A study on Hypocenter Determination of Earthquakes at Izu Tobu District

By

ÇOMOĞLU, Mustafa

Geophysical Engineer, Seismologist

Bogazici University Kandilli Observatory and Earthquake Research Institute

National Earthquake Monitoring Centre,TURKEY

Advisor: Associate Professor Yuichi MORITA

ERI, University of TOKYO

DISASTER RISK MANAGEMENT TECHNOLOGY ON VOLCANIC ERUPTION, DEBRIS FLOW AND LANDSLIDE

INDIVIDUAL PROGRAM REPORT (MAY-AUGUST 29th 2008)

At University Of Tokyo, Earthquake Research Institute

Geology And Petrology Group “Volcano Research Center”

1

Motivation of my individual study

My job in my country (TURKEY)

To locate earthquake hypocenter using zSACWin,

The software based on HYPO71 but I did not

know the process of that software in detail.

Purpose of my individual study

To learn the algorithm of the software.

To learn software programming.

Exercising to make program.

2

3

MY ROUTINE JOB (READING P AND S ONSETS)

RESULTS “THE LAST YEARS SEISMICITY”Hypocenter distribution of from year 2005 to June 2008

Seismic Stations: 119 (BB: 88, SP: 31)

4

(12.636 events is mapped )

5

If we focus on the volcanic areas;

Eastern Part of TurkeyWestern Part Of Turkey

Central Part Of Turkey

• Red triangles indicate

volcanic regions

• White circles indicate

earthquakes.

6In these diagrams , we noticed that there are some seismic anomaly around Suphan Mountain. It s

indicated by orange circles. However due to the lack of seismic station network coverage (look at Map

1.1 and Map 1.2) we cannot get a chance to focus on volcano related seismicity in that area.

The Earthquake Hypocentre coordinates has been turned 32 degree in clockwise

due to the positions of the Volcanic Mountains

Name of

volcanoes

N32E

S32W

SUPHAN

NEMRUT

GIREKOL

TENDUREK

ARARAT

Map 1.2 Stations distribution around volcanic area at eastern part of Turkey

7

SUPHAN

:KOERI SEISMIC STATIONS

400 km0

In this individual program;

•TARGET 1) To understand the processes of hypocenter

determination

2) Programming (Fortran)

3) Effect of the station Correction

•DATA : Earthquake swarm in Izu Tobu district, JAPAN

(2006-03-25 - 07-20) by ERI.

•SOFTWARE : HYPO71 by Lee et al.

•COMPILER : Intel Visual Fortran 10.1 with MKL Library used to revise

program sources due to our necessities. (Provided by JICA)

•PLATFORM : Microsoft Visual Studio 2005

8

9

UNDERSTANDING

HYPO71

EARTHQUAKE

LOCATING

SOFTWARE

HYPO71.for

OPEN THE INPUT AND OUTPUT FILES

DEFINE INPUT AND OUTPUT FILES

INPUT FILES OUTPUT FILES

eg. HYPO71.INP HYPO71.SUM

HYPO71.PUN

HYPO71.BRI

INPUT2.for:

INPUT PHASE LIST

INPUT1.for:

INPUT STATION LIST,CRUSTAL MODEL

SUMOUT.for

END PROGRAM

SINGLE.for: Processes one earthquake at a

time

SET UP A TRIAL HYPOCENTER AZWTOS.fo

r

ARVDRV.

for SWMREG.f

orALIOUT.for

MISING.f

orFPLOT.for

XFMAGS0.f

or

SORT.fo

r

SORT.fo

r

(O

RIG

INA

L H

YP

O7

1)

FL

OW

CH

AR

T

HYPO71

COMPUTE SUMMARY OF TRAVEL TIME RESIDUALS

COMPUTE RMS AT AUXILIARY POINTS

CHECK FOR MULTIPLE SOLUTIONS OF THE SAME EARTHQUAKE

SINGLE.for: This Routine processes one earthquake at a time and involves these steps;

SET UP A TRIAL HYPOCENTER, The first trial epicenter is normally set to be latitude and longtitude of the station with the earliest P

arrival.the first trial focal depth is set equal to that given in the control card, unless specified on the instruction card.The First trial origin time is

set so that the average residual of P and S arrivals is zero….

Compute error estimates

AZWTOS.for

AZIMUTHAL

WEIGHTING OF

STATIONS BY

QUADRANTS

ARVDRV.for

COMPUTE TRAVEL

TIME AND

DERIVATIVES

FROM CRUSTAL

MODEL

SWMREG.for

COMPUTES

GEIGER

ADJUSTMENTS

BY STEP-WISE

MULTIPLE

REGRESSION OF

TRAVEL TIME

RESIDUALS

ALIOUT.for

OUTPUT

HYPOCENTER

MISING.for

CHECK MISSING

STATIONS

FPLOT.for

PLOT

FIRST-MOTION

DIRECTIONS OF

THE LOWER

FOCAL

HEMISPHERE IN

EQUAL AREA

PROJECTION,

WHERE C

DENOTES

COMPRESSION

AND D DENOTES

DILATATION

XFMAGS0.for

COMPUTE

X-MAGNITUDE

AND

F-MAGNITUDE

SORT.for

This is a utility

subroutine to sort

xi,i=1,..N by

increasing value.

ANSWER.for

PRINT

INTERMEDIATE

RESULTS OF

REGRESSION

ANALYSISSORT.for

This is a utility

subroutine to sort

xi,i=1,..N by

increasing value.

..

…

10

RESET TEST(02)=150.0RESET TEST(03)=0.5RESET TEST(06)=0.25RESET TEST(11)=25.RESET TEST(13)=5.0

YLVX4034.00N 2922.37E 829 -0.18YOZ 3938.30N 3518.92E1422 0.15YSFR4036.37N 2914.51E 115YTSV4037.60N 2905.24E 70YZL 4041.42N 2952.04E 75ZYBG4023.40N 2847.69E 70EARA3458.28N13907.10E-145IOB13452.43N13912.39E-985IOB23456.15N13916.18E-1330IOB33457.70N13913.02E-1170ITHH3456.80N13905.13E-160JIZF3455.00N13859.63E 263KAMA3455.71N13903.65E 175KNIH3505.12N13858.67E-100KWZH3446.99N13858.20E 28NHTS3502.52N13910.01E -84NITO3457.14N13908.30E -84NJIZ3454.97N13859.65E 263NMNZ3508.74N13909.01E-114NNRY3503.79N13857.58E -91NRYH3503.79N13857.58E -91SZJH3458.54N13854.77E 47

4.035 0.0006.104 5.0006.320 20.0007.500 40.000

5. 50. 750. 1.73 4 1 5 2 1 0 1NITOIP 1 060325034846.332 47.74IS 1 ITHHIP 1 060325034846.523 48.01IS 1 EITOIP 1 060325034846.561 48.17IS 1 EKAWEP 2 060325034846.577 48.12IS 1 EFTOEP 2 060325034846.723 48.36IS 1 KAMAEP 3 060325034846.761 48.48IS 1 EOKVEP 3 060325034846.781 48.46IS 1 NJIZEP 3 060325034847.652 49.94IS 1 JIZFEP 3 060325034847.665 EHOKEP 3 060325034848.019 50.50IS 1 EATAEP 3 060325034848.198 NNRYEP 3 060325034848.372 51.12IS 1 EICYEP 3 060325034848.378 NRYHEP 3 060325034848.429 51.17IS 1 SZJHEP 3 060325034848.551 51.66IS 1

Velocity Structure

Station Data

Onset times of each station.

Some control Parameters

11

HYPO71 Input File

12

HYPO71 OUTPUT FILES “*.SUM”

P (Reading )

P (Calculated)

P Residual

S (Reading )

S (Calculated)

S Residual

*In this study *.SUM Files used to calculate Mean Residuals and Re-Location

STATION CORRECTION

The HYPO71 that used in my job does not use

the station correction

Effect of the station correction is distinct in the

case of local earthquakes, because the structure

just beneath the station affects much on

estimated hypocenters.

Using Japanese data I evaluate the effect of the

station correction. (I need data conversion from

Japanese system to HYPO71 system)

13

Tectonic background around the Izu Peninsula

North margin of Philippine Sea Plate. Tectonic stress is P axis : NW-SE T axis : NE-SW.

There are many mono-genetic volcanoes at the Izu Peninsula.

There are many earthquake swarms accompanied by ground deformation.

14

Earthquake swarms at Izu Peninsula

Frequency of observed earthquakes at Kamata (JMA)

(Submarine eruption)

Mo

nth

ly fre

qu

en

cy

Activity declines

since 1998

15

The submarine eruption in 1989.

Oshima et al. (1991)

July 13, 1989

Unique eruptive activity among latest 50 years

16

17

SEISMIC STATIONS NETWORK AROUND IZU AREA

17

18

Velocity Model

Lay

ers

P Wave

Velocity

(Km/s)

Depth

(Km)

1st 2.600 0.000

2nd 4.100 0.300

3rd 5.200 2.100

4th 5.750 6.000

Previous study

This study

19

The following maps show that 4256 Earthquakes at IZU TOBU area which located by

WinSystem (Japanese software) and HYPO71

1- 4256 Earthquakes located by HYPO71* 2- 4256 Earthquakes that located both by

HYPO71* and WinSystem (Dark blue circles are

WinSystem Earthquake Locations

MAPPING OF HYPOCENTRE DETERMINATION RESULTS

19

Residual distributions of some stations in case of the HYPO71

20

0

50

100

150

200

250

-1 -0.5 0 0.5 1

EITO

0

50

100

150

200

250

-1 -0.5 0 0.5 1

NRYH

0

20

40

60

80

100

120

140

160

-1 -0.5 0 0.5 1

KNIH

0

20

40

60

80

100

120

140

160

180

200

-1 -0.5 0 0.5 1

SZJH

0

20

40

60

80

100

120

140

-1 -0.5 0 0.5 1

MNZH

EITO NRYH KNIH

SZJH MNZH

21

Residual distributions of some stations in case of the HYPO71

0

50

100

150

200

250

300

350

400

450

500

-1 -0.5 0 0.5 1

KAMA

0

20

40

60

80

100

120

140

160

180

-1 -0.5 0 0.5 1

EATA

0

20

40

60

80

100

120

140

-1 -0.5 0 0.5 1

EHOK

0

10

20

30

40

50

60

70

-1 -0.5 0 0.5 1

KWZH

KWZH

KAMA EATA EHOK

22

HOW TO ESTIMATE STATION CORRECTION

CALCULATING P-S WAVE “MEAN RESUDIALS”

“resmean” fortran source code helps us to

check each events and each stations

residuals in *.SUM files which produced

by HYPO71 then to calculate mean

residuals for each stations.

ST N

AM

E

LAT LONG ELV.

P M

EAN

RES

.

S M

EAN

RES

.

NU

MB

ER O

F P

REA

DIN

GS

NU

MB

ER O

F S

REA

DIN

GS

EARA 3458.28N 13907.10E -145 0.03 -0.06 1619 813

EATA 3506.95N 13904.36E 290 -0.01 0 2582 0

EFTO 3454.46N 13908.14E 75 0.08 0.13 3259 2083

EHAT 3502.30N 13910.35E 46 0.11 0.11 2499 882

EHOK 3451.18N 13902.18E 890 0.15 0.25 2687 1295

EICY 3454.40N 13855.81E 210 0.02 0 2374 0

EITO 3456.49N 13904.48E 204 -0.38 -0.66 3986 2852

EKAW 3457.29N 13908.54E 5 0.08 0.23 4255 2998

EKWZ 3445.95N 13859.21E 65 -0.13 -0.53 813 437

EOKV 3456.42N 13903.62E 170 0.03 -0.05 4103 3549

IOB1 3452.43N 13912.39E -985 -0.04 0.25 272 86

IOB2 3456.15N 13916.18E -1330 0.07 1.28 329 86

IOB3 3457.70N 13913.02E -1170 -0.17 0.37 634 166

program resmeanreal*8 alat,aloncharacter dtx*80,stnm*4,cla*1,clo*1open(20,file='stname.inp')open(21,file='stname.out')

10 read(20,2000,end=70) stnm,alat,cla,alon,clo,ielvif(stnm.eq.' ') goto 70

2000 format(2x,a4,f7.2,a1,f8.2,a1,i5)np=0ns=0pt=0.0st=0.0

open(10,file='I:\...\jpinp.sum')read(10,1000) dtx

1000 format(a80)30 read(10,1000,end=50) dtx

if(dtx(1:4).ne.stnm) goto 30write(6,'(a80)') dtxread(dtx(25:25),'(i1)') ipif(ip.gt.0) thenread(dtx(38:43),'(f6.2)') pxnp=np+1pt=pt+px

endifread(dtx(54:54),'(i1)') isif(is.gt.0) thenread(dtx(67:72),'(f6.2)') sxns=ns+1st=st+sx

endifgoto 30

50 close(10)if(np.gt.0) thenpt=pt/float(np)

elsept=0.0

endifif(ns.gt.0) thenst=st/float(ns)

elsest=0.0

endifwrite(6,600) stnm,pt,np,st,ns

600 format(a4,2(f8.2,i5))write(21,2100) stnm,alat,cla,alon,clo,ielv,pt,st,np,ns

2100 format(2x,a4,f7.2,a1,f8.2,a1,i5,2f6.2,2i6)goto 10

70 close(20)close(21)stopend

This software is written, for calculating Station corrections for each station by using the P and S wave residuals of each event

Use the HYPO SUMMARY FILE *.SUM

•Sample data produced by resmean.for

RESMEAN

23

What we changed on INPUT2.for Subroutine

ADDING STATION CORRECTIONS

23

24

INPUT2.for:

INPUT PHASE LIST

INPUT1.for:

INPUT STATION LIST,CRUSTAL MODEL

SUMOUT.for

END PROGRAM

HYPO71.for

OPEN THE INPUT AND OUTPUT FILES

DEFINE INPUT AND OUTPUT FILES

INPUT FILES OUTPUT FILES

eg. HYPOMC.INP HYPO71.SUM

HYPOMC.PHS HYPO71.PUN

HYPOMC.STA HYPO71.BRI

SINGLE.for: Processes one earthquake at a time

SET UP A TRIAL HYPOCENTER

AZWTOS.for ARVDRV.for SWMREG.for

ALIOUT.for

MISING.for

FPLOT.for

XFMAGS0.for SORT.for

SORT.for

Station Correction Data

added (for both P and S

waves)

Contains CRUSTAL

MODEL

Contains PHASE

DATAContains STATION

NAME,LON,LAT,EL

EV, STATION

CORRECTIONS

HYPOMC

FLOWCHART

24

HYPOMC

25

NEW *.INP File for HYPOMC

CRUSTAL MODEL

NEW *.STA File for HYPOMC

produced by RESMEAN.for NEW *.PHS File for HYPOMC

NECESSARY FILES TO RUN HYPOMC

Iterative estimation of station correctionHypocenter determination

without station correction

Calculate mean residuals

Hypocenter determination

With station corrections

1st iterationHypocenter determination

With station corrections

Calculate mean residuals

2nd iteration

26

HYPO71

RESMEAN

HYPOMC

RESMEAN

HYPOMC

.

.

.

.

.

.

27

WHY I SEPARATED HYPO71 INPUT FILE 3

PART?

1.The 1st part ( *.inp ) contains some test

variables and Crustal Velocity Model. In this way

we can easily switch to another velocity model by

changing this file if we need to use another

velocity model.

2.The 2nd part ( *.sta ) contains stations

information (latitude, longitude, elevation and

calculated station correction values. For each

iteration this file is produced by RESMEAN.for

again.

3.The last part ( *.phs ) contains events data.

28

0.145

0.15

0.155

0.16

0.165

0 2 4 6 8

EITO P

0

0.1

0.2

0.3

0.4

0 2 4 6 8

EITO S

0

0.2

0.4

0.6

0 2 4 6 8EHOK P

0

0.2

0.4

0.6

0.8

0 2 4 6 8EHOK S

0

0.02

0.04

0.06

0 2 4 6 8KAMA P

0.155

0.16

0.165

0.17

0.175

0.18

0 2 4 6 8

KAMA S

7 ITERATION APLLIED TO SUM FILE

P onsets S onsets

EHOK

EITO

KAMA

Station

X- Axis : Number of iteration Y-Axis : Standart deviation

29

0.076

0.078

0.08

0.082

0.084

0.086

0 2 4 6 8

MNZH P

0

0.05

0.1

0.15

0.2

0.25

0 2 4 6 8

MNZH S

0

0.05

0.1

0.15

0 2 4 6 8KWZH P

0

0.1

0.2

0.3

0.4

0 2 4 6 8KWZH S

0

0.05

0.1

0.15

0.2

0.25

0 2 4 6 8

KNIH S

0

0.02

0.04

0.06

0.08

0 2 4 6 8

KNIH P

MNZH

KWZH

KNIH

P onsets S onsetsStation

X- Axis: Number of iteration Y-Axis : Standart deviation

7 ITERATION APLLIED TO SUM FILE

30

0

0.02

0.04

0.06

0.08

0.1

0 2 4 6 8

NRYH P

0.53

0.54

0.55

0.56

0.57

0.58

0 2 4 6 8

NRYH S

0.124

0.125

0.126

0.127

0.128

0.129

0.13

0.131

0 2 4 6 8

SZJH P

0.106

0.108

0.11

0.112

0.114

0.116

0 2 4 6 8

SZJH S

0.085

0.09

0.095

0.1

0 2 4 6 8

EATA P

EATA

SZJH

NRYH

P onsets S onsetsStation

X- Axis: Number of iteration Y-Axis : Standart deviation

7 ITERATION APLLIED TO SUM FILE

31

Residual distributions of some stations

before and after iteration.

0

50

100

150

200

250

300

-1 -0.5 0 0.5 1

EITO-BEFORE EITO-AFTER

0

100

200

300

400

500

600

-1 -0.5 0 0.5 1

NRYH-BEFORE NRYH-AFTER

0

50

100

150

200

250

300

-1 -0.5 0 0.5 1

KNIH-BEFORE KNIH-AFTERX Axis: Residuals

Y Axis: Number of events

EITO

3986 eventsNRYH

3182 Events

KNIH

2117 Events

32

Residual distributions of some stations

before and after iteration.

0

20

40

60

80

100

120

140

160

180

-1 -0.5 0 0.5 1

MNZH-BEFORE MNZH-AFTER

0

10

20

30

40

50

60

70

80

90

-1 -0.5 0 0.5 1

KWZH-BEFORE KWZH-AFTER

0

100

200

300

400

500

600

700

800

-1 -0.5 0 0.5 1

KAMA-BEFORE KAMA-AFTER

X Axis: Residuals

Y Axis: Number of events

KAMA

4324 Events

MNZH

1441 EventsKWZH

1371 Evens

33

Residual distributions of some stations

before and after iteration.

0

50

100

150

200

250

300

-1 -0.5 0 0.5 1

EHOK-BEFORE EHOK-AFTER

0

50

100

150

200

250

-1 -0.5 0 0.5 1

SZJH-BEFORE SZJH-AFTER

0

50

100

150

200

250

300

-1 -0.5 0 0.5 1

EATA-BEFORE EATA-AFTER

X Axis: Residuals

Y Axis: Number of events

EATA

2582 Events

EHOK

2686 Events

SZJH

1940 Events

34

Seismicity around Izu Tobu district between 2006-03-25 and 07-20

(Without Adding Station Correction)

35

Seismicity around Izu Tobu district between 2006-03-25 and 07-20

(With Station Correction)

Seismicity with Depth around Izu Tobu district between 2006-03-25 and 07-20

(Without Adding Station Corrections)

36

37

Seismicity with Depth around Izu Tobu district between 2006-03-25 and 07-20

(With Station Corrections)

38

CONCLUSIONS

o I understood the processes of HYPO71 completely.

and I can revise the software freely.

o I tried to add the station corrections into the original

HYPO71 source code.

o I understood the effect of the station correction for

earthquake swarms. The scattered hypocenters

concentrate in narrow regions after adding

station correction.

o I will apply this method to the local events in

TURKEY .

39

ありがとうございましたT

EŞ

EK

KÜ

R E

DE

RİM

TH

AN

K Y

OU