SSS24-01

Japan Geoscience Union Meeting 2016

Modification of the log-normal distribution model based on the small sample theory*Masami Okada1
1.Meteorological Research Institute
Introduction
Log-normal distribution model based on the small sample theory is a statistical sophisticated model
to calculate the probability of forthcoming repeating events on the renewal process. We
prospectively forecasted probabilities for small interplate repeating earthquakes along the Japan
Trench (Okada et al., 2012). The number of forecasts in four experiments from 2006 through 2010 was
528 of which 249 cases were filled with qualifying event. Total of probabilities of forecast was
212.9 which was surely less than 249 of observation and the probabilities was rejected by the
N-test. The bias of lower probability is confirmed by numerical simulation with random numbers,
too. Hence I tried to modify the LN-SST for better forecasting.
MethodSuppose n+1 random variables Xi=log(Ti) and Xf=log(Tf) obey a normal distribution N(μ,σ^2).
Xf=log(Tf) represents the interval from the last event to the forthcoming one. Take the variable,
as follows;
Z=sqrt((n-1/(n+1))*(Xf - Xmean)/S.
It is well known that the Z-variable follows a t- distribution with the n-1 degree of freedom. Here
Xmean and S are mean and standard deviation of n variable of Xi. At forecasting time we cancalculate the values of Xmean and S, then the expected distribution of Xf is calculated, too. The
probability of events in the forecast period is given with the conditional probability from the
distribution of Xf.
Possible reason of lower probability are as follows;(1) The t-distribution spreads wider than standard normal distribution and has a lower peak of the
distribution.
(2) The expression of the conditional probability is not linear, then the forecast probability may
tend to lower.
Modification
It is possible improvements for LN-SST to correct the bias of lower probability and to improveforecast score, as follows;(1) Keep a definition of Z mentioned above intact and increase the degree of freedom.
If we raise one degree of freedom for the data of the experiment, the total of forecast
probabilities increases to 217.0 from 212.9, and the results improve somewhat, too.
(2) Increase the probabilities with some quantity depending on calculated probability.
The original probability from 0 through 1 is converted with a formulae, y=log(p/(1-p)) into
infinite interval, then suitable value (e.g., c=0.3) is added on y. Revised value is given by
inverse conversion from y to probability. The total of forecast probabilities becomes 241.0, andthe results is considerably improved (figure 1).
Keywords: repeating earthquake, forecast of earthquake, log-normal distribution, small sample
theory©2016. Japan Geoscience Union. All Right Reserved.

- SSS24-01 -SSS24-01©2016. Japan Geoscience Union. All Right Reserved.

Japan Geoscience Union Meeting 2016

- SSS24-01 -SSS24-02

Japan Geoscience Union Meeting 2016

Statistical investigation of pre-seismic ionospheric disturbance from the in-situ plasma
observation of the DEMETER*Hidetoshi Nitta1, Shoho Togo1, Masashi Kamogawa1, Jean-Jacques Berthelier2, Tetsuya Kodama3,
Toshiyasu Nagao4
1.Department of Physics, Tokyo Gakugei University, 2.LATMOS, France, 3.Earth Observation Research,
4.Earthquake Prediction Research Center, Tokai University
We investigate ionospheric disturbance observed by the DEMETER plasma probes, which are ISL(Electron density and temperature) and IAP (Ion density and temperature). Since there are several
papers concerning the pre-seismic ionospheric disturbance by using the data of electron/ion
densities and temperature, we verify the reported pre-seismic anomalies by means of superposed
epoch analysis. From the whole data set of the DEMETER, the superposed epoch analysis showed thatthe plasma disturbance appeared near the epicenter around 40 hours before the earthquakes. On theother hand, in the case of randomly generated earthquake catalogue, no similar anomalies appeared.
Keywords: Earthquake, DEMETER, Ionosphere©2016. Japan Geoscience Union. All Right Reserved.

- SSS24-02 -SSS24-03

Japan Geoscience Union Meeting 2016

Earthquake occurrence rate after pre-seismic-like ionospheric disturbance appearance using
the DEMETER data
*Shoho Togo1, Hidetoshi Nitta1, Masashi Kamogawa1, Jean-Jacques Berthelier2, Tetsuya Kodama3,
Toshiyasu Nagao4
1.Department of Physics, Tokyo Gakugei University, 2.LATMOS, France, 3.Earth Observation Research,
4.Earthquake Prediction Research Center, Tokai University
We statistically investigate pre-seismic ionospheric disturbances by using the VLF electric fielddata of the DEMETER, following Nemec et al. (Geophys. Res. Lett., 2008; J. Geophys. Res.; 2009) andPisa et al. (J. Geophys. Res., 2013). Our replicated analysis also showed that the background
intensity of around 1.7 kHz electric field decreased within 4 hours before the mainshock withmagnitude of more than 4.8, using the complete data set of the DEMETER, i.e., 6.5-year.data (Figure1a). In order to understand the physical mechanism of the depression of the background intensity,
we selected 10 orbits highly related to the decrease of the intensity for the event analysis fromthe whole data. We applied statistical correlation to the whole data evaluating anomaly appearance
rate and earthquake occurrence rate.
Keywords: Earthquake, DEMETER , Ionosphere©2016. Japan Geoscience Union. All Right Reserved.

- SSS24-03 -SSS24-04

Japan Geoscience Union Meeting 2016

Evidence for the hypothesis of upwelling fluid from deep underground*Tameshige Tsukuda1
1.noneStress changes associated with crustal deformations may induce migration of fluid within the crust.
It is hypothetically expected that a volume of pore water or fluid, being suddenly pressured in
response to an elevated stress level in some seismogenic zone, will tend to intrude up into a crack
network, and incidentally emerge at the ground surface or in the aquifer near ground surface. Thathypothesis was presented in around 2005. The evidence at that time were as follows:
1) Frequent rises in well water temperature were observed at Iwakuni,Yamaguchi Prefecture,southwest Japan; 2) Gushing of groundwater at the sea bottom was considered to have occurred at the
Akashi Strait 2 days before the 1995 Kobe earthquake of M7.3, based on an interpretation of theappearance of brownish-black seawater found by the captain of a passenger boat; 3) Upwelling ofdeep hot groundwater was occurred at Inagawa Town, Hyogo Prefecture, southwest Japan, which was
associated with the 1995 Kobe earthquake. The well water temperature rose 3-4 ℃at the time of theshock, and decayed with a time constant of 1-2 years; 4) Heating of ground rocks by upwelling hot
water intruding into the fracture zone of an active fault, which is considered to be a precursor
for the April 1, 1995 Niigata-ken Hokubu earthquake of M5.5, was confirmed by a LANDSAT infrared
image in the northern Niigata area, central Japan, on a summer night in 1994. All of the abovetransient phenomena can be reasonably understood in the light of the hypothesis of pressured hot
water upwelling from deep underground in response to crustal movements around seismically active
regions.
The amount of the upwelling fluids will change according to the pressure changes due to deformationof the crust. Shallow groundwater temperature will also change according to the change of theamount of the intruded hot water from deep underground. It should be noted that the 2009 Suruga-bay
earthquake of M6.5 in Tokai area, central Japan, was accomapnied by precursory and after-effectchanges of groundwater temperature. That kind of changes were not detected by the strain meters
installed by JMA around the Tokai region. Precursory and after-effect temperature changes were
found for other earthquake events such as the 2011 Tohoku earthquake of M9.0.
Keywords: deformation of the crust, pore fluid deep underground, groundwater temperature,
precursory change©2016. Japan Geoscience Union. All Right Reserved.

- SSS24-04 -SSS24-05

Japan Geoscience Union Meeting 2016

Maximum Magnitude of Subduction-Zone Earthquake around Eastern Japan Estimated by Seismic
Moment Conservation Principle: Part 2*Fuyuki Hirose1, Kenji Maeda1, Yasuhiro Yoshida2
1.Seismology and Tsunami Research Department, Meteorological Research Institute, 2.MeteorologicalCollege, Japan Meteorological Agency
Kagan & Jackson [2013, BSSA] estimated maximum magnitude of events which will occur along
subduction zone in the world based on the seismic moment conservation principle by applying that tobackground seismicity from 1977 to 2010. The key point of this method is to replace total seismic
moment rate with the tectonic moment rate MT. Note that because the plate coupling rate χamong
components of MT has large uncertainty, the maximum magnitude obtained is dependent on χ. To avoid
confusion, the magnitude and the seismic moment are represented by “m” and “M”, respectively.They
modeled a seismic-moment-frequency-distribution by the truncated G-R law, tapered G-R law and Gamma
distribution. These laws have two parameters: β(=b/1.5) and Mc (is characteristic seismic moment
which represents the maximum magnitude. Corresponding magnitude is mc). Truncated G-R law do nothave events larger than mc. Whereas tapered G-R law and Gamma distribution allow occurrence of
events larger than mc. Therefore, it is problematic to treat mc of Tapered G-R law and Gamma
distribution as the maximum magnitude.Hirose et al. [2014, SSJ] estimated mc off Tohoku as 9.26 by
the truncated G-R law if χis 60% by applying the seismic moment conservation principle toearthquakes occurred along the Kuril-Kamchatka-Japan trench from 1977 to 2013.There is also Utsu
law with upper limit magnitude in addition to the truncated G-R law. In this study, we introduce
the formulation of seismic moment conservation principle about Utsu law, and apply it to the samedata set as Hirose et al. [2014, SSJ]. As the result, if assumed MT (χ = 60%) is correct, themaximum magnitude of events which will occur off Tohoku in the future is estimated as 10.03. Thereis a possibility that the Tohoku-oki earthquake is not always the largest event in this area.
Keywords: Seismic moment conservation principle, Maximum magnitude, Utsu law©2016. Japan Geoscience Union. All Right Reserved.

- SSS24-05 -SSS24-06

Japan Geoscience Union Meeting 2016

A Study on the Enhancing Earthquake Frequency in Northern Pakistan: Is the Climate
Change Responsible?
*Muhammad Usman1
1.Space Geodesy Research Section,Division of Earth and Planetary Dynamics, Department of Natural
History Science, School of Science, Hokkaido University
In northern Pakistan, the collision between Indian and Eurasian plates has resulted in theformation ofmany faults. The concentration of ruptures, in this regime, probably makes it sensitive to the
localizedchanges in the stress. The current climate changes have caused an increase in the rainfall andvariation in
the mass of glaciers, present in the northern Pakistan. The rainfall and glacial runoff has
potential to erode
and transport sediments thus can change the balance of load across faults. On the other hand,glacial massloss or gain also has potential of iso-static rebound or compression of crust, respectively. All
these factors
have been observed in the northern Pakistan. The seismic data of the duration 1965 to 2004 has beenobtained from Pakistan Meteorological Department (PMD) and the sedimentation data has been acquired
from Tarbela Dam Project (TDP). The study indicates a gradual increase in the earthquake frequency
forthe magnitudes 4.1-5.0(Mb). The epicental distributions show that these events gradually cluster inthecentral Karakorum and Hindukush areas. The depth analysis suggests the earthquakes with the foci 060km are gathering in the central Karakorum and shocks with depth 0-120 are clustering in the
Hindukush areas. The FMS study exhibits the dominance of normal faulting in the central Karakorum
after 1999 and these characteristics do not correspond with behavior of previous mapped Raikot
Fault,
lying in the vicinity. The known significant variables during the study period are the different
geologicalprocesses associated with climate change, which have potential to alter the load across faults andcanpossibly result in enhancing earthquake frequency by releasing stresses at some local scale.
Keywords: Climate change, glacial mass change,, rising earthquake frequency©2016. Japan Geoscience Union. All Right Reserved.

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Japan Geoscience Union Meeting 2016

Long-term predictability for the repeating earthquake with a few times recurrence using
the BPT model*Masayuki Tanaka1, Masami Okada1
1.Meteorological Research Institute
Event numbers of sequential recurrent large/medium earthquakes listed in seismic catalog are not somany, because they occur at long intervals. So, the probability of the next earthquakes must be
calculated with a small number of data. We are studying the predictability by the BPT model using
the 126 sequence of small interplate repeating earthquakes along the Japan Trench, which were used
for the experiment of prospective forecast in 2008. Calculation was carried out with a small numberof events. Events data was taken out in order of proximity from the last earthquake, by three,four, five and five or more.
We use BPT model to calculate the probabilities and three other models for comparison,(1) BPT-pin: BPT distribution model. The parameters: the mean recurrence intervals, the averagevalue of each series; the coefficient of variation, the median (α=0.367) of the values calculated
in five events for each series.
(2) LN-Bayes: Lognormal distribution model with Bayesian approach. Probability distribution ofrecurrence interval is given with inverse gamma prior distribution. The parameters of inverse gamma
are shape, φ=0.25 and scale, ζ=0.44.
(3) LN-SST: Lognormal distribution model base on the small sample theory.
(4) EXP-pin: Exponential distribution model. The parameter plugged is the sample mean.
The "Mean log-likelihood" mentioned below are used to score the forecast results.
Mean log-likelihood (MLL): Average of Ev*ln (P) + (1-Ev)* ln (1-P)
Here P means forecast probability for event and Ev means presence (Ev=1) or absence (Ev=0) of theevent. If the Mean log-likelihood is larger than those of the alternative, the model is considered
to be superior to the alternative one.
In Figure 1 the forecasts by four models become worse surely as the number of preceding events issmaller. The BPT-pin model is inferior to the other three of the statistical model. When the three
qualifying events, the score is poor in the Exp-pin model, and it is below the results of theprobability of 0.5 (MLL=-0.693).
Keywords: Repeating earthquakes, forecast, BPT model, Mean log-likelihood©2016. Japan Geoscience Union. All Right Reserved.

- SSS24-P01 -SSS24-P01©2016. Japan Geoscience Union. All Right Reserved.

Japan Geoscience Union Meeting 2016

- SSS24-P01 -SSS24-P02

Japan Geoscience Union Meeting 2016

How often do the abnormal phenomena witnessed just before 1946 Nankai earthquake appear(1)*Yasuhiro Umeda1, Satoshi Itaba1
1.Advanced Industrial Science and Technology
Abnormal phenomena such as well water decreases or sea level changes has been witnessed just before
the 1946 Nankai earthquake. In the Pacific Ocean coastal area of Shikoku from Kii peninsula, suchphenomena have been witnessed in 24 locations. It has been witnessed that about 2m decrease of well
water, maximum 3m lowering of sea level and about 0.5m of secondary undulation. It has been stable
weather before the main shock. Do the witnessed abnormal phenomena has appeared only just before
the main shock? Or do they occasionally appear? Based on the recent observation data, we examined
the frequency with that the same phenomena as witnessed just before the main shock. The water levelof three wells which have been reported the decreased water before the main shock have been
observed continuously by AIST. In recent two years data, it was not found that the well water
steeply decreases by more than 2m. We have searched the sea level departure at Kushimoto, Muroto
cape and Kochi, on the JMA website. In 2003 - 2014, we could not find the sea level departure ofmore than -2m. The secondary undulations at Muroto cape were checked on the JMA website. In
2006-2014, there were 17 times of the secondary undulations more than 0.5m. All cases were causedby the weather. Within this survey, we could not find the similar abnormal phenomena which were
witnessed just before the main shock.
Keywords: 1946 Nankai earthquake, witness©2016. Japan Geoscience Union. All Right Reserved.

- SSS24-P02 -SSS24-P03

Japan Geoscience Union Meeting 2016

Empirical forecast of mainshocks based on foreshock activities- Applied to the specific three regions and inland area of Japan *Kenji Maeda1, Fuyuki Hirose1
1.Meteorological Research Institute
1. Introduction
Generally it is quite difficult to distinguish foreshocks from background seismicity before amainshock occurs. However, it is known that some activities like swarms tend to be followed bylarge earthquakes. We have investigated statistical features of swarm-like activity and searched
for the best parameters to define foreshocks. So far, we have found that such defined foreshock
activities are particularly effective for specific three regions in Japan: regions along the Japan
trench, off the Izu peninsula region, and in the north-central Nagano prefecture, and proposed bestparameters for each regions to define foreshocks. In this study we report the current status ofprediction performance for three regions basing on the latest data. Besides, we also demonstrate
the preliminary results of prediction performance for the inland area of Japan using the same
parameters estimated for the north-central Nagano prefecture.
2. Method
The method to search for parameters for foreshocks that present high prediction performance
consists of four steps. 1) To eliminate small aftershocks from the original data. 2) To define
foreshock candidates satisfying the condition that earthquakes of count Nf with magnitude >= Mf0
occur in the segment of the size of D x D degree (latitude x longitude) during the period of Tf
days. 3) To set the alarm period of Ta days during which a mainshock is expected to occur after aforeshock candidate is found. 4) To search for the values of D, Mf0, Tf, Nf and Ta which give highprediction performance for mainshocks with M >= Mm0 by the grid search method. The prediction
performance is measured mainly by dAIC that is defined as the difference of AIC for a stationary
Poisson model and a model based on a foreshock activity, and additionally by alarm rate (AR: thefraction of mainshocks alarmed), truth rate (TR: the fraction of foreshock candidates followed by amainshock), and probability gain (PG: the ratio of mainshock occurrence rate in the predicted
space-time to background occurrence rate).
3. Data and Results1) Along the Japan Trench
By applying the above method to the earthquakes with M >= 4.0 and depth <= 100 km in three regions
along the Japan trench, i.e., off Iwate, off Miyagi and off Ibaraki, cataloged by JMA during theperiod from 1961 through 2010, we obtained the best parameters for foreshocks as D=0.5 degree, Mf0=5.0, Tf=10 day, Nf=3, and Ta=4 days to predict mainshocks with M>=6.0. The prediction performancefor the latest period from 1961 to 1/31/2016 is expressed as AR=27% (=13/48) and TR=22% (=17/77).
2) Off the Izu Peninsula
Using earthquakes with M >= 3.0 and depth <= 50 km off the Izu peninsula regions during the period
from 1977 to 6/31/2013, we obtained the best parameters for foreshocks as D=0.2 degree, Mf0=3.0,
Tf=3 day, Nf=3, and Ta=5 days to predict mainshocks with M>=5.0. The prediction performance from1977 to 1/31/2016 using the above parameters is expressed as AR=68% (=44/65) and TR=22% (=43/195).
3) In the North-central Nagano Prefecture
Using earthquakes with M >= 2.0 and depth <= 30 km in the north-central Nagano prefecture during
the period from 1998 through 2014, we obtained the best parameters for foreshocks as D=0.1 degree,
Mf0=2.0, Tf=1 day, Nf=5, and Ta=5 days to predict mainshocks with M>=5.0. The prediction
performance from 1998 to 1/31/2016 using the above parameters is expressed as AR=45% (=5/11) and©2016. Japan Geoscience Union. All Right Reserved.

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Japan Geoscience Union Meeting 2016

TR=12% (=8/69).
4) Inland of JapanAs a preliminary calculation, we apply the parameters obtained for the north-central Nagano
prefecture, i.e., D=0.1 degree, Mf0=2.0, Tf=1 day, Nf=5, and Ta=5 days for mainshocks with M>=5.0,
to the inland area of Japan except for Izu. The prediction performance obtained for the period from1977 to 1/31/2016 is expressed as AR=11% (=9/79) and TR=1.8% (=11/607).
Keywords: earthquake prediction, performance, foreshocks, statistics, empirical relation, Japaneseinland area

©2016. Japan Geoscience Union. All Right Reserved.

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Japan Geoscience Union Meeting 2016

The Predicting earthquakes/estimation and the historical tsunami.
*Masaru Nishizawa1
1.none1. The historical tsunami in the wilderness researcher has predict the 2011 TOHOKU Great
Earthquake. At present it is difficult to make an accurate prediction on the occurrence ofearthquake. But these historical tsunami is effective method to a rough prediction.
2. I believe that the electromagnetic wave is most effective method to an accurate prediction on
the occurrence of earthquake.
Reference.
(1)YUUGI IINUMA: Historical Tsunami of Sendai Plain. 1995
Keywords: IINUMA YUUGI, Historical tsunami of Sendai plain, Predicting earthquakes, Petition,
TOHOKU district great earthquake, Public office©2016. Japan Geoscience Union. All Right Reserved.

- SSS24-P04 -SSS24-P05

Japan Geoscience Union Meeting 2016

The To-Nankai E.q. is previous and the Nankai E.q. occurs after it or with it, Elucidationof that mechanism*Hirofumi Mase1
1.noneI explained that the right-turn of slab under Kii Peninsula is the To-Nankai Earthquake, and thatthe big earthquake which neighbors on it isn't also a simple plate boundary earthquake(1)(2)(3). I
studied details around the turn-center this time. That was the drive part of the first half of the
Nankai Earthquake, and of the mechanism that that can't explode first than the To-Nankai. (Pleaserefer to the Fig.)(I call the subducting plate or slave the Lower, and call the part upper than it
the Upper.)
The power that the mantle which flows to the east relatively pushes the edge of the Lower directly
and makes the Lower turn to the right is the turn-drive-force(1). The reactions of it occur widely,but symbolic 6 are representation of all(Fig.1). The west(Area A) from the turn axis(fulcrum) is
east-west extension area certainly by the reaction. At the east(Area B) from the fulcrum, doing a
nose-dive from the shallow place and after forming the almost horizontal part, shocks will approach
the Lower and be the part of make-landing(Sec.y5-Sec.y8). The Lower crawling up with turning rubbs,
involves and assimilates the Upper that is rotated in advance. The horizontal part of preparations(turning face) will be formed so. I indicated the turning face at yellow coloring territory andindicated the part of make-landing at gray coloring territory (an orange broken line, centerline)(Fig.2). At the more east(Area C) I can't check the part of make-landing(Sec.y9-Sec.y10). Because
the turn in the Lower is moderate (radius large) here, I think the Upper isn't captured.
High-density "High-speed body" touches the peninsula and goes through the Upper and Lower(eachFig. referring)(5). That's a man-shaped who consists of head and body, and depth 40km is neck.
There will be time when movement and pressure in Area B shaves or improve, conversely, the"High-speed body" in existence. I regard the neck(Fig.1,depth 40km blue coloring) as the core whichstays while thinning. Because the Lower is divided into a inside turn(Area B) and a outsideturn(Area C) by collision with the core, and the outside turn is making a wide turn(Fig.1, black
broken line arrow), the Lower separate inevitably in east and west at the south from the core. I
think the rub of two boards causes pressure and increases density like an rubbing face of astone-hand-mill and I think the discoid head is formed by it. But the head isn't plane symmetry indepth 25km(Fig.1,2,loop contour). Material partiality to the south and west is seen more in theupper part of the head.
Red arrows of Fig.2 are the observational data(7) by which the inside turn and the outside turnare surely indicated. The To-Nankai Earthquake was a right turn in the large-scale area which has
started in the red asterisk from crushing in the Lower(1)(Fig.1). This is the outside turn. The
real inside turn that mostly depends on interference of the rubbing face of the stone-hand-millrequires facts that the Lower can turn and advance to a shallow part. In other words,
pressing-force-reduction from the outside-turn-part and preceding-destruction in the shallow partare wished for. Is there something equivalent to this inside turn besides The Nankai Earthquake
which has started from the blue asterisk 2 years later of the To-Nankai(8)(9)?
(1)MASE/JpGU2014/SSS29-P10(2)MASE/SSJ2014FALL/S08-P11(3)MASE/JpGU2015/SSS31-P15(4)AIST/Visualizatio
n system for subsurface structures/all-Japan hypocenter catalog by the JMA/1995-2015/above
M1(5)AIST/same to(4)/tomography data by Abdelwahed and Zhao (2007)dVp (6)JHOD,JCG/Seafloor
Topography of the Plate Boundaries (7)GSI Home Page/ GEODETIC SURVEY/Crustal Movement inJapan/Long-term Information/Horizontal2005/10-2015/10fixed stn.NAKAMURA (8)(9)indicated on the©2016. Japan Geoscience Union. All Right Reserved.

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Japan Geoscience Union Meeting 2016

drawing©2016. Japan Geoscience Union. All Right Reserved.

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