Proceeding of International Conference On Research, Implementation And Education Of Mathematics And Sciences 2014, Yogyakarta State University, 18-20 May 2014

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“JOKO TINGKIR” FOR DECISION MAKING ON REALTIME TSUNAMI WARNING SYSTEM

Madlazim1) , Supriyono 2) , Masturyono 3) , Thomas Hardy 4) , Karyono 5)

1) and 2) Physics Department of Faculty of Mathematics and Natural Science, Surabaya State University (UNESA)
3), 4) and 5) Indonesian Agency for Meteorology, Climatology and Geophysics (BMKG) madlazim@fmipa.unesa.ac.id

Abstract

Most of Tsunami Early Warning System has used earthquake magnitude as indicator of tsunami. However, magnitude is not good indicator for Tsunami-genic Earthquake. Purpose of this study is to test the validity of Joko Tingkir computer program for decision-making on a tsunami early warning system in real time. The Joko Tingkir computer program implemented a Tsunami Faulting Model (TFM). TFM uses the principle that the tsunami affected by the length and width of earthquake rupture. Both can be represented by the duration of rupture (Tdur) or Exceed 50 second duration (T50Ex) and the dominant period (Td). TFM has been implemented by Joko Tingkir computer program. Based on the test results of Joko Tingkir computer programs in real time for 146 earthquakes (magnitude 5 to 6.9) and offline testing at FMIPA UNESA laboratory for 33 earthquakes (magnitude 6.5 to 9.3) can be concluded that the Joko Tingkir computer program can estimate Tdur, T50Ex and Td simultaneously, accurately and quickly, so the Joko Tingkir computer program can be used for decision making on real time Tsunami Early Warning System.

Key word: Tsunami faulting model, rupture duration, exceed duration 50 second, dominant period, Joko Tingkir computer program

Introduction

Quick and accurate information of the earthquake source parameters is a prerequisite for building an early warning system of earthquake and tsunami. The types of research that can provide information hypocentral measurements, magnitude and other parameters that affect the tsunami provide very valuable information. Therefore, the methods are needed qualified output so quickly and accurately that further implemented in modern seismological network about providing information that can be automatically and in real time just after the earthquake.
Some methods and applications are available and have been proposed and has been applied to determine the source parameters of earthquakes for tsunami early warning system, among othersseimic magnitude (Mw) is found to be a good discriminant for many, past, tsunamigenic earthquakes, but not all, especially not for so-called ‘tsunami earthquakes’, which, by definition, cause larger tsunami waves than would be expected from their Mw (e.g. Satake, 2002; Polet & Kanamori, 2009; Lomax & Michelini, 2011). The discrepancy for these earthquakes can be related to rupture at shallow depth where μ can be a very low, anelastic deformation such as ploughing and uplift of sediments may occur, and the fault surface may be nonplanar with splay faulting into the accretionary wedge (e.g. Lay & Bilek 2007). One or more

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of these effects can result in an underestimate by Mw of an effective LWD value by a factor of four or more relative to the value needed to explain the observed tsunami waves (Okal 1988; Satake 1994; Geist & Bilek 2001; Lay & Bilek 2007; Polet & Kanamori 2009; Lomax & Michelini, 2011). Several analysis of teleseismic, P-wave seismograms (30o–90o great-circle distance; GCD), Lomax & Michelini (2009) have shown that a high frequency, apparent rupture-duration, T0, greater than about 50 s forms a reliable discriminant for tsunamigenic earthquakes (Fig. 1). Lomax & Michelini (2009) exploit this result through a direct, duration-exceedance (DE) procedure applied to seismograms at 10o–30o GCD to rapidly determine if T0 for an earthquake is likely to exceed 50–55 s and thus to be a potentially tsunamigenic earthquake and Madlazim (2013) resulted that of the present study and the analysis of the seismic parameters helped explain why one event generated a tsunami, while the other one did not. .
This study, we present Joko Tingkir program as a application of Tsunami Faulting Model (TFM) by implementing direct procedure for assessing tsunami potential (Lomax & Michelini, 2009; 2011; 2012, Madlazim, 2011; 2012; 2013) which combines rupture duration (Tdur) with a measure of the dominant period (Td) and duration exceedance 50 seconds (T50Ex) on the local velocity records simultaneously for real time early warning system. Tdur, Td and T50Ex are simple to measure on observed, P-wave seismograms and can be related to the critical parameters L, W, D and depth needed for assessing tsunami potential (Lomax and Michelini, 2011). The direct procedure was implemented on Joko Tingkir Program.

Method and Program Description
Joko Tingkir program is a scropt program to calculate three parameters as indicator of earthquake generating tsunami. The parameters are Tdur (Rupture duration), Td ( Dominant Period), T50Ex, and the Products (Tdur*Td, T50Ex*Td) simultaneously. Tdur is associate/equivalent with the length of the rupture zone Td is associated/equivalent with the width of the rupture zone T50Ex is associate/equivalent with the length of the rupture zone (better estimate than Tdur). The products are associate with the area of the rupture zone  Strength Scale of the earthquake source.
Joko Tingkir can directly read the data seismograms in miniseed format by using SeisGram2K software , so that the software is faster to read seismograms in real time, without the need to first convert into other formats or SAC. Computational speed of the earthquake parameters are dependent on the amount of data processed. For example, if the amount of data that is processed vertical component seismogram there were 20 recorded by 20 stations, then the time required by the "Joko Tingkir" for computing these parameters approximately 18 seconds. Output "Joko Tingkir" in addition to a mean value of Tdur , Td, T50Ex, Td * T50Ex also provide value Tdur , Td and T50Ex for each station , so that the user can evaluate whether Tdur, Td and T50Ex at each of the stations is valid or not , homogeneous or not when compared with the value Tdur, Td and T50Ex on most other stations . If the value Tdur , Td, T50Ex and Td * T50Ex are more than critical value, the tsunamigenic earthquake and vice versa . By using the "Joko Tingkir", a tsunami early warning system could be announced less than 5 minutes after the earthquake occurred, so that the public and relevant agencies have more time to prepare evacuation. The flowchart of the Joko Tingkir program for real time system presented on figure 1 with criteria of tsunami potential shows on figure 2..

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Proceeding of International Conference On Research, Implementation And Education Of Mathematics And Sciences 2014, Yogyakarta State University, 18-20 May 2014

DESIGN IMPLEMENTATION

InaTEWS

TRIGER Auto Loc

Input Managemen Unit

Joko Tingkir Calculate : Tdom,Td, T50EX, Td*Td, Td*T50EX

Test The Criteria

DISPLAY 1.Location Map 2.EQ Parameter
3.Tsunami Indicator 4.Warning

CRITERIA OF THE POTENTIAL TSUNAMI

Parameters
	Criteria
	Yes
	No
	
Rupture Dur (Tdur)
	> 65 s
	v
		
T Dominan (Tdom)
	> 10 s
	v
		
T50EX
	> 1 s
	v
		
(Tdur * T dom)
	650
	v
		
(Tdom * T50EX)
	>10
	v
		
Sumary
	Potential Generating Tsunami

Plotting of Results Test

The last step is the plotting of the Joko Tingkir results, in particular the Tdur, Td, T50Ex, T50Ex*Td and Tdur*Td solution and the decision making of the earthquake generate tsunami or not in about 4 minuts after event (Fig. 2).

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Madlazim et.al. / Joko Tingkir for …	ISBN 978 – 979 – 99314 – 8 – 1

Figure 3. Test Result of Joko Tingkir program real time running

Base on result real time and offline test for 171 earthquakes, criteria for tsunami potential; Tdur, Td, T50Ex, T50Ex*Td are feasible for tsunami early warning system. result for showing that 96.5 % of 171 events tested are consistent with the criteria set for the validation test. The criteria used in this validation test are Td*T50Ex > 10 and Td*Tdur > 650 for

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Proceeding of International Conference On Research, Implementation And Education Of Mathematics And Sciences 2014, Yogyakarta State University, 18-20 May 2014

earthquake generating tsunami. The total time used to get the result is about 4 minutes, if the Trigger taken from automatic location from InaTEWS.
Conclusions

JOKO TINGKIR program has been implemented in the real time data flow within the InaTEWS network for validation purpose. Preliminary result for showing that 96.5 % of 171 events tested are consistent with the criteria set for the validation test. The criteria used in this validation test are Td*T50Ex > 10 and Td*Tdur > 650 for earthquake generating tsunami. The total time used to get the result is about 4 minutes, if the Trigger taken from automatic location from InaTEWS. So, the Joko Tingkir program can be considered for decision making on real time Tsunami Early Warning System

Acknowledgments

The Research and Development of Indonesian Agency for Meteorology, Climatology and Geophysics (BMKG) provided access to realtime Joko Tingkir aplication used in this research. I thank all the people who install, operate and maintain the seismic stations in Indonesia. I thank Anthony Lomax and Michelini who gave us guidance in understanding the rupture duration, dominant period and T50Ex estimation and in applying the SeisGram2k software to estimate these parameters (http://alomax.free.fr/software.html). Our discussions with them were beneficial. Finally.

References

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