2014/03/24 12:32:50 -19.785 -70.819 20.8 4.9 Chile
USGS Felt map for this earthquake
USGS/SLU Moment Tensor Solution
ENS 2014/03/24 12:32:50:0 -19.78 -70.82 20.8 4.9 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 0.06 n 3
Best Fitting Double Couple
Mo = 2.72e+23 dyne-cm
Mw = 4.89
Z = 22 km
Plane Strike Dip Rake
NP1 165 70 80
NP2 12 22 116
Principal Axes:
Axis Value Plunge Azimuth
T 2.72e+23 64 59
N 0.00e+00 9 168
P -2.72e+23 24 263
Moment Tensor: (dyne-cm)
Component Value
Mxx 1.07e+22
Mxy -4.61e+21
Mxz 6.88e+22
Myy -1.83e+23
Myz 1.94e+23
Mzz 1.72e+23
-############-
-----###############--
--------#################---
--------###################---
----------#####################---
-----------######################---
------------######################----
--------------######################----
--------------######### ##########----
---------------######### T ##########-----
----------------######## ##########-----
---- ---------#####################-----
---- P ---------#####################-----
--- ----------####################----
-----------------##################-----
----------------#################-----
----------------###############-----
----------------#############-----
---------------###########----
---------------########-----
--------------###-----
---------###--
Global CMT Convention Moment Tensor:
R T P
1.72e+23 6.88e+22 -1.94e+23
6.88e+22 1.07e+22 4.61e+21
-1.94e+23 4.61e+21 -1.83e+23
Details of the solution is found at
http://www.eas.slu.edu/eqc/eqc_mt/MECH.NA/20140324123250/index.html
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STK = 165
DIP = 70
RAKE = 80
MW = 4.89
HS = 22.0
The NDK file is 20140324123250.ndk The waveform inversion is preferred.
The following compares this source inversion to others
USGS/SLU Moment Tensor Solution
ENS 2014/03/24 12:32:50:0 -19.78 -70.82 20.8 4.9 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 0.06 n 3
Best Fitting Double Couple
Mo = 2.72e+23 dyne-cm
Mw = 4.89
Z = 22 km
Plane Strike Dip Rake
NP1 165 70 80
NP2 12 22 116
Principal Axes:
Axis Value Plunge Azimuth
T 2.72e+23 64 59
N 0.00e+00 9 168
P -2.72e+23 24 263
Moment Tensor: (dyne-cm)
Component Value
Mxx 1.07e+22
Mxy -4.61e+21
Mxz 6.88e+22
Myy -1.83e+23
Myz 1.94e+23
Mzz 1.72e+23
-############-
-----###############--
--------#################---
--------###################---
----------#####################---
-----------######################---
------------######################----
--------------######################----
--------------######### ##########----
---------------######### T ##########-----
----------------######## ##########-----
---- ---------#####################-----
---- P ---------#####################-----
--- ----------####################----
-----------------##################-----
----------------#################-----
----------------###############-----
----------------#############-----
---------------###########----
---------------########-----
--------------###-----
---------###--
Global CMT Convention Moment Tensor:
R T P
1.72e+23 6.88e+22 -1.94e+23
6.88e+22 1.07e+22 4.61e+21
-1.94e+23 4.61e+21 -1.83e+23
Details of the solution is found at
http://www.eas.slu.edu/eqc/eqc_mt/MECH.NA/20140324123250/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 0.06 n 3The results of this grid search from 0.5 to 19 km depth are as follow:
DEPTH STK DIP RAKE MW FIT
WVFGRD96 2.0 175 40 95 4.61 0.4025
WVFGRD96 4.0 240 10 -20 4.68 0.2828
WVFGRD96 6.0 260 5 0 4.69 0.4364
WVFGRD96 8.0 275 5 15 4.77 0.5327
WVFGRD96 10.0 295 10 35 4.78 0.6300
WVFGRD96 12.0 165 80 80 4.80 0.7132
WVFGRD96 14.0 165 75 80 4.82 0.7778
WVFGRD96 16.0 165 70 80 4.85 0.8236
WVFGRD96 18.0 165 70 80 4.86 0.8520
WVFGRD96 20.0 165 70 80 4.87 0.8656
WVFGRD96 22.0 165 70 80 4.89 0.8685
WVFGRD96 24.0 165 70 80 4.90 0.8627
WVFGRD96 26.0 165 75 80 4.91 0.8500
WVFGRD96 28.0 165 75 80 4.92 0.8322
WVFGRD96 30.0 165 75 80 4.93 0.8083
WVFGRD96 32.0 165 70 80 4.94 0.7798
WVFGRD96 34.0 165 75 80 4.95 0.7478
WVFGRD96 36.0 160 75 80 4.95 0.7151
WVFGRD96 38.0 165 75 80 4.96 0.6830
WVFGRD96 40.0 165 75 85 5.10 0.6532
WVFGRD96 42.0 165 75 85 5.10 0.6174
WVFGRD96 44.0 160 75 80 5.11 0.5829
WVFGRD96 46.0 160 75 80 5.11 0.5515
WVFGRD96 48.0 160 75 80 5.12 0.5220
WVFGRD96 50.0 160 75 75 5.12 0.4944
WVFGRD96 52.0 160 75 75 5.13 0.4696
WVFGRD96 54.0 160 75 75 5.13 0.4460
WVFGRD96 56.0 160 75 75 5.14 0.4240
WVFGRD96 58.0 160 80 75 5.14 0.4057
WVFGRD96 60.0 155 80 70 5.15 0.3890
WVFGRD96 62.0 155 80 70 5.15 0.3749
WVFGRD96 64.0 160 80 75 5.16 0.3618
WVFGRD96 66.0 345 70 80 5.14 0.3508
WVFGRD96 68.0 345 65 80 5.14 0.3432
WVFGRD96 70.0 345 65 80 5.15 0.3459
WVFGRD96 72.0 345 65 80 5.15 0.3382
WVFGRD96 74.0 350 60 80 5.15 0.3399
WVFGRD96 76.0 345 60 80 5.15 0.3346
WVFGRD96 78.0 345 60 80 5.16 0.3288
WVFGRD96 80.0 345 55 80 5.16 0.3315
WVFGRD96 82.0 350 55 80 5.16 0.3260
WVFGRD96 84.0 310 65 -70 5.17 0.3276
WVFGRD96 86.0 325 65 -85 5.17 0.3287
WVFGRD96 88.0 130 30 -95 5.18 0.3352
WVFGRD96 90.0 130 30 -95 5.19 0.3419
WVFGRD96 92.0 135 30 -90 5.19 0.3472
WVFGRD96 94.0 315 60 -90 5.20 0.3538
WVFGRD96 96.0 140 30 -90 5.20 0.3627
WVFGRD96 98.0 320 60 -90 5.21 0.3678
WVFGRD96 100.0 320 60 -90 5.21 0.3755
WVFGRD96 102.0 320 60 -90 5.22 0.3799
WVFGRD96 104.0 320 60 -90 5.22 0.3864
WVFGRD96 106.0 155 30 -75 5.24 0.3934
WVFGRD96 108.0 155 30 -75 5.24 0.3962
The best solution is
WVFGRD96 22.0 165 70 80 4.89 0.8685
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 0.06 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: