2014/03/22 12:59:58 -19.770 -70.936 15.2 6.2 Chile
USGS Felt map for this earthquake
USGS/SLU Moment Tensor Solution
ENS 2014/03/22 12:59:58:0 -19.77 -70.94 15.2 6.2 Chile
Stations used:
C.GO01 CX.PATCX CX.PB01 CX.PB04 CX.PB07 CX.PB09 CX.PB10
CX.PB11 CX.PB12 CX.PB14 CX.PB15 CX.PB16 CX.PSGCX GT.LPAZ
IU.LVC
Filtering commands used:
cut a -30 a 180
rtr
taper w 0.1
hp c 0.02 n 3
lp c 0.10 n 3
Best Fitting Double Couple
Mo = 1.66e+25 dyne-cm
Mw = 6.08
Z = 20 km
Plane Strike Dip Rake
NP1 160 75 91
NP2 335 15 85
Principal Axes:
Axis Value Plunge Azimuth
T 1.66e+25 60 72
N 0.00e+00 1 340
P -1.66e+25 30 249
Moment Tensor: (dyne-cm)
Component Value
Mxx -1.19e+24
Mxy -2.93e+24
Mxz 4.78e+24
Myy -7.08e+24
Myz 1.36e+25
Mzz 8.27e+24
-#######------
----#############-----
-------#################----
--------###################---
----------####################----
-----------######################---
-------------######################---
--------------#######################---
---------------########### ########---
----------------########### T #########---
-----------------########## #########---
-----------------######################---
------ ---------#####################---
----- P ----------####################--
----- ----------####################--
------------------##################--
------------------################--
------------------##############--
-----------------############-
------------------#########-
----------------######
--------------
Global CMT Convention Moment Tensor:
R T P
8.27e+24 4.78e+24 -1.36e+25
4.78e+24 -1.19e+24 2.93e+24
-1.36e+25 2.93e+24 -7.08e+24
Details of the solution is found at
http://www.eas.slu.edu/eqc/eqc_mt/MECH.NA/20140322125958/index.html
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STK = 335
DIP = 15
RAKE = 85
MW = 6.08
HS = 20.0
The NDK file is 20140322125958.ndk The waveform inversion is preferred.
The following compares this source inversion to others
USGS/SLU Moment Tensor Solution
ENS 2014/03/22 12:59:58:0 -19.77 -70.94 15.2 6.2 Chile
Stations used:
C.GO01 CX.PATCX CX.PB01 CX.PB04 CX.PB07 CX.PB09 CX.PB10
CX.PB11 CX.PB12 CX.PB14 CX.PB15 CX.PB16 CX.PSGCX GT.LPAZ
IU.LVC
Filtering commands used:
cut a -30 a 180
rtr
taper w 0.1
hp c 0.02 n 3
lp c 0.10 n 3
Best Fitting Double Couple
Mo = 1.66e+25 dyne-cm
Mw = 6.08
Z = 20 km
Plane Strike Dip Rake
NP1 160 75 91
NP2 335 15 85
Principal Axes:
Axis Value Plunge Azimuth
T 1.66e+25 60 72
N 0.00e+00 1 340
P -1.66e+25 30 249
Moment Tensor: (dyne-cm)
Component Value
Mxx -1.19e+24
Mxy -2.93e+24
Mxz 4.78e+24
Myy -7.08e+24
Myz 1.36e+25
Mzz 8.27e+24
-#######------
----#############-----
-------#################----
--------###################---
----------####################----
-----------######################---
-------------######################---
--------------#######################---
---------------########### ########---
----------------########### T #########---
-----------------########## #########---
-----------------######################---
------ ---------#####################---
----- P ----------####################--
----- ----------####################--
------------------##################--
------------------################--
------------------##############--
-----------------############-
------------------#########-
----------------######
--------------
Global CMT Convention Moment Tensor:
R T P
8.27e+24 4.78e+24 -1.36e+25
4.78e+24 -1.19e+24 2.93e+24
-1.36e+25 2.93e+24 -7.08e+24
Details of the solution is found at
http://www.eas.slu.edu/eqc/eqc_mt/MECH.NA/20140322125958/index.html
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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:
cut a -30 a 180 rtr taper w 0.1 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 2.0 170 40 90 5.71 0.3281
WVFGRD96 4.0 220 10 -35 5.68 0.2112
WVFGRD96 6.0 225 5 -30 5.72 0.3450
WVFGRD96 8.0 225 10 -30 5.84 0.4391
WVFGRD96 10.0 235 10 -20 5.88 0.5386
WVFGRD96 12.0 255 5 0 5.92 0.6177
WVFGRD96 14.0 165 80 85 5.97 0.6869
WVFGRD96 16.0 165 75 85 6.01 0.7436
WVFGRD96 18.0 165 75 85 6.05 0.7819
WVFGRD96 20.0 335 15 85 6.08 0.8016
WVFGRD96 22.0 335 15 85 6.12 0.8009
WVFGRD96 24.0 330 15 80 6.15 0.7829
WVFGRD96 26.0 330 15 75 6.16 0.7500
WVFGRD96 28.0 165 75 95 6.18 0.7056
WVFGRD96 30.0 335 15 85 6.19 0.6532
WVFGRD96 32.0 160 70 90 6.19 0.5973
WVFGRD96 34.0 360 20 110 6.19 0.5376
WVFGRD96 36.0 340 15 90 6.19 0.4821
WVFGRD96 38.0 160 75 90 6.18 0.4338
WVFGRD96 40.0 335 15 80 6.30 0.3872
WVFGRD96 42.0 160 75 90 6.30 0.3437
WVFGRD96 44.0 160 70 80 6.30 0.3152
WVFGRD96 46.0 150 70 65 6.31 0.2960
WVFGRD96 48.0 150 70 65 6.32 0.2821
WVFGRD96 50.0 150 70 65 6.33 0.2658
WVFGRD96 52.0 155 70 70 6.33 0.2498
WVFGRD96 54.0 155 70 70 6.34 0.2360
WVFGRD96 56.0 155 70 70 6.34 0.2220
WVFGRD96 58.0 165 70 90 6.35 0.2091
WVFGRD96 60.0 165 70 90 6.36 0.2076
WVFGRD96 62.0 330 20 70 6.37 0.2049
WVFGRD96 64.0 330 20 70 6.38 0.2007
WVFGRD96 66.0 345 15 90 6.38 0.1970
WVFGRD96 68.0 340 15 85 6.39 0.1934
WVFGRD96 70.0 165 75 90 6.40 0.1909
WVFGRD96 72.0 335 30 70 6.36 0.1888
WVFGRD96 74.0 335 30 70 6.36 0.1898
WVFGRD96 76.0 340 25 80 6.38 0.1902
WVFGRD96 78.0 340 25 80 6.38 0.1897
WVFGRD96 80.0 175 65 100 6.38 0.1892
WVFGRD96 82.0 165 70 90 6.41 0.1906
WVFGRD96 84.0 340 20 85 6.41 0.1915
WVFGRD96 86.0 165 70 90 6.41 0.1929
WVFGRD96 88.0 165 70 90 6.41 0.1945
WVFGRD96 90.0 185 40 -70 6.27 0.1953
WVFGRD96 92.0 190 40 -65 6.27 0.1979
WVFGRD96 94.0 185 40 -70 6.28 0.2071
WVFGRD96 96.0 190 40 -65 6.29 0.2096
WVFGRD96 98.0 185 40 -70 6.29 0.2179
WVFGRD96 100.0 185 40 -70 6.30 0.2227
WVFGRD96 102.0 185 40 -70 6.30 0.2290
WVFGRD96 104.0 185 40 -70 6.31 0.2348
WVFGRD96 106.0 180 45 -75 6.31 0.2357
WVFGRD96 108.0 180 45 -75 6.32 0.2445
The best solution is
WVFGRD96 20.0 335 15 85 6.08 0.8016
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
cut a -30 a 180 rtr taper w 0.1 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.
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 WUS used for the waveform synthetic seismograms and for the surface wave eigenfunctions and dispersion is as follows:
MODEL.01
Model after 8 iterations
ISOTROPIC
KGS
FLAT 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
1.9000 3.4065 2.0089 2.2150 0.302E-02 0.679E-02 0.00 0.00 1.00 1.00
6.1000 5.5445 3.2953 2.6089 0.349E-02 0.784E-02 0.00 0.00 1.00 1.00
13.0000 6.2708 3.7396 2.7812 0.212E-02 0.476E-02 0.00 0.00 1.00 1.00
19.0000 6.4075 3.7680 2.8223 0.111E-02 0.249E-02 0.00 0.00 1.00 1.00
0.0000 7.9000 4.6200 3.2760 0.164E-10 0.370E-10 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: