2014/03/22 22:14:56 -19.709 -71.028 10.0 5.1 Chile
USGS Felt map for this earthquake
USGS/SLU Moment Tensor Solution
ENS 2014/03/22 22:14:56:0 -19.71 -71.03 10.0 5.1 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 = 3.02e+23 dyne-cm
Mw = 4.92
Z = 20 km
Plane Strike Dip Rake
NP1 171 77 98
NP2 320 15 60
Principal Axes:
Axis Value Plunge Azimuth
T 3.02e+23 57 91
N 0.00e+00 7 349
P -3.02e+23 32 255
Moment Tensor: (dyne-cm)
Component Value
Mxx -1.55e+22
Mxy -5.76e+22
Mxz 3.39e+22
Myy -1.15e+23
Myz 2.67e+23
Mzz 1.31e+23
###-----------
#------#########------
----------#############-----
-----------###############----
-------------#################----
--------------###################---
---------------####################---
----------------#####################---
----------------######################--
-----------------######################---
------------------########## ########---
------------------########## T #########--
------ ---------########## #########--
----- P ---------######################-
----- ----------####################--
-----------------####################-
-----------------##################-
----------------#################-
---------------###############
---------------#############
-------------#########
----------####
Global CMT Convention Moment Tensor:
R T P
1.31e+23 3.39e+22 -2.67e+23
3.39e+22 -1.55e+22 5.76e+22
-2.67e+23 5.76e+22 -1.15e+23
Details of the solution is found at
http://www.eas.slu.edu/eqc/eqc_mt/MECH.NA/20140322221456/index.html
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STK = 320
DIP = 15
RAKE = 60
MW = 4.92
HS = 20.0
The NDK file is 20140322221456.ndk The waveform inversion is preferred.
The following compares this source inversion to others
USGS/SLU Moment Tensor Solution
ENS 2014/03/22 22:14:56:0 -19.71 -71.03 10.0 5.1 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 = 3.02e+23 dyne-cm
Mw = 4.92
Z = 20 km
Plane Strike Dip Rake
NP1 171 77 98
NP2 320 15 60
Principal Axes:
Axis Value Plunge Azimuth
T 3.02e+23 57 91
N 0.00e+00 7 349
P -3.02e+23 32 255
Moment Tensor: (dyne-cm)
Component Value
Mxx -1.55e+22
Mxy -5.76e+22
Mxz 3.39e+22
Myy -1.15e+23
Myz 2.67e+23
Mzz 1.31e+23
###-----------
#------#########------
----------#############-----
-----------###############----
-------------#################----
--------------###################---
---------------####################---
----------------#####################---
----------------######################--
-----------------######################---
------------------########## ########---
------------------########## T #########--
------ ---------########## #########--
----- P ---------######################-
----- ----------####################--
-----------------####################-
-----------------##################-
----------------#################-
---------------###############
---------------#############
-------------#########
----------####
Global CMT Convention Moment Tensor:
R T P
1.31e+23 3.39e+22 -2.67e+23
3.39e+22 -1.55e+22 5.76e+22
-2.67e+23 5.76e+22 -1.15e+23
Details of the solution is found at
http://www.eas.slu.edu/eqc/eqc_mt/MECH.NA/20140322221456/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 0 50 90 4.56 0.3457
WVFGRD96 4.0 225 10 -40 4.55 0.2345
WVFGRD96 6.0 240 10 -25 4.59 0.3706
WVFGRD96 8.0 230 10 -35 4.70 0.4653
WVFGRD96 10.0 225 15 -40 4.74 0.5591
WVFGRD96 12.0 230 15 -35 4.77 0.6296
WVFGRD96 14.0 320 10 60 4.81 0.6821
WVFGRD96 16.0 325 15 65 4.85 0.7268
WVFGRD96 18.0 320 15 60 4.89 0.7549
WVFGRD96 20.0 320 15 60 4.92 0.7651
WVFGRD96 22.0 320 15 60 4.96 0.7568
WVFGRD96 24.0 315 15 55 4.98 0.7325
WVFGRD96 26.0 315 15 55 5.00 0.6934
WVFGRD96 28.0 320 15 65 5.02 0.6427
WVFGRD96 30.0 165 75 95 5.03 0.5846
WVFGRD96 32.0 335 20 80 5.02 0.5281
WVFGRD96 34.0 165 70 95 5.02 0.4693
WVFGRD96 36.0 330 20 75 5.02 0.4161
WVFGRD96 38.0 325 20 70 5.01 0.3718
WVFGRD96 40.0 20 10 -65 5.15 0.3600
WVFGRD96 42.0 30 20 -45 5.14 0.3353
WVFGRD96 44.0 35 25 -40 5.15 0.3232
WVFGRD96 46.0 35 25 -40 5.16 0.3120
WVFGRD96 48.0 30 25 -50 5.17 0.3066
WVFGRD96 50.0 25 20 -60 5.19 0.3053
WVFGRD96 52.0 25 20 -60 5.20 0.3059
WVFGRD96 54.0 25 20 -60 5.21 0.2970
WVFGRD96 56.0 30 20 -55 5.22 0.2935
WVFGRD96 58.0 20 15 -65 5.23 0.2906
WVFGRD96 60.0 25 15 -60 5.24 0.2882
WVFGRD96 62.0 20 15 -65 5.25 0.2871
WVFGRD96 64.0 35 15 -50 5.25 0.2742
WVFGRD96 66.0 20 15 -65 5.27 0.2729
WVFGRD96 68.0 25 15 -60 5.28 0.2678
WVFGRD96 70.0 175 80 -95 5.27 0.2624
WVFGRD96 72.0 345 70 75 5.15 0.2520
WVFGRD96 74.0 340 70 75 5.15 0.2546
WVFGRD96 76.0 340 70 75 5.16 0.2568
WVFGRD96 78.0 335 70 70 5.16 0.2551
WVFGRD96 80.0 340 65 70 5.16 0.2571
WVFGRD96 82.0 340 65 70 5.16 0.2561
WVFGRD96 84.0 340 65 70 5.16 0.2580
WVFGRD96 86.0 340 60 70 5.16 0.2591
WVFGRD96 88.0 340 60 70 5.16 0.2588
WVFGRD96 90.0 340 60 70 5.16 0.2599
WVFGRD96 92.0 195 35 -65 5.16 0.2637
WVFGRD96 94.0 195 40 -65 5.17 0.2694
WVFGRD96 96.0 190 40 -70 5.17 0.2713
WVFGRD96 98.0 190 40 -70 5.17 0.2771
WVFGRD96 100.0 190 40 -70 5.18 0.2823
WVFGRD96 102.0 190 40 -70 5.18 0.2869
WVFGRD96 104.0 190 40 -70 5.19 0.2926
WVFGRD96 106.0 190 45 -75 5.19 0.2960
WVFGRD96 108.0 190 45 -75 5.19 0.3011
The best solution is
WVFGRD96 20.0 320 15 60 4.92 0.7651
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: