2014/03/31 19:48:35 36.95 124.50 10.0 5.1 Korea
USGS Felt map for this earthquake
USGS/SLU Moment Tensor Solution
ENS 2014/03/31 19:48:35:0 36.95 124.50 10.0 5.1 Korea
Stations used:
KS.BAR KS.BUS KS.BUS2 KS.CHJ KS.DACB KS.DAG2 KS.DGY2
KS.GAHB KS.HWCB KS.JJU KS.KOHB KS.KWJ KS.SEHB KS.SEO
KS.SEO2
Filtering commands used:
hp c 0.02 n 3
lp c 0.10 n 3
Best Fitting Double Couple
Mo = 1.62e+23 dyne-cm
Mw = 4.74
Z = 12 km
Plane Strike Dip Rake
NP1 115 60 -45
NP2 232 52 -141
Principal Axes:
Axis Value Plunge Azimuth
T 1.62e+23 5 175
N 0.00e+00 38 268
P -1.62e+23 52 79
Moment Tensor: (dyne-cm)
Component Value
Mxx 1.58e+23
Mxy -2.58e+22
Mxz -2.77e+22
Myy -5.83e+22
Myz -7.62e+22
Mzz -9.93e+22
##############
######################
############################
##############################
###################---------------
################--------------------
##############------------------------
--###########---------------------------
---########-----------------------------
-----#####------------------- ----------
-------##-------------------- P ----------
--------#-------------------- ----------
-------####-------------------------------
-----########---------------------------
----############------------------------
---################-------------------
--#########################----#####
-#################################
##############################
############################
########### ########
####### T ####
Global CMT Convention Moment Tensor:
R T P
-9.93e+22 -2.77e+22 7.62e+22
-2.77e+22 1.58e+23 2.58e+22
7.62e+22 2.58e+22 -5.83e+22
Details of the solution is found at
http://www.eas.slu.edu/eqc/eqc_mt/MECH.NA/20140331194835/index.html
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STK = 115
DIP = 60
RAKE = -45
MW = 4.74
HS = 12.0
The waveform inversion is preferred.
The following compares this source inversion to others
USGS/SLU Moment Tensor Solution
ENS 2014/03/31 19:48:35:0 36.95 124.50 10.0 5.1 Korea
Stations used:
KS.BAR KS.BUS KS.BUS2 KS.CHJ KS.DACB KS.DAG2 KS.DGY2
KS.GAHB KS.HWCB KS.JJU KS.KOHB KS.KWJ KS.SEHB KS.SEO
KS.SEO2
Filtering commands used:
hp c 0.02 n 3
lp c 0.10 n 3
Best Fitting Double Couple
Mo = 1.62e+23 dyne-cm
Mw = 4.74
Z = 12 km
Plane Strike Dip Rake
NP1 115 60 -45
NP2 232 52 -141
Principal Axes:
Axis Value Plunge Azimuth
T 1.62e+23 5 175
N 0.00e+00 38 268
P -1.62e+23 52 79
Moment Tensor: (dyne-cm)
Component Value
Mxx 1.58e+23
Mxy -2.58e+22
Mxz -2.77e+22
Myy -5.83e+22
Myz -7.62e+22
Mzz -9.93e+22
##############
######################
############################
##############################
###################---------------
################--------------------
##############------------------------
--###########---------------------------
---########-----------------------------
-----#####------------------- ----------
-------##-------------------- P ----------
--------#-------------------- ----------
-------####-------------------------------
-----########---------------------------
----############------------------------
---################-------------------
--#########################----#####
-#################################
##############################
############################
########### ########
####### T ####
Global CMT Convention Moment Tensor:
R T P
