2012/07/26 10:24:58 37.98 125.45 10.0 3.4 Korea
USGS Felt map for this earthquake
USGS/SLU Moment Tensor Solution
ENS 2012/07/26 10:24:58:0 0.00 37.98 125.4 10.0 Korea
Stations used:
KS.BAR KS.BUS KS.BUS2 KS.CHC KS.CHJ KS.DAG2 KS.GAHB KS.HWCB
KS.JEO KS.KOHB KS.KWJ KS.SEO KS.SEO2 KS.SES KS.YNCB
Filtering commands used:
hp c 0.02 n 3
lp c 0.12 n 3
Best Fitting Double Couple
Mo = 1.43e+21 dyne-cm
Mw = 3.37
Z = 13 km
Plane Strike Dip Rake
NP1 222 77 149
NP2 320 60 15
Principal Axes:
Axis Value Plunge Azimuth
T 1.43e+21 31 177
N 0.00e+00 57 22
P -1.43e+21 11 274
Moment Tensor: (dyne-cm)
Component Value
Mxx 1.04e+21
Mxy 4.99e+19
Mxz -6.48e+20
Myy -1.37e+21
Myz 3.02e+20
Mzz 3.20e+20
##############
######################
---#########################
----------################----
---------------##########---------
------------------######------------
----------------------#---------------
----------------------##----------------
--------------------######--------------
- ---------------#########--------------
- P -------------#############------------
- ------------###############-----------
--------------##################----------
------------####################--------
-----------#####################--------
--------########################------
------#########################-----
----############ ###########----
--############ T ############-
############# ###########-
######################
##############
Global CMT Convention Moment Tensor:
R T P
3.20e+20 -6.48e+20 -3.02e+20
-6.48e+20 1.04e+21 -4.99e+19
-3.02e+20 -4.99e+19 -1.37e+21
Details of the solution is found at
http://www.eas.slu.edu/Earthquake_Center/MECH.NA/20120726102458/index.html
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STK = 320
DIP = 60
RAKE = 15
MW = 3.37
HS = 13.0
The waveform inversion is preferred.
The following compares this source inversion to others
USGS/SLU Moment Tensor Solution
ENS 2012/07/26 10:24:58:0 0.00 37.98 125.4 10.0 Korea
Stations used:
KS.BAR KS.BUS KS.BUS2 KS.CHC KS.CHJ KS.DAG2 KS.GAHB KS.HWCB
KS.JEO KS.KOHB KS.KWJ KS.SEO KS.SEO2 KS.SES KS.YNCB
Filtering commands used:
hp c 0.02 n 3
lp c 0.12 n 3
Best Fitting Double Couple
Mo = 1.43e+21 dyne-cm
Mw = 3.37
Z = 13 km
Plane Strike Dip Rake
NP1 222 77 149
NP2 320 60 15
Principal Axes:
Axis Value Plunge Azimuth
T 1.43e+21 31 177
N 0.00e+00 57 22
P -1.43e+21 11 274
Moment Tensor: (dyne-cm)
Component Value
Mxx 1.04e+21
Mxy 4.99e+19
Mxz -6.48e+20
Myy -1.37e+21
Myz 3.02e+20
Mzz 3.20e+20
##############
######################
---#########################
----------################----
---------------##########---------
------------------######------------
----------------------#---------------
----------------------##----------------
--------------------######--------------
- ---------------#########--------------
- P -------------#############------------
- ------------###############-----------
--------------##################----------
------------####################--------
-----------#####################--------
--------########################------
------#########################-----
----############ ###########----
--############ T ############-
############# ###########-
######################
##############
Global CMT Convention Moment Tensor:
R T P
3.20e+20 -6.48e+20 -3.02e+20
-6.48e+20 1.04e+21 -4.99e+19
-3.02e+20 -4.99e+19 -1.37e+21
Details of the solution is found at
http://www.eas.slu.edu/Earthquake_Center/MECH.NA/20120726102458/index.html
|
The focal mechanism was determined using broadband seismic waveforms. The location of the event and the and stations used for the waveform inversion are shown in the next figure.
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The program wvfgrd96 was used with good traces observed at short distance to determine the focal mechanism, depth and seismic moment. This technique requires a high quality signal and well determined velocity model for the Green functions. To the extent that these are the quality data, this type of mechanism should be preferred over the radiation pattern technique which requires the separate step of defining the pressure and tension quadrants and the correct strike.
The observed and predicted traces are filtered using the following gsac commands:
hp c 0.02 n 3 lp c 0.12 n 3The results of this grid search from 0.5 to 19 km depth are as follow:
DEPTH STK DIP RAKE MW FIT
WVFGRD96 0.5 90 40 -95 3.25 0.3730
WVFGRD96 1.0 210 50 -45 3.14 0.3849
WVFGRD96 2.0 140 70 10 3.16 0.3690
WVFGRD96 3.0 305 50 -30 3.21 0.3843
WVFGRD96 4.0 305 50 -30 3.22 0.4184
WVFGRD96 5.0 310 55 -20 3.23 0.4520
WVFGRD96 6.0 310 60 -20 3.25 0.4820
WVFGRD96 7.0 310 60 -15 3.26 0.5099
WVFGRD96 8.0 315 60 -5 3.29 0.5332
WVFGRD96 9.0 315 60 0 3.30 0.5534
WVFGRD96 10.0 315 60 0 3.32 0.5693
WVFGRD96 11.0 315 60 0 3.33 0.5789
WVFGRD96 12.0 320 60 15 3.36 0.5841
WVFGRD96 13.0 320 60 15 3.37 0.5868
WVFGRD96 14.0 320 60 15 3.38 0.5843
WVFGRD96 15.0 320 65 15 3.40 0.5789
WVFGRD96 16.0 320 65 15 3.41 0.5720
WVFGRD96 17.0 320 65 15 3.43 0.5628
WVFGRD96 18.0 320 65 15 3.44 0.5508
WVFGRD96 19.0 320 65 20 3.44 0.5373
WVFGRD96 20.0 325 65 25 3.46 0.5245
WVFGRD96 21.0 325 65 30 3.47 0.5109
WVFGRD96 22.0 325 65 35 3.48 0.4963
WVFGRD96 23.0 325 65 35 3.49 0.4820
WVFGRD96 24.0 325 65 40 3.49 0.4659
WVFGRD96 25.0 325 65 45 3.51 0.4527
WVFGRD96 0.0 0 0****** 0.00-2.0000
WVFGRD96 0.0 0 0****** 0.00-2.0000
WVFGRD96 0.0 0 0****** 0.00-2.0000
WVFGRD96 0.0 0 0****** 0.00-2.0000
The best solution is
WVFGRD96 13.0 320 60 15 3.37 0.5868
The mechanism corresponding to the best fit is
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The best fit as a function of depth is given in the following figure:
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The comparison of the observed and predicted waveforms is given in the next figure. The red traces are the observed and the blue are the predicted. Each observed-predicted component is plotted to the same scale and peak amplitudes are indicated by the numbers to the left of each trace. A pair of numbers is given in black at the right of each predicted traces. The upper number it the time shift required for maximum correlation between the observed and predicted traces. This time shift is required because the synthetics are not computed at exactly the same distance as the observed and because the velocity model used in the predictions may not be perfect. A positive time shift indicates that the prediction is too fast and should be delayed to match the observed trace (shift to the right in this figure). A negative value indicates that the prediction is too slow. The lower number gives the percentage of variance reduction to characterize the individual goodness of fit (100% indicates a perfect fit).
The bandpass filter used in the processing and for the display was
hp c 0.02 n 3 lp c 0.12 n 3
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| Focal mechanism sensitivity at the preferred depth. The red color indicates a very good fit to thewavefroms. Each solution is plotted as a vector at a given value of strike and dip with the angle of the vector representing the rake angle, measured, with respect to the upward vertical (N) in the figure. |
A check on the assumed source location is possible by looking at the time shifts between the observed and predicted traces. The time shifts for waveform matching arise for several reasons:
Time_shift = A + B cos Azimuth + C Sin Azimuth
The time shifts for this inversion lead to the next figure:
The derived shift in origin time and epicentral coordinates are given at the bottom of the figure.
Thanks also to the many seismic network operators whose dedication make this effort possible: University of Alaska, University of Washington, Oregon State University, University of Utah, Montana Bureas of Mines, UC Berkely, Caltech, UC San Diego, Saint Louis University, University of Memphis, Lamont Doherty Earth Observatory, the IRIS stations and the Transportable Array of EarthScope.
