USGS/SLU Moment Tensor Solution ENS 2022/07/12 02:58:59:0 60.40 -149.01 30.1 4.3 Alaska Stations used: AK.BRLK AK.CAPN AK.FID AK.FIRE AK.GLB AK.GLI AK.K24K AK.KLU AK.MCAR AK.P23K AK.RC01 AK.RIDG AK.SCM AK.SKN AK.SWD AV.ILS Filtering commands used: cut o DIST/3.3 -40 o DIST/3.3 +50 rtr taper w 0.1 hp c 0.03 n 3 lp c 0.08 n 3 Best Fitting Double Couple Mo = 7.59e+22 dyne-cm Mw = 4.52 Z = 41 km Plane Strike Dip Rake NP1 210 60 -65 NP2 347 38 -126 Principal Axes: Axis Value Plunge Azimuth T 7.59e+22 12 282 N 0.00e+00 21 17 P -7.59e+22 65 166 Moment Tensor: (dyne-cm) Component Value Mxx -9.16e+21 Mxy -1.19e+22 Mxz 3.11e+22 Myy 6.87e+22 Myz -2.18e+22 Mzz -5.95e+22 ######-------- #############-------## ############################ #################-----######## #################--------######### ################------------######## ###############---------------######## ############----------------######### T ###########------------------######## # ##########--------------------######## #############---------------------######## ############----------------------######## ###########-----------------------######## ##########---------- ----------####### #########----------- P ----------####### ########----------- ----------###### #######-----------------------###### ######----------------------###### ####---------------------##### ###--------------------##### -------------------### -------------# Global CMT Convention Moment Tensor: R T P -5.95e+22 3.11e+22 2.18e+22 3.11e+22 -9.16e+21 1.19e+22 2.18e+22 1.19e+22 6.87e+22 Details of the solution is found at http://www.eas.slu.edu/eqc/eqc_mt/MECH.NA/20220712025859/index.html |
STK = 210 DIP = 60 RAKE = -65 MW = 4.52 HS = 41.0
The NDK file is 20220712025859.ndk The waveform inversion is preferred.
The following compares this source inversion to others
USGS/SLU Moment Tensor Solution ENS 2022/07/12 02:58:59:0 60.40 -149.01 30.1 4.3 Alaska Stations used: AK.BRLK AK.CAPN AK.FID AK.FIRE AK.GLB AK.GLI AK.K24K AK.KLU AK.MCAR AK.P23K AK.RC01 AK.RIDG AK.SCM AK.SKN AK.SWD AV.ILS Filtering commands used: cut o DIST/3.3 -40 o DIST/3.3 +50 rtr taper w 0.1 hp c 0.03 n 3 lp c 0.08 n 3 Best Fitting Double Couple Mo = 7.59e+22 dyne-cm Mw = 4.52 Z = 41 km Plane Strike Dip Rake NP1 210 60 -65 NP2 347 38 -126 Principal Axes: Axis Value Plunge Azimuth T 7.59e+22 12 282 N 0.00e+00 21 17 P -7.59e+22 65 166 Moment Tensor: (dyne-cm) Component Value Mxx -9.16e+21 Mxy -1.19e+22 Mxz 3.11e+22 Myy 6.87e+22 Myz -2.18e+22 Mzz -5.95e+22 ######-------- #############-------## ############################ #################-----######## #################--------######### ################------------######## ###############---------------######## ############----------------######### T ###########------------------######## # ##########--------------------######## #############---------------------######## ############----------------------######## ###########-----------------------######## ##########---------- ----------####### #########----------- P ----------####### ########----------- ----------###### #######-----------------------###### ######----------------------###### ####---------------------##### ###--------------------##### -------------------### -------------# Global CMT Convention Moment Tensor: R T P -5.95e+22 3.11e+22 2.18e+22 3.11e+22 -9.16e+21 1.19e+22 2.18e+22 1.19e+22 6.87e+22 Details of the solution is found at http://www.eas.slu.edu/eqc/eqc_mt/MECH.NA/20220712025859/index.html |
Regional Moment Tensor (Mwr) Moment 4.726e+15 N-m Magnitude 4.38 Mwr Depth 35.0 km Percent DC 66% Half Duration - Catalog US Data Source US 2 Contributor US 2 Nodal Planes Plane Strike Dip Rake NP1 355 48 -118 NP2 214 49 -62 Principal Axes Axis Value Plunge Azimuth T 5.098e+15 N-m 0 284 N -0.861e+15 N-m 21 14 P -4.237e+15 N-m 69 193 |
(a) ML computed using the IASPEI formula for Horizontal components; (b) ML residuals computed using a modified IASPEI formula that accounts for path specific attenuation; the values used for the trimmed mean are indicated. The ML relation used for each figure is given at the bottom of each plot.
(a) ML computed using the IASPEI formula for Vertical components (research); (b) ML residuals computed using a modified IASPEI formula that accounts for path specific attenuation; the values used for the trimmed mean are indicated. The ML relation used for each figure is given at the bottom of each plot.
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 o DIST/3.3 -40 o DIST/3.3 +50 rtr taper w 0.1 hp c 0.03 n 3 lp c 0.08 n 3The results of this grid search are as follow:
DEPTH STK DIP RAKE MW FIT WVFGRD96 1.0 210 50 85 3.79 0.1947 WVFGRD96 2.0 80 45 95 3.96 0.2529 WVFGRD96 3.0 180 50 -95 3.97 0.2744 WVFGRD96 4.0 185 50 -85 4.00 0.2639 WVFGRD96 5.0 225 80 50 3.98 0.3009 WVFGRD96 6.0 225 75 45 4.00 0.3304 WVFGRD96 7.0 225 75 45 4.02 0.3538 WVFGRD96 8.0 225 80 50 4.08 0.3690 WVFGRD96 9.0 225 80 45 4.09 0.3828 WVFGRD96 10.0 225 80 45 4.10 0.3926 WVFGRD96 11.0 225 80 45 4.12 0.3986 WVFGRD96 12.0 40 90 -45 4.13 0.3986 WVFGRD96 13.0 225 80 40 4.14 0.4032 WVFGRD96 14.0 225 80 40 4.16 0.4033 WVFGRD96 15.0 225 80 40 4.17 0.4022 WVFGRD96 16.0 230 80 40 4.17 0.4014 WVFGRD96 17.0 230 80 40 4.18 0.4008 WVFGRD96 18.0 230 80 40 4.19 0.3997 WVFGRD96 19.0 215 70 -45 4.21 0.4017 WVFGRD96 20.0 220 70 -45 4.21 0.4060 WVFGRD96 21.0 220 70 -45 4.23 0.4109 WVFGRD96 22.0 220 70 -45 4.24 0.4139 WVFGRD96 23.0 220 70 -45 4.25 0.4159 WVFGRD96 24.0 220 75 -45 4.26 0.4173 WVFGRD96 25.0 220 75 -45 4.27 0.4195 WVFGRD96 26.0 220 75 -45 4.28 0.4215 WVFGRD96 27.0 220 75 -45 4.29 0.4227 WVFGRD96 28.0 220 70 -45 4.30 0.4255 WVFGRD96 29.0 220 65 -45 4.31 0.4315 WVFGRD96 30.0 220 65 -45 4.32 0.4384 WVFGRD96 31.0 220 65 -45 4.33 0.4473 WVFGRD96 32.0 215 60 -50 4.35 0.4558 WVFGRD96 33.0 215 60 -55 4.36 0.4635 WVFGRD96 34.0 215 60 -55 4.37 0.4695 WVFGRD96 35.0 215 60 -55 4.38 0.4743 WVFGRD96 36.0 215 60 -55 4.39 0.4767 WVFGRD96 37.0 215 60 -55 4.40 0.4771 WVFGRD96 38.0 215 60 -55 4.41 0.4761 WVFGRD96 39.0 215 60 -55 4.42 0.4730 WVFGRD96 40.0 210 60 -65 4.50 0.4862 WVFGRD96 41.0 210 60 -65 4.52 0.4864 WVFGRD96 42.0 210 60 -65 4.52 0.4848 WVFGRD96 43.0 205 55 -65 4.54 0.4832 WVFGRD96 44.0 205 55 -65 4.54 0.4818 WVFGRD96 45.0 205 55 -65 4.55 0.4793 WVFGRD96 46.0 205 55 -65 4.56 0.4767 WVFGRD96 47.0 205 55 -65 4.56 0.4744 WVFGRD96 48.0 205 55 -65 4.57 0.4712 WVFGRD96 49.0 205 55 -65 4.57 0.4682 WVFGRD96 50.0 205 55 -65 4.58 0.4648 WVFGRD96 51.0 205 55 -65 4.58 0.4605 WVFGRD96 52.0 205 55 -65 4.59 0.4561 WVFGRD96 53.0 205 55 -65 4.59 0.4526 WVFGRD96 54.0 205 55 -65 4.59 0.4537 WVFGRD96 55.0 205 55 -60 4.60 0.4537 WVFGRD96 56.0 205 55 -60 4.60 0.4539 WVFGRD96 57.0 205 55 -60 4.60 0.4537 WVFGRD96 58.0 205 55 -60 4.61 0.4531 WVFGRD96 59.0 210 60 -55 4.60 0.4514
The best solution is
WVFGRD96 41.0 210 60 -65 4.52 0.4864
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 o DIST/3.3 -40 o DIST/3.3 +50 rtr taper w 0.1 hp c 0.03 n 3 lp c 0.08 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 Bureau of Mines, UC Berkely, Caltech, UC San Diego, Saint Louis University, University of Memphis, Lamont Doherty Earth Observatory, the Oklahoma Geological Survey, TexNet, the Iris stations, the Transportable Array of EarthScope and other networks.
The WUS.model 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: