are also unevenly prominent in the SW area of the edifice. The vents of outside & inside the crater rim had appeared on the then perimeter edge of the chamber at the respective times. Hence, some of them are inside the scope of the chamber at the critical stage of Krakatau (2018).
:vent
                                      Legend: a: Magma chamber, b: Edifice, c: Crater
Fig. 7 Conceptual layout of elements of Krakatau (2018)
Final stage: Eruption and Tsunami (2018)
The steam explosion had timely come. The water in the 4 vents and the crater was pushed out one by one within 3 ~ 4 (min) interval. It caused the Sunda Strait tsunamis (2018). cf. Photo 1.


 
                        
                  (a) Before Eruption                 (b) Just before Eruption            (c) after eruption
Photo 1 Status change of Anak Krakatau by Eruption (2018), Origin: JAXA’S ALOS-2 satellite
Photo 1 (b) was taken at about 05:30 L. It’s jugged so as sunrise at Krakatau is between 05:58 & 06:03 L and sun shines 110-m high E-side crater rim. The date is not 22 but 23 if UTC is converted to L.
It shows that the WL in vents and crater was as low as the s.w.l. at the time 8.5 hrs after the 21:03 L Eruption.  Photo 1 (c) was taken on 24 Dec. It shows there were eruptions (not a landslide) after the time when Photo 1 (b) was taken. There can be seen insignificant topographic changes after the eruptions. The island is covered by tephra in both sides of the NW-SE aligned crater rim which divides the island evenly. The SW-side crater is covered by tephra relatively thin to the NE-side slope due to the wind direction at that time. Despite the coverage, seawater is seen in the crater.
Ascents & descents vs. time are commonly occurred throughout Event (2018). It’s mainly by the magma chamber inflation and deflation, and partially tephra accumulation and erosion on the edifice. Photo 2 is before and after the time duration of Photo 1. These Photos explain it.
                    
               (a) before Dec. 19 2018                   (b) after Dec. 24 2018
Photo 2 Satellite images of before and after time duration of Photo 1
A SE-vent outside the crater at the s.w.l. initiated eruptions. It pushed out a conduit full of seawater. It’s the origin of the 1st tsunami wave. It was followed by an eruption of a NW-vent outside crater. It also pushed out seawater in its conduit. It caused the 2nd tsunami wave. Being stimulated by these herald eruptions, eruptions inside the crater were induced. It emitted the greatest quantity of sea-rainwater and caused the largest 3rd tsunami wave. The time of this eruption is not the one which gave the biggest amplitude in a seismic recorder at 9:03 pm L. After these 3, there can be seen 9 more consecutive waves. But they were faint tsunamis. They’re the tails of transient vibration by 3-waves’ incitation in a tide-gage cylinder. There might be real waves, but are reflected waves of the three. Further, the astronomical wave had been already in the full-moon Low Water Level (LWL), which’s lower than the crescent LWL, when these waves arrived at the Banten tide gauge. Hence, it doesn’t make sense to take them into account.
Critical Stage: Krakatau (1883)
Fig. 8 shows a conceptual chamber-edifice-crater-vent formation of Krakatau (1883) at the critical stage. The northernmost vent (Perbuwatan) is the 1st vent. The middle one (Danan) is the 2nd vent (1st relief vent). The southern one (Rakata) is the 3rd vent (2nd relief vent). Each had been born at each cotemporary chamber edge. But since then, despite the SW-expansion of the chamber, no more relief conduits had emerged. There was a hot spring at the E-coast near from the 2nd vent. cf. Fig. 8. But it’d failed to have become a relief conduit. In addition, the 3rd vent didn’t work as a relief conduit because its long conduit had been plugged.
Fig. 8 Conceptual layout of elements of Krakatau (1883), Legend: ditto Fig.7.
Final Stage: Eruption and Tsunami (1883)
Given the conditions as the above, there was a 200-yr dormant time. During this period, the steam-foam layer stored explosive power in a form of heat and pressure. When it overpowered the resistance of plug and friction in the 1st and 2nd conduits, steam-ash, steam-magmatic explosions started, having made high columns in the sky. It might have been in May 1883. Up to this time point, the phenomena are qualitatively the same as Krakatau (2018) though quantitatively much greater. After this, the phenomena of Eruption (1883) went on in a qualitatively different way from the Eruption (2018).
On Aug. 26 1883, some steam explosions at low-ELs in conduits marred the nearby chamber dome. On Aug. 27 1883, Magma and steam-foam at the marred dome around the conduit were exposed to the seawater-rich tephra-sediment layer outside the chamber. It resulted in steam explosions. They’re local failures. Their biggest effect was to have blown away the parts of the edifice. It directly means the removal of counter-weight. It happened 3 times. Each caused each tsunami. The last 4th one, the biggest, happened having involved the dome crown. It was a total failure of the dome, and a full-capacity steam explosion. It’s the Krakatau Eruption (1883) in a narrow sense. It’s been a record holder in many geological, geophysical, metrological items up until today.
In the case of Eruption (2018) the steam explosion is constrained in a conduit, hence, its effect was 1-D (vertical) in terms of explosive force. One of the horizontal consequences, the tsunami, was also caused by the vertical component of the steam explosion at the deep ELs in conduits. But in the case of Eruption (1883), the force, whose focal center was 400-m deep, was not constrained in conduits. It was 3-D explosion of a chamber. Hence, its effect was also of 3-D. The horizontal component pushed aside soil and seawater. It caused tsunamis.

Provable Interval of Eruptions
The primary factor that governs the interval is the time when the steam-foam layer’s lowest EL descends down to the conduit’s lowest EL. It results in greater steam explosions than they’ve been. In the Event (2018), it activated at least 2 conduits outside the Anak Krakatau’s crater rim (one in the SE and the other in the NW of the rim). They mitigated the excess pressure, deflated the chamber and lowered all the vents’ ELs. In effect, it caused the Sunda Strait tsunami (2018). After Eruptions (2018), Krakatau has gone back to the stage 2 and now on the way of the 2nd trial for Krakatau (1883). Then, does the next Krakatau (2018) will happen (2018 – 1883) – (1928 – 1883) = 90 (yrs) after 2018? No. The 2nd trial will reach a higher summit, hence; take a longer time than it. Its crater won’t necessarily descend down to the s.w.l.; hence, it won’t be followed by tsunamis. Reasons are: 1st: ‘The chamber-conduit system of Krakatau was not broken by Krakatau (2018). It was deformed under high temperature and pressure.2nd: ‘Any structure made of non-organic materials generally increases its strength by deformation under high temperature and pressure.’ That is, ‘the chamber-conduit system of 2nd trial is stronger than of Krakatau (2018).’
The post-Krakatau (2018) development depends on if a new relief conduit would be made timely at a contemporary dome edge. It plays a role of a relief valve. The chamber grows by adding a ring at its perimeter. The chamber must make new relief conduits along the contemporary perimeter whenever needed. If the system has a relief conduit, it can ease itself by releasing the excess magma and steam, even if the 1st conduit happen to be plugged.
After a few Krakatau (2018) type trials for the next Krakatau (1883), the edifice will reach 800-m EL. Under this condition, magma around the dome edge becomes too consistent to leak. That is, there’s no more new exit conduit. If working conduits are plugged, the volcano seems to be dormant, though potential energy for future explosions is being stored in this period. It may last a couple of hundreds of yrs. Thus, the next Krakatau (2018) will come before 2400, and the next Krakatau (1883) will have been ready to happen before 3500.
The eruptions of Krakatau (1883) scale have happened at least 5 times. They had happened after Sunda Strait was in a dynamic equilibrium, i.e. it’d completed its formation. As the eruption is periodical, the time when Sunda Strait had been completed is computed 5*1400=7000 (yrs) ago.

Deduction by Lab Test

General
The induction study has been done. But it’s still in a status of a Hypothesis. It must be backed up deductively. If not, it’s as illusory as the underwater landslide hypothesis. Before entering discussions, there’s something to be confirmed in advance, i.e.:
(1) The Krakatau eruptions are in principle steam explosions.
(2) To make steam be explosive, it must be compressed. To compress steam, there must be a vessel. For the vessel, there’s nothing other than the magma chamber. But the chamber’s dome is neither waterproof nor steam-tight. It can be waterproof & steam-tight, only if water is in a steam-bubble phase.
(3) Steam bubbles play not only a role stated above but also a leadoff role throughout all the process in eruptions as a catalyst.
In this context, to prove the functions of steam bubbles is a leadoff proof of the Hypothesis. It’s been done by lab tests. As it’s impossible to realize the real conditions of 1300 (ºC) and 2000 (t/m2), the tests have been done under 100 (ºC) and normal pressure. However, so far as they’re kept constant in a test, the temperature and pressure won't affect their qualitative behavior. It’s to be noted that the qualitative behavior of steam bubbles or generally all kinds of bubbles of steam, air, gas etc are the same, regardless of its film materials, i.e., solvent of water, alcohol or molten magma. Hence, any behavior of steam bubbles & foam in a model chamber-conduit system is analogous to the steam bubbles & foam behaviors in a real chamber-conduit system of Krakatau.

Lab Test
The testing feature is shown in Photo 3. The principle of the test is shown in Fig. 10. The behavior of the steam bubbles is observed in the test as follows:
Switch on the gas stove, and the test starts. Before detergent sol (sol) boils, the table cloth placed in mid mold height is relaxing. When it boils, steam bubbles start rising. The bubbles can’t pass through the table cloth. The cloth stores bubbles by inflating itself. The steam bubbles make a steam-foam layer at the dome crown. The sol in the chamber keeps its position under the steam foam layer. As the sol in the chamber has been saturated with entrained steam bubbles in a colloidal phase, it’s also uneasy to pass through the table cloth and forced to leak from the dome’s perimeter edge. If a pipe is set as shown in Fig. 10, the leakage occurs through this pipe. The surface EL of the sol in the pipe is higher than the one of the sol on the chamber as the sol’s density in the pipe is lighter than the one above the dome because of (i) the former is hotter than the latter and (ii) the former is saturated by entrained steam bubbles at about 15 % but the latter isn’t. When the lowest EL of the steam-foam layer comes down to the pipe’s lowest EL, steam starts leaking from the pipe. In this case, steam foam pushes up sol in the pipe by its buoyancy resulting in a quick emission of sol. It should be recalled that the leakage of sol or steam foam never occurs from a dome crown without the pipe.
                                      

Legend: a: safety net, b: detergent sol surface level, c: table cloth, t: boiler

d: steam- bubble-saturated sol surface level, e: circulation of steam-bubble-saturated sol,

f: steam-bubble-saturate sol, g: fire, h: gas stove, i: gas hose, j: steam-foam layer,

k: emission of steam-bubble-saturated sol, l: pipe, m: steam-foam, n: gas cylinder, p: entrapped steam bubble

Fig. 10 System to test steam-foam-effects          Photo 3 Test to probe steam-foam effects
Every aspect in the test is one-by-one corresponds to every Krakatau eruption’s aspect. Readers can confirm it by comparative readings of this Sub-sect. and the explanations of Fig. 5 & 6.
The lab tests had been done in the frame of the steam-foam dishwasher development studies. The results have been already presented [19].

ONGOING STUDIES

General
The main stream studies’ direction is, ‘The Sunda Strait tsunami was caused by an underwater landslide.’ Hence, this study shall focus on the 2 basic factors of it, i.e., the entity of the tsunami and reality of the underwater landslide.

Entity of Sunda Strait Tsunami

Data
As for the tsunami arrival time, there’re various statements. According to mass media, they’re:  (i) 21:27 L 14:27 UTC, (ii) 21:30 L 14:30 UTC, (iii) between 9:27 p.m. and 9:53 p.m. L, and (iv) around 21:38 L 14:38 UTC, etc.
As for tsunami height, there’re also a variety of reports, e.g., (i) 90 cm in Serang and 30 cm in Lampung on top of 2-m high tide, (ii) at least 2 m, (iii) more than 5 m, (iv) 13 m, (v) nearly 10 feet high etc.
As to the departure time of a tsunami from Krakatau, there seemed to be no other statement other than 21:03 L 14:03 (UTC). It is the time when a seismographic recorder was broken by the biggest tremor.

Verification by this Paper
In a study on a wave motion, there’re 3 essential elements, viz. wave’s height, period and length. If these have been known, other elements such as wave velocity, dissipation constant, phase difference etc can be computed from them. The necessary data to know the 3 fundamental elements, excepting the departure time of a wave, are all in Fig. 12. Besides Fig. 12, there may be other data sources. Though it’s unknown by what means they are obtained the data, Global Positioning System (GPS), computer simulation and site observation are the most probable ones. GPS’ errors are big especially in height. Computer simulation used to be lack in some indispensable input(s). Site survey is difficult to find data at the coast line. The data from tidal gage is, in every sense, most reliable if appropriately interpreted. He used only Banten’s data, since data are more smartly recorded than Panjan port’s ones. There’re 12 somehow-meaningful waves recoded in the 1st 2-hr duration. Among them, worthy to study are the 1st 3. The 1st wave was caused by the eruption at the SE-outside-crater vent. Its volcanic activity is in photos. The eyewitness’ testimony on the wave caused by the eruption is plausible. But the eruption at the W-outside-crater vent of the s.w.l. is obscure (there’s no vent corresponding to it). The vent that took part in the event is to be the NW-outside-crater vent. It’s been explained earlier how to read the tidal-gauge data. He reiterates the points of them.
(1) Wave height is generally measured from wave’s trough to crest.
(2) When the 1st tsunami wave reached the gauge, the astronomical tide had been already at the m.s.w.l.; hence, to composite the tsunami wave on the top of astronomical High Water Level (HWL) doesn’t make sense.
(3) The gauge is for the measurement of astronomical waves (period: 12 or 24 hrs). Hence, for the sake of convenience, it’s so designed as to over-damp metrological waves (period: sec. order). Tsunami waves (period: min. order) aren’t over-damped but under-damped. That is, the nominal wave height in the data sheet must be revised before usage*.
* 3 hints in revision: (i) Sunda Strait tsunami had only 3 waves. After them, the vents never regained the conditions to have mobilized more tsunami wave. The waves after the 1st 3 tsunami waves in the data sheet are dummy waves. They're the tail of the free vibration in a gauge cylinder. (ii) There may be reflected waves of the tsunami. It can be identified by its phase difference from the original waves. (iii) The calculation shall start with a logarithmic decrement.
The results are shown in Table 1.
Table 1 Essential elements of 1st 3 waves (based on Fig. 11 (a))
Item
Unit
1st wave
2nd wave
3rd wave
Wave height
M
3.1
2.0
7.0
Ditto length
Km
       10.8
      11.3
7.8
Ditto period
min.
9.1
9.5
6.6
Ditto velocity
km/min.
  1.19
  1.19
  1.19
Arrival time  date
hr:min:sec. L day  month  yr.
21:47:36 L
22 Dec. 2018
21:56:42 L
22 Dec. 2018
22:06:12 L
22 Dec. 2018

                                                                      

      (a) Composite of astronomical tide &                             (b) Locations of tidal gauge stations

         Sunda Strait tsunami (Banten)
Fig. 11 Sunda Strait tsunami wave recorded by astronomical tidal gauge
In Table 1, the numbers typed in bold have random errors of 30 (sec.) in time and 20 (cm) in height. The authorized arrival time (21:27 L) is incompatible with Fig. 11 (a), so with Table 1.
The italicized numbers have a constant error, because the calculations are done based on a departure time (21:03 L) that’s a sole authorized data. Though a true departure time is sooner than it, he can’t define how soon. Hence, for the time being, he follows the authorized one. If it’s several min. sooner, all the italicized numbers are uniformly reduced by about 10 (%).

Reality of Underwater Landslide

General Recognition
Coordinating Maritime Affairs Minister Luhut Pandjaitan said, ‘The experts have determined that the Sunda Strait tsunami was caused by Anak Krakatau's increasing volcanic activity that had triggered an underwater landslide. Experts from the BMKG, the Agency for the Assessment and Application of Technology (BPPT) and the Energy and Mineral Resources Ministry will be working on a team to perform marine geological and bathymetric surveys in the area surrounding Anak Krakatau. The team is to start work as soon as conditions are favorable.
Studies must be going on with this general recognition.

Development of ongoing Studies
There has been no information of site investigations up until now. The investigators may have learnt that the seabed topography left no evidence of the alleged underwater landslide due to the consecutive seabed deformation since then. Under the situation as this, if the site investigations have proved the said underwater landslide, it’s wonderful per se. He shall learn if its logic is of ‘A bucket shop profits when wind blows’ a Japanese proverb that symbolizes a forced analogy.  However, as explained earlier, it doesn’t matter for the ongoing studies even if it can’t be confirmed. The matter is, ‘It won’t be denied.’ Hence, the set up hypothesis isn’t abandoned. Fig. 12 concretely explains the unchanged doctri1ne. It explains the event’s sequence as follows:
1st: An underwater layer (green in Fig 12) slid on 22 Dec. 2018, maybe at 21:03 L. As its top surface is at the s.w.l., it’s visible in left-upper Photo taken on Dec. 23.
2nd: The SW-side flap of edifice collapsed by eruption on 24 Dec. as shown in right-low Figure. That is, it’s no relation to the underwater landslide.
The above 2 chronicle expressions extracted from Fig. 12 have 2 contradictions. They’re as follows:
(1) It assumes a big SW-ward eruption that involves the main conduit. This eruption   is incompatible with the 21:03 L eruption which was so big that the seismic gauge was broken. One must be chosen.
If the former (or latter) is chosen, the hypothesis (or right-upper Photo) loses its ground.
(2) The right-upper Photo shows the scope of 64 hectares of lost land by red real / dotted lines. Look it at carefully and readers can see almost 2/3 of land is still remaining after the tsunami. It means that a 20-hectare landslide caused the tsunami. Meanwhile, officials stated that approximately 64 hectares of the volcano had collapsed into the ocean. The collapse made the height of the volcano be reduced from 338 to 110 (m). cf. Fig. 15. It must be elaborated.



Fig. 12 Landslide explained by ongoing studies

Denial of underwater Landslide

General
In this Sub-sect., he denies the underwater landslide hypothesis. As explained in previous SECT. the site investigations can neither confirm nor deny the underwater landslide. He denies it by a different means.
How does underwater landslide happen?
1st: A landslide used to happen in a slope of between 30º and 45º. A slope less than 30º is too stable to slide. A slope more than 45º is too strong to slide (Rakata’s 90º cliff is 150 yrs stable). Hence, the site must be dominated with the slopes of 30º~45º. Among them, slopes of less than 30º are eligible to be the site. One of them caused a tsunami wave. Good luck for searches.
2nd: A slope being at an angle of repose slides when the weight of the soil of the slope increases. It’s realized by rain on the ground. But underwater soil has been already saturated by water. Hence, it’s not the case at all.
3rd: A landslide can happen when soil’s frictional resistance decreases. It happens at a seismic time by liquefaction of loosely compacted sandy soil. By nature, the liquefaction doesn’t occur twice at the same place. Krakatau had experienced a series of stronger volcanic quakes than the ones of Dec. 22 since June 2018 up to the date. The seabed around Krakatau had been already immune to the volcanic activity of the Dec. 22 eruption.
In any respect, the underwater landslide hypothesis hardly comes from the above criteria. The worldly studies are supported by a wrong premise that assumes, ‘There’s no solution to solve the Sunda Strait tsunami besides the underwater landslides.’ But as witnessed, 1st and 2nd waves were generated by eruption itself with no underwater landslide.

How does underwater landslide cause tsunami?
Suppose here’s a water channel of equal section. Water flows in it at equal flow velocity (V) and a constant water level (WL). If there is a projection on the channel’s bed as seen in Fig. 13, it gives effect on WL. If water doesn’t flow, i.e., V=0, but the projection moves at V, the effect is the same. It might cause a tsunami. The matter is: What’s the tsunami waves’ aspect?


                     Fig. 13 Effect of projection at channel bed on surface of flowing water
Fig. 12 assumes an underwater landslide to happen at the depth of much deeper than the critical water depth (hc). So it’s the case of a Steady flow to which the Bernoulli’s law is applicable. As water on the projection flows faster than the upper- and lower-side of the projection, the velocity head is higher. As the potential head is constant throughout the waterway, the pressure-head is lower on the projection. That is, WL on the projection becomes lower than the upper- and lower-side WL. cf. Fig. 13. Hence, the tsunami must arrive at coasts with an undertow. However, every wave of the Sunda Strait tsunami is initiated with a press wave. Therefore, as far as data & theory are so given; the tsunami waves were not caused by the underwater landslide. He is looking forward the site-survey data that’d hardly justify the alleged cause.
There’s a minor opinion that says, ‘An on-ground landslide caused a tsunami.’ cf. Fig 14. But it isn’t the case. There’re 3 pieces of evidence, viz. (i) There’re many satellite images of Krakatau before and after the tsunami. But no image shows any trace of landslide proposed by Fig. 14. If it happened, there must be seen the debris covering the lower side of the landslide site. There can be seen nothing of such. The lower-side surface after the event is the volcano’s crater itself. (ii) After the slide, the conduits in the edifice must remain in positions like towers, as their strength is stronger than other volcanic materials of the edifice. There’re many photos to prove it. (iii) The remnant of Krakatau (present Rakata) Island’s N-cliff was a result of an ultra-great volcanic shock. But it didn’t landslide. It has kept its almost vertical status for 136 yrs since then. It proves Krakatau edifice material’s stability for landslide. Anak Krakatau is built with the same material as Krakatau’s one as both are made of tephra from the same source. 
That is, the cause of the disappearance of the edifice was not by a landslide but sinking. The EL of the summit vent dropped by 228 (m). Fig. 15 is a real profile of Anak Krakatau before and after the Dec. 22 eruption. Put landslide profile(s) in it. He can’t do it. Can you?

Fig. 14 Concept of on-ground landslide


Original Figure & Photo: seen in each Fig.
Fig. 15 Krakatau before & after 22 Dec

PREVENT KRAKATAU FROM ERUPTIING BY STEAM POWER APPROPRIATION

In the above SECTs, the mechanism of Krakatau has been explained. Based on it, counter-measures, such as prediction of / preparation for Krakatau eruption, can be done. In this SECT., making a step forward, the method of prevention of Krakatau eruption by utilizing Krakatau eruption energy is suggested.
There’s been already geothermal power generation. The destruction of environment is the matter in this conventional system. Iceland struck a pocket of magma at 2.1-km deep in 2009. A new type of geothermal power generation started having used the high temperature & pressure of the magma steam. It was the world’s first magma-enhanced geothermal system. Really, Iceland is located on the magma upwelling point; hence, it’s possible to reach magma. Nonetheless, this was only the third time in recorded history that magma had been reached. Further, all the reached aren’t necessary good enough for the purpose, because the magmatic steam is limited in quantity.
On the other hand, in the case of Krakatau steam power generation, steam is stored in a magma chamber (Natural tank). Its location is known. Its highest EL (dome crown) is 300-m deep from the s.w.l. Though not yet estimated, steam reserves are great and supply is stable. It needs none of mining, refining, storing, transport, disposal & abrogation installation. From any points of view, Krakatau Steam Power generation is more bankable than any kinds of power generation. It is public-nuisance free, and even prevents volcanic hazard from occurring. It needs no special technique besides high-temperature durable pipe which had been already developed in Iceland.

CONCLUSIONS AND RECOMMENDATIONS

This paper summarizes its conclusions as follows:
(1) Krakatau (2018) is its 1st trial to the 2nd Krakatau (1883). The two (had) happened in the same complex of the same particular volcano-geologic settings. Hence, they (had) had qualitatively the same cause, steam explosions. Only a difference is, if the explosions (had) involved the steam-magma chamber. All the quantitative differences between them come from this point.
 (2) Hence, to identify the particular settings is a compulsory approach to the gate of Krakatau (2018) studies. The particularities are, ‘Shallow volcano-seismic activities in the Sunda Strait.’ Then, to induce volcano-geological mechanism of the particularities is the key to solve the Krakatau (2018). The fact identification has been done to some extent. But the inductions from the facts are still in a trial and error status.
(3) The greatest factual error of the secular studies is to regard the oblique Sumatra as a given fact. And the effects of Australian plate are the consequences. Really, Sumatra is pushed toward N30ºE perpendicularly to the Sumatra fault line of W30ºN. Sumatra rotates anti-clockwise by this force’s E-ward component. S-side half of Sumatra of the Sumatra fault doesn’t move W30ºN relative to N-half of Sumatra. In fact, N-half of Sumatra is dextrally strike slipping relative to the S-half which can’t move to E due to reaction from Java side plate. But N-half can, because no constraint from the Java plate as explained. Many of wrong concepts in studies have their origin in this point.
 (4) The clockwise rotation made a V cut between then adjacent Java and Sumatra somewhere on the current Sunda Strait’s southern entrance. This V cut has neither continental crust nor lithosphere. The Australian plate didn’t subduct but intruded straight into it. It worked as a wedge to open the present Sunda Strait. In this context, Sunda Strait is under a 3-D compression regime though there’re locally a few tension areas.
 (5) The depth of the Sunda Strait plate’s surface is 6-km deep from the seabed vs. 60-km in the case of subduction zone. Hence, there’s no ordinary tectonic activity. This is the very reason why the secular studies (being possessed by the plate tectonics) won’t take the shallow lithosphere into account. In fact, it’s the mother of all the shallow volcano-seismic activities. Hence, if its mechanism is set up, the respective problems such as Krakatau (2018), Sunda Strait tsunami as well, can be correctly solved.
 (6) The mechanism of the Sunda Strait plate’s behavior is, in short, its compromise with the adjacent Sumatra and Java plates on the imbalance caused by their respective ways of advance. It’s concretely explained in the following items from (7) to (13): cf. Fig. 1.
 (7) The Australian plate can’t enter the V-cut space with the plates of both sides, as the mantle under the lithosphere flows keeping the same level as it is. It doesn’t sink unless otherwise subjected to downward force. It is also pressed from both sides when it wedged itself into the V cut. So when it’s about to intrude into the V-cut of would-be Sunda Strait, there’re some works to do strain-stress-wise, which cause seismic activities.
 (8) The remarkable one in Item (7) is 3-chains of quakes in the E-side entrance of the strait. These are caused by tensile-bending stress due to pull-down force through the lithosphere that joins the strait-going Sunda Strait plate and subducting Java plate.
 (9) The same happens in strait’s W-side with a time lag. This time, the pull-down force is from the lithosphere that connects the Sunda Strait plate to the Sumatra plate. It happens later than the E-side ones due to W-side’s more moderate subduction dip angle and depth than the E-side’s. As it goes on under the 3-D compression regime, cracks can’t be deeper than 1.8 (km) [20]. Because of sectional reduction due to cracks, the connecting lithosphere is cut off at its highest EL. It develops N-ward up to the N-end of the strait. It’s proven by the fact that the cracks no more extend their length to the N, and no more area of cracks expands to E.
(10) Next is a main event, the slip-off separation of the 1/3 depth sub-layer to 2-segment layers by shear under the 3-D compression regime. The shear section is triangular and is in mid strait. The driving power is compression force from the wedge action at both sides of Sunda Strait plate. After the separation, The Java-side segment layer creeps in beneath the Sumatra–side one. They advance to each direction (frontally and N30ºE respectively) with minor friction, hence, no event

(11) After the separation, 2-segmet layers are free from the mutual constraint. At this time point the Sunda Strait had been reached dynamic equilibrium, i.e., it’s a steady-state motion toward N at 7 (cm/yr). It’s to be noticed that the triangular section and its super structures (conduits, magma-steam chamber and edifice) keep the constant position perpetually.
(12) The Krakatau eruption is a steam explosion. There’s a catalyst in its process, i.e., ‘steam bubbles’. Steam in a gas phase can’t be stored & compressed in a chamber because of leakage, so can’t explode in mass. Steam in a bubble phase can’t pass hair cracks because of bubble-films’ high viscosity and surface-tensile strength. Besides this function, the entrapped and entrained steam bubbles play an essential role in steam-explosion eruptions.
(13) The Sunda Strait tsunami (2018) was caused by emission of water in conduits. It was witnessed for the 1st and 2nd waves. The 3rd one can’t be an exception. An alleged underwater landslide can’t generate real tsunami waves. What is on earth, there wasn’t landslide.
Based on the conclusions, this paper summarizes its recommendations as follows:
(14) Any protective countermeasures for Krakatau can be set up as per the above conclusions. This paper, more aggressively, recommends preventing the eruption itself by controlling the steam pressure in the chamber. Further, it suggests an appropriation of the steam power for energy. He strongly recommends starting with the estimation of Krakatau’s potential power.
(15) He recommends Krakatau event researchers to pay more attention to the particular settings (shallow volcanic activities). It’s the beginning point to approach the truce. If it’s been done, enter its mechanism. It’ll result in reviewing current studies.
(16) He recommends participants of Sunda Strait linkage project to realize the volcano-seismic dynamism in the Sunda Strait. If it’s been done, enter the review of current bridge & tunnel plans. If not, your deeds are tantamount to digging (erecting) your own grave (-stone) of 2-fold luxury of expense and experience.

EPLOGUE

He advises readers to learn his past papers, [11] ~ [19]. They’re studies on Airbus accidents under a computer programmed automatic control system. This system, now prevailing societies, has brought about 2 side-effects: (i) a mass-production of Acquired Basic Intelligence Deficiency Syndrome (ABIDS) sufferers (nerds) and (ii) societies’ lacking ability to solve accidents, as accidents happen beyond the programs and at a basic intelligence level, cf. [1] ~ [10]. Don’t be ashamed of ABIDS, as most of experts are nerds. But be ashamed of not getting rid of ABIDS, as AIBIDS is treatable. To learn his papers is the best remedy. This paper is a specific medicine. He gives it free of charge. cf. next paragraphs.
He forwards an idea of Krakatau volcanic steam power station before the societies concerned. It’s royalty-free. But the users are kindly advised to ask him knowhow for prospective problems on the way of practices. Some may don’t. It’s OK. But don’t attribute any failure to the inventor. It’s the same for the steam-foam dishwasher exhibited in this paper.

REFERENCES

 

[01] Sohei Matsuno, Zul Hendri, ‘A STUDY ON THE CAUSE OF KUKAR BRIDGE COLLAPSE,’ www.iba.ac.id, Jan. 6, 2012

[02] Sohei Matsuno, Zul Hendri, ‘’A STUDY ON THE CAUSE OF KUKAR BRIDGE

      COLLAPSE (sequel),’ www.iba.ac.id/

[03] Sohei Matsuno, UIBA'S AND HAPPY PONTIST'S KUKAR BRIDGE COLLAPSE THEORY,’ www.iba.ac.iddocuments/83
[04] Sohei Matsuno, ‘2011 JAPAN QUAKE OVERPOWERS PLATE TECTONICS’, repo.ia.ac.id/index
[05] Sohei Matsuno, ‘SUMATRA-JAVA LINKAGE PROJECT OF FEASIBILITY’,
[06] Sohei Matsuno, ‘CAUSE & PREVENTION OF COASTAL FLOOFING, JAKAETA FLOODING AS A CASE,’ www.iba.ac.id/
[07] Sohei Matsuno, ‘JAKARTA FLOOD PREVENTION PROJECT WITH A TRUE CAUSE,’ www.iba.ac.id/ 8 Mar 2013
[09] Sohei Matsuno, ‘JAKARTA-FLOOD PREVENTION BY TRAINING DIKE vs. GIANT SEA WALL,’ www.iba.ac.id/,

[10] Sohei MatsunoSEA LEVEL RISE AND COASTAL FLOODING (JAKARTA),

      www.iba.ac.id/

[11] Sohei Matsuno et al, ‘A CAUSAL STUDY ON THE AIRASIA AIRBUS CRASH EVENT,’ www.iba.ac.id/  2015

[12] Sohei Matsuno, Asmadi, ‘A STUDY ON LUFTHANSA GERMANWINGS AIRBUS  CRASH EVENT,’ www.iba.ac.id/documents/, 2015

[13] S. Matsuno, ‘STUDY ON LUFTHANSA GERMANWINGS AIRBUS CRASH,’

        www.iba.ac.id/
[14] Dr. Sohei Matsuno, MS. Pujiono, ‘LEARN BEA'S PRELIMINARY REPORT ON LUFTHANSA CRASH,’ www.iba.ac.id/documents/

[15] Sohei Matsuno, ‘STUDY ON RUSSIAN METROJET AIRBUS CRASH,

        soheimatsuno.blogspot.com/, Jan 8, 2016
[16] Sohei Matsuno, ‘REVIEW OF AIRBUS CRASH & BUDGET SYSTEM -- given new data by Daallo event & AirAsia –soheimatsuno.blogspot.com/, May 30 2016
[17] Sohei Matsuno, ‘STUDY ON EGYPTAIR AIRBUS CRASH,
[19] Sohei Matsuno, Kimora Matsuno, ‘STUDY ON AIRBUS CRASH BY ANALOGY TO DISHWASHER SLUMP,
         soheimatsuno.blogspot.com/2018/06/study-on-airbus-crash-by-analogy-to.html Jun 6, 2018
[20]SEISMICITY OF THE SUNDA STRAIT: EVIDENCE FOR CRUSTAL EXTENSION AND VOLCANOLOGICAL IMPLICATIONS,’ TECTONICS VOL. 10, NO. 1, PAGES 17-30, FEBRUARY 1991

1 comment:

  1. How are you prof matsuno, this your student that that have a lesson from you with design and calculating musi 3 bridge for our minithesis to obtain my degree in bachelor from tridinanti university.

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