The t6.invSNU.CUVEL model was used for the waveform synthetic seismograms and for the surface wave eigenfunctions and dispersion is as follows:
MODEL.01
Model after 30 iterations
ISOTROPIC
KGS
SPHERICAL EARTH
1-D
CONSTANT VELOCITY
LINE08
LINE09
LINE10
LINE11
H(KM) VP(KM/S) VS(KM/S) RHO(GM/CC) QP QS ETAP ETAS FREFP FREFS
1.0000 5.3800 3.0009 2.5772 0.118E-02 0.167E-02 0.00 0.00 1.00 1.00
1.0000 5.8057 3.2383 2.6606 0.118E-02 0.167E-02 0.00 0.00 1.00 1.00
1.0000 6.1732 3.4433 2.7513 0.118E-02 0.167E-02 0.00 0.00 1.00 1.00
3.0000 6.2872 3.5067 2.7862 0.118E-02 0.167E-02 0.00 0.00 1.00 1.00
5.0000 6.3245 3.5281 2.7970 0.118E-02 0.167E-02 0.00 0.00 1.00 1.00
5.0000 6.4165 3.5788 2.8248 0.118E-02 0.167E-02 0.00 0.00 1.00 1.00
4.0000 6.5576 3.6576 2.8653 0.118E-02 0.167E-02 0.00 0.00 1.00 1.00
5.0000 6.6402 3.7038 2.8865 0.118E-02 0.167E-02 0.00 0.00 1.00 1.00
2.5000 6.6540 3.7115 2.8897 0.118E-02 0.167E-02 0.00 0.00 1.00 1.00
2.5000 7.0960 3.9579 3.0111 0.118E-02 0.167E-02 0.00 0.00 1.00 1.00
2.5000 7.9155 4.4148 3.2804 0.118E-02 0.167E-02 0.00 0.00 1.00 1.00
2.5000 7.8925 4.4019 3.2735 0.118E-02 0.167E-02 0.00 0.00 1.00 1.00
5.0000 7.8665 4.3876 3.2643 0.118E-02 0.167E-02 0.00 0.00 1.00 1.00
5.0000 7.5675 4.2211 3.1625 0.118E-02 0.167E-02 0.00 0.00 1.00 1.00
5.0000 7.7550 4.3252 3.2262 0.118E-02 0.167E-02 0.00 0.00 1.00 1.00
5.0000 7.7602 4.3280 3.2282 0.118E-02 0.167E-02 0.00 0.00 1.00 1.00
5.0000 7.7958 4.3487 3.2398 0.118E-02 0.167E-02 0.00 0.00 1.00 1.00
5.0000 7.7415 4.3195 3.2217 0.118E-02 0.167E-02 0.00 0.00 1.00 1.00
5.0000 7.6497 4.2688 3.1915 0.118E-02 0.167E-02 0.00 0.00 1.00 1.00
5.0000 7.6408 4.2653 3.1889 0.118E-02 0.167E-02 0.00 0.00 1.00 1.00
5.0000 7.6666 4.2716 3.1976 0.118E-02 0.167E-02 0.00 0.00 1.00 1.00
5.0000 7.6699 4.2830 3.1986 0.118E-02 0.167E-02 0.00 0.00 1.00 1.00
5.0000 7.6780 4.2885 3.2014 0.118E-02 0.167E-02 0.00 0.00 1.00 1.00
5.0000 7.6816 4.2896 3.2028 0.118E-02 0.167E-02 0.00 0.00 1.00 1.00
5.0000 7.6946 4.2996 3.2072 0.118E-02 0.167E-02 0.00 0.00 1.00 1.00
10.0000 7.7349 4.3197 3.2208 0.118E-02 0.167E-02 0.00 0.00 1.00 1.00
10.0000 7.7791 4.3484 3.2355 0.118E-02 0.167E-02 0.00 0.00 1.00 1.00
10.0000 7.8331 4.3722 3.2536 0.862E-02 0.131E-01 0.00 0.00 1.00 1.00
10.0000 7.8824 4.3863 3.2703 0.862E-02 0.131E-01 0.00 0.00 1.00 1.00
10.0000 7.9360 4.4024 3.2883 0.855E-02 0.131E-01 0.00 0.00 1.00 1.00
10.0000 7.9967 4.4237 3.3088 0.847E-02 0.131E-01 0.00 0.00 1.00 1.00
10.0000 8.0529 4.4423 3.3289 0.847E-02 0.131E-01 0.00 0.00 1.00 1.00
10.0000 8.1110 4.4603 3.3496 0.833E-02 0.130E-01 0.00 0.00 1.00 1.00
10.0000 8.1762 4.4832 3.3728 0.826E-02 0.129E-01 0.00 0.00 1.00 1.00
10.0000 8.2410 4.5054 3.3959 0.813E-02 0.128E-01 0.00 0.00 1.00 1.00
10.0000 8.3022 4.5257 3.4176 0.806E-02 0.126E-01 0.00 0.00 1.00 1.00
10.0000 8.3635 4.5514 3.4395 0.474E-02 0.746E-02 0.00 0.00 1.00 1.00
10.0000 8.4257 4.5839 3.4617 0.472E-02 0.741E-02 0.00 0.00 1.00 1.00
10.0000 8.4845 4.6145 3.4827 0.469E-02 0.741E-02 0.00 0.00 1.00 1.00
10.0000 8.5403 4.6434 3.5020 0.467E-02 0.735E-02 0.00 0.00 1.00 1.00
10.0000 8.5934 4.6708 3.5199 0.465E-02 0.735E-02 0.00 0.00 1.00 1.00
10.0000 8.6436 4.6959 3.5369 0.463E-02 0.730E-02 0.00 0.00 1.00 1.00
10.0000 8.6912 4.7194 3.5530 0.461E-02 0.730E-02 0.00 0.00 1.00 1.00
10.0000 8.7365 4.7413 3.5684 0.459E-02 0.725E-02 0.00 0.00 1.00 1.00
10.0000 8.7797 4.7622 3.5831 0.455E-02 0.725E-02 0.00 0.00 1.00 1.00
10.0000 8.8199 4.7819 3.5967 0.452E-02 0.719E-02 0.00 0.00 1.00 1.00
10.0000 8.8587 4.8001 3.6099 0.450E-02 0.714E-02 0.00 0.00 1.00 1.00
10.0000 8.8958 4.8177 3.6226 0.448E-02 0.714E-02 0.00 0.00 1.00 1.00
10.0000 8.9314 4.8346 3.6347 0.446E-02 0.709E-02 0.00 0.00 1.00 1.00
10.0000 8.9647 4.8500 3.6461 0.442E-02 0.704E-02 0.00 0.00 1.00 1.00
10.0000 8.9962 4.8651 3.6569 0.441E-02 0.704E-02 0.00 0.00 1.00 1.00
10.0000 9.0263 4.8783 3.6685 0.439E-02 0.699E-02 0.00 0.00 1.00 1.00
10.0000 9.0547 4.8915 3.6800 0.435E-02 0.694E-02 0.00 0.00 1.00 1.00
10.0000 9.0822 4.9041 3.6911 0.433E-02 0.690E-02 0.00 0.00 1.00 1.00
10.0000 9.1091 4.9164 3.7020 0.431E-02 0.690E-02 0.00 0.00 1.00 1.00
10.0000 9.1346 4.9280 3.7123 0.427E-02 0.685E-02 0.00 0.00 1.00 1.00
10.0000 9.4876 5.1513 3.8537 0.388E-02 0.613E-02 0.00 0.00 1.00 1.00
10.0000 9.5095 5.1663 3.8624 0.388E-02 0.613E-02 0.00 0.00 1.00 1.00
10.0000 9.5299 5.1806 3.8703 0.386E-02 0.610E-02 0.00 0.00 1.00 1.00
10.0000 9.5507 5.1944 3.8784 0.386E-02 0.610E-02 0.00 0.00 1.00 1.00
10.0000 9.5706 5.2080 3.8861 0.385E-02 0.606E-02 0.00 0.00 1.00 1.00
10.0000 9.5900 5.2214 3.8937 0.385E-02 0.606E-02 0.00 0.00 1.00 1.00
10.0000 9.6090 5.2347 3.9011 0.383E-02 0.606E-02 0.00 0.00 1.00 1.00
10.0000 9.6272 5.2480 3.9081 0.383E-02 0.602E-02 0.00 0.00 1.00 1.00
10.0000 9.6458 5.2604 3.9154 0.383E-02 0.602E-02 0.00 0.00 1.00 1.00
10.0000 9.6794 5.2816 3.9282 0.382E-02 0.599E-02 0.00 0.00 1.00 1.00
10.0000 9.7130 5.3029 3.9409 0.382E-02 0.599E-02 0.00 0.00 1.00 1.00
10.0000 9.7466 5.3242 3.9537 0.380E-02 0.599E-02 0.00 0.00 1.00 1.00
10.0000 9.7799 5.3454 3.9664 0.380E-02 0.595E-02 0.00 0.00 1.00 1.00
10.0000 9.8137 5.3669 3.9792 0.380E-02 0.595E-02 0.00 0.00 1.00 1.00
10.0000 9.8473 5.3883 3.9920 0.379E-02 0.592E-02 0.00 0.00 1.00 1.00
10.0000 9.8808 5.4094 4.0047 0.379E-02 0.592E-02 0.00 0.00 1.00 1.00
0.0000 9.9144 5.4306 4.0175 0.377E-02 0.592E-02 0.00 0.00 1.00 1.00
Here we tabulate the reasons for not using certain digital data sets
The following stations did not have a valid response files:
DATE=Wed Aug 15 15:57:02 CDT 2012