rapid source parameter determination and earthquake source process in indonesia region iman suardi...
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RAPID SOURCE PARAMETER DETERMINATION AND EARTHQUAKE
SOURCE PROCESS IN INDONESIA REGION
Iman Suardi Seismology
Course Indonesia
Final Presentation of Master Report August 28, 2007
International Institute of Seismology and Earthquake Engineering, Building Research Institute, Tsukuba,
Japan, 2006-2007
Supervisor:DR. Akio KATSUMATA (MRI-JMA)
Prof. Yuji YAGI (Tsukuba University)
INTRODUCTION
DATA
THEORY AND METHODOLOGY
RESULTS AND DISCUSSIONS
CONCLUSION
RECOMMENDATION
CONTENTS
CONTENTS
Indonesia Earthquake Information and Tsunami Warning Center (InaTWS end 2008)
INTRODUCTION
INTRODUCTION
Tectonic Setting of Indonesia
Tectonic Setting of Indonesia
Propose a new rapid method to determine earthquake magnitude
release a new BMG magnitude tsunami early warning,
Determine focal mechanism and seismic moment,
Determine moment magnitude,
Compare moment magnitude with the above magnitude.
Purpose of This StudyPurpose of This Study
Distribution Of The New Accelerometer Network Of BMG
data range from 4 March 2007 – 25 April 2007
DATADATA
Raw Data from Accelerometer TSA100S from Nanometrics Inc.
(continuous waveform data).
Convert to XFiles format
Convert to Seed format
Convert to SAC (by using rdseed4.6)
using software Data Playback prepared by Nanometrics Inc.
Continuous waveform data from 4 March – 25 April 2007
Calculated Magnitude of BMGCalculated Magnitude of BMG
Moment Tensor InversionMoment Tensor Inversion
Event data collection from Global CMTRetrieve waveform data from internet (IRIS network / FDSN-GSN
stations)Remove instrument responses
Data PreparationData Preparation
The performance of waveform before converting and after converting into displacement record for event5 (2007/03/17, M6.2, depth 40.7 km, 1.30N; 126.37E).
before
after
Earthquake event list from the Global CMT (4 March 2007 – 25 April 2007).
Data Retrieval from IRIS-DMC
No. Eventyyyymmd
dLocation
MW Global
CMT
Depth
(km)
1
2
3
4
5
6
7
8
event1
event2
event3
event4
event5
event6
event7
event8
20070309
20070313
20070315
20070315
20070317
20070326
20070331
20070407
-6.34S, 130.23E
-8.08S, 117.94E
-0.73S, 127.60E
4.19N, 127.04E
1.30N, 126.37E
0.98N, 126.05E
1.55N, 122.63E
2.72N, 95.47E
5.6
5.6
5.4
5.2
6.2
5.5
5.6
6.1
149.3
24.1
12.0
18.5
40.7
29.0
21.9
12.0
IRIS-DMC stations
Magnitudes ScalesMagnitudes Scales
Body Wave Magnitude, mb
mb = Log10(A/T) + q(∆,h), where: A(µm), Amplitude (SP); T(s), Period;
∆ (deg), Epicentral Distance; h(km), Focal Depth.
Based on amplitudes of P waves (T~1 sec) not appropriate for large earthquake.
Surface Wave Magnitude, Ms, Gutenberg (1945)
Ms = Log10(A/T) + 1.66Log10∆ + 3.3, where: A(µm), Amplitude (LP); T(s), Period; ∆ (deg), Epicentral Distance.
Based on amplitudes of surface waves (T~20 sec) easy to determine, underestimate size for great earthquakes.
Moment Magnitude, Mw, Kanamori (1977)
Mw = (Log10Mo – 9.1)/1.5, Mo (Nm) = µDS : Seismic Moment
where: µ rigidity; D Displacement; S Fault Area.
Based on moment tensor solutions such as USGS MT solutions and Global CMT
solution No saturation, Difficult to determine.
Broadband Moment Magnitude, Tsuboi et al. (1995).
Mwp = Mw + 0.2
Body Wave Magnitude, mb
mb = Log10(A/T) + q(∆,h), where: A(µm), Amplitude (SP); T(s), Period;
∆ (deg), Epicentral Distance; h(km), Focal Depth.
Based on amplitudes of P waves (T~1 sec) not appropriate for large earthquake.
Surface Wave Magnitude, Ms, Gutenberg (1945)
Ms = Log10(A/T) + 1.66Log10∆ + 3.3, where: A(µm), Amplitude (LP); T(s), Period; ∆ (deg), Epicentral Distance.
Based on amplitudes of surface waves (T~20 sec) easy to determine, underestimate size for great earthquakes.
Moment Magnitude, Mw, Kanamori (1977)
Mw = (Log10Mo – 9.1)/1.5, Mo (Nm) = µDS : Seismic Moment
where: µ rigidity; D Displacement; S Fault Area.
Based on moment tensor solutions such as USGS MT solutions and Global CMT
solution No saturation, Difficult to determine.
