USGS/SLU Moment Tensor Solution ENS 2022/06/29 23:03:01:0 34.17 -80.73 3.0 3.6 S. Carolina Stations used: CO.BIRD CO.CASEE CO.CSB CO.TEEBA ET.CPCT IM.TKL N4.152A N4.154A N4.257A N4.456A N4.KMSC N4.S54A N4.S57A N4.T57A N4.T59A N4.TIGA N4.U54A N4.U56A N4.V53A N4.V55A N4.V58A N4.V61A N4.W50A N4.W52A N4.W57A N4.W59A N4.X51A N4.Y52A N4.Y58A N4.Y60A US.GOGA US.NHSC US.TZTN Filtering commands used: cut o DIST/3.3 -30 o DIST/3.3 +40 rtr taper w 0.1 hp c 0.03 n 3 lp c 0.08 n 3 Best Fitting Double Couple Mo = 2.48e+21 dyne-cm Mw = 3.53 Z = 2 km Plane Strike Dip Rake NP1 201 81 155 NP2 295 65 10 Principal Axes: Axis Value Plunge Azimuth T 2.48e+21 24 155 N 0.00e+00 63 2 P -2.48e+21 11 250 Moment Tensor: (dyne-cm) Component Value Mxx 1.43e+21 Mxy -1.55e+21 Mxz -6.88e+20 Myy -1.76e+21 Myz 8.20e+20 Mzz 3.30e+20 ############## #################----- ###################--------- ###################----------- ####################-------------- ####################---------------- ---------------#####------------------ --------------------#------------------- -------------------######--------------- --------------------#########------------- -------------------#############---------- ------------------################-------- ------------------##################------ - ------------####################---- - P -----------#######################-- -----------######################## ------------######################## -----------########### ######### --------############ T ####### -------############ ###### ----################## ############## Global CMT Convention Moment Tensor: R T P 3.30e+20 -6.88e+20 -8.20e+20 -6.88e+20 1.43e+21 1.55e+21 -8.20e+20 1.55e+21 -1.76e+21 Details of the solution is found at http://www.eas.slu.edu/eqc/eqc_mt/MECH.NA/20220629230301/index.html |
STK = 295 DIP = 65 RAKE = 10 MW = 3.53 HS = 2.0
The NDK file is 20220629230301.ndk The waveform inversion is preferred.
The following compares this source inversion to others
USGS/SLU Moment Tensor Solution ENS 2022/06/29 23:03:01:0 34.17 -80.73 3.0 3.6 S. Carolina Stations used: CO.BIRD CO.CASEE CO.CSB CO.TEEBA ET.CPCT IM.TKL N4.152A N4.154A N4.257A N4.456A N4.KMSC N4.S54A N4.S57A N4.T57A N4.T59A N4.TIGA N4.U54A N4.U56A N4.V53A N4.V55A N4.V58A N4.V61A N4.W50A N4.W52A N4.W57A N4.W59A N4.X51A N4.Y52A N4.Y58A N4.Y60A US.GOGA US.NHSC US.TZTN Filtering commands used: cut o DIST/3.3 -30 o DIST/3.3 +40 rtr taper w 0.1 hp c 0.03 n 3 lp c 0.08 n 3 Best Fitting Double Couple Mo = 2.48e+21 dyne-cm Mw = 3.53 Z = 2 km Plane Strike Dip Rake NP1 201 81 155 NP2 295 65 10 Principal Axes: Axis Value Plunge Azimuth T 2.48e+21 24 155 N 0.00e+00 63 2 P -2.48e+21 11 250 Moment Tensor: (dyne-cm) Component Value Mxx 1.43e+21 Mxy -1.55e+21 Mxz -6.88e+20 Myy -1.76e+21 Myz 8.20e+20 Mzz 3.30e+20 ############## #################----- ###################--------- ###################----------- ####################-------------- ####################---------------- ---------------#####------------------ --------------------#------------------- -------------------######--------------- --------------------#########------------- -------------------#############---------- ------------------################-------- ------------------##################------ - ------------####################---- - P -----------#######################-- -----------######################## ------------######################## -----------########### ######### --------############ T ####### -------############ ###### ----################## ############## Global CMT Convention Moment Tensor: R T P 3.30e+20 -6.88e+20 -8.20e+20 -6.88e+20 1.43e+21 1.55e+21 -8.20e+20 1.55e+21 -1.76e+21 Details of the solution is found at http://www.eas.slu.edu/eqc/