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:
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“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 [].
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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).
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.
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.
(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. 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.
(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’,
www.akademika.iba.ac.id/, Aug. 1 2012
[06] Sohei Matsuno, ‘CAUSE & PREVENTION OF COASTAL FLOOFING, JAKAETA FLOODING AS A CASE,’ www.iba.ac.id/
[08] Sohei Matsuno, ‘JAKARTA FLOOD
PREVENTION WITH A TRUE CAUSE (sequel),’ www.lba.ac.id/, 30 Apr.2013
[10] Sohei Matsuno, ‘SEA
LEVEL RISE AND COASTAL FLOODING (JAKARTA),
[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,’
[18] Sohei Matsuno, Kimora Matsuno, ‘LEARN AIRBUS CRASH FROM METROJET-/EGYPTAIR-EVENT,’ soheimatsuno.blogspot.com/, Nov 29, 2018
[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