Broadband Moment Magnitude, Tsuboi et al. (1995).
Mwp = Mw + 0.2
THEORY AND METHODOLOGYTHEORY AND METHODOLOGY
Magnitude JMA, MJMA using accelerometer
DDDD CHAM ),(log
For distance within 2000 km
, Tsuboi’s formula (1954).
Shallow earthquake < 60 km.
, Katsumata’s formula (2004).
R > 30 km, ∆ < 700 km , Funasaki et al.
(2004) R > 5 km, ∆ < 700 km
where: AD is the maximum amplitude (µm), AZ isvertical component of velocity , , Attenuation Function depends on epicentral distance ∆ and on the focal depth, H, CV depends on instrumental conditions of seismographs.
),( HD
VVZV CHAM ),(log)85.0/1(
83.0log73.1log 1010 DAM
Continued …Continued …
DDWDD RMA 1010 loglog
Empirical Formula of Richter’s Magnitude
Empirical Formula
A New Magnitude for BMG
Find coefficients Least Square Method
Least Square Method find coefficient a1, a2, and a3
j i
jijij bRaA 22 )log(log
j i
wijij MaaRaA 2132 )log(log
minimum
minimum
event station
unknown
constant
constant
unknown
WMaa 13
unknown
Unit impulsive slip
Propagate wave
Observed station
Green’s functionGreen’s Function
The response function, effect of propagation, with unit impulsive slip
and / or force.
Determination of Source Parameter:
faulting type Focal mechanism,
earthquake size Seismic Moment, Moment
Magnitude.
Moment Tensor InversionMoment Tensor Inversion
jcccjqq
qj etTzyxtGmtd
)(),,,()(5
1
jjcccjj zyxtT emGd ),),(( ,
5
4
3
2
1
11
222
111
1
2
1
,
)( )(
)( )( )(
)( )( )(
,
)(
)(
)(
51
521
21
m
m
m
m
m
tGtG
tGtGtG
tGtGtG
td
td
td
mns
mns
mud
mud
mud
mud
mud
mud
ns
ud
uds
mGd
Empirical Equation
321 loglog aRaRAMa
321 loglog aRaAMa
3617185.000160585.0loglog RRMA
88362.1log15048.2log RMA
Type2:
Type1:
RESULTS AND DISCUSSIONSRESULTS AND DISCUSSIONS
The Magnitude Determination of BMG
The Magnitude Determination of BMG
321 loglog aRaAMa Type2:
Tsuboi’s formula
83.0log73.1log MA
A Calculated Magnitude of BMG
88362.1log15048.2log RMA
88362.1log15048.2log 1010 RAM DBMG
or
Graph of Comparison of maximum amplitudes of three type of magnitude calculation plotted against
epicentral distances for each events.
Graph of comparison between the moment magnitude from Global CMT and
the calculated magnitude of BMG (type2).
Difference between the calculated magnitude of
BMG and the moment magnitude of Global CMT
plotted against the moment magnitude of Global CMT.
Difference between the calculated magnitude of BMG
and the moment magnitude from Global CMT plotted
against the depth of earthquakes.
Graph of difference between observed maximum amplitudes and estimated ones plotted against
hypocentral distances for all the events.
(a)
(b)
The results of moment tensor inversion of 5 earthquake events. (a) Assumed
source time function and focal mechanism. (b) Theoretical waveforms
(red curves) from a point source and observed waveforms (black curves).
Moment Tensor Inversion
Moment Tensor Inversion
Graph of comparison between the moment magnitude from Global CMT and the moment
magnitude obtained from moment tensor inversion.
Graph of comparison between the magnitude determination of BMG and the moment magnitude obtained from moment tensor inversion.
Comparison of focal mechanism from Global CMT (blue color) and from moment tensor
inversion (red color). Green stars denote epicenters; red triangles denote
accelerometer station used for calculating the magnitude of BMG.
The magnitude determination of BMG:
The consistency with the other magnitude determination, the magnitude determination of BMG is still sufficient and reliable for shallow earthquakes less than 150 kilometers and the hypocentral distance less than 1,000 kilometers,
The seismic moments and moment magnitude estimated by moment tensor inversion are generally consistent with those of Global CMT,
The magnitude determination of BMG is systematically consistent with the results from moment tensor inversion;
For the rapid earthquakes indicated by short source duration time, the magnitude determination of BMG will become overestimated, The slow earthquakes indicated by long source duration time, the magnitude determination of BMG will become underestimated.
88362.1log15048.2log 1010 RAM DBMG
CONCLUSIONCONCLUSION
RECOMMENDATIONRECOMMENDATION
The formula of the magnitude determination of BMG could be improved after seismic records are accumulated in BMG. Collecting and storing data should be well managed. The long time collected data is of an urgent necessity in order to make reliable coefficients of this formula.
The dense distribution of accelerometer station should be realized in order to obtain high quality of data.
Intensive study of magnitude determination of tsunami earthquakes will give advantage to improve the reliability of this formula.