-9.93e+22 -2.77e+22 7.62e+22
-2.77e+22 1.58e+23 2.58e+22
7.62e+22 2.58e+22 -5.83e+22
Details of the solution is found at
http://www.eas.slu.edu/eqc/eqc_mt/MECH.NA/20140331194835/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 0.10 n 3The results of this grid search from 0.5 to 19 km depth are as follow:
DEPTH STK DIP RAKE MW FIT
WVFGRD96 0.5 300 50 80 4.51 0.5801
WVFGRD96 1.0 310 45 80 4.57 0.5731
WVFGRD96 2.0 120 70 65 4.64 0.5450
WVFGRD96 3.0 135 65 60 4.67 0.5606
WVFGRD96 4.0 120 70 60 4.64 0.5631
WVFGRD96 5.0 120 85 -50 4.62 0.5872
WVFGRD96 6.0 110 65 -55 4.67 0.6554
WVFGRD96 7.0 100 55 -65 4.72 0.7232
WVFGRD96 8.0 105 55 -60 4.72 0.7733
WVFGRD96 9.0 105 55 -55 4.72 0.8038
WVFGRD96 10.0 110 55 -50 4.73 0.8220
WVFGRD96 11.0 110 55 -50 4.74 0.8308
WVFGRD96 12.0 115 60 -45 4.74 0.8333
WVFGRD96 13.0 115 60 -45 4.75 0.8293
WVFGRD96 14.0 115 60 -45 4.75 0.8196
WVFGRD96 15.0 115 60 -45 4.76 0.8065
WVFGRD96 16.0 115 60 -45 4.77 0.7902
WVFGRD96 17.0 115 55 -40 4.79 0.7740
WVFGRD96 18.0 120 60 -35 4.81 0.7568
WVFGRD96 19.0 120 55 -35 4.82 0.7388
WVFGRD96 20.0 120 55 -35 4.83 0.7196
WVFGRD96 21.0 120 55 -35 4.84 0.7010
WVFGRD96 22.0 120 55 -35 4.85 0.6819
WVFGRD96 23.0 120 55 -30 4.86 0.6613
WVFGRD96 24.0 120 55 -30 4.87 0.6402
WVFGRD96 25.0 120 55 -30 4.88 0.6188
The best solution is
WVFGRD96 12.0 115 60 -45 4.74 0.8333
The mechanism correspond 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 0.10 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.
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.
|
|
|
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 0.04 n 3 lp c 0.20 n 3The results of this grid search from 0.5 to 19 km depth are as follow:
DEPTH STK DIP RAKE MW FIT
WVFGRD96 0.5 135 45 90 4.43 0.4011
WVFGRD96 1.0 140 45 90 4.51 0.3969
WVFGRD96 2.0 140 70 45 4.46 0.3026
WVFGRD96 3.0 105 85 55 4.45 0.3259
WVFGRD96 4.0 110 80 55 4.48 0.3630
WVFGRD96 5.0 110 75 60 4.50 0.3941
WVFGRD96 6.0 275 75 -60 4.53 0.4206
WVFGRD96 7.0 110 60 -55 4.59 0.4679
WVFGRD96 8.0 110 60 -60 4.63 0.5067
WVFGRD96 9.0 115 65 -55 4.65 0.5377
WVFGRD96 10.0 115 65 -55 4.67 0.5599
WVFGRD96 11.0 115 65 -55 4.69 0.5709
WVFGRD96 12.0 115 65 -55 4.72 0.5750
WVFGRD96 13.0 110 60 -60 4.74 0.5680
WVFGRD96 14.0 110 60 -60 4.76 0.5506
WVFGRD96 15.0 110 60 -60 4.77 0.5267
WVFGRD96 16.0 110 60 -60 4.77 0.4965
WVFGRD96 17.0 110 60 -60 4.79 0.4611
WVFGRD96 18.0 105 35 -55 4.80 0.4343
WVFGRD96 19.0 105 35 -55 4.81 0.4165
WVFGRD96 20.0 95 30 -65 4.82 0.4001
WVFGRD96 21.0 95 30 -65 4.83 0.3842
WVFGRD96 22.0 90 30 -75 4.85 0.3693
WVFGRD96 23.0 85 30 -80 4.86 0.3548
WVFGRD96 24.0 90 30 -75 4.87 0.3410
WVFGRD96 25.0 90 30 -75 4.87 0.3280
The best solution is
WVFGRD96 12.0 115 65 -55 4.72 0.5750
The mechanism correspond to the best fit is
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|
|
The best fit as a function of depth is given in the following figure:
|
|
|
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 0.04 n 3 lp c 0.20 n 3
|
|
|
|
| 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. |
Thanks also to the many seismic network operators whose dedication make this effort possible: University of Nevada Reno, 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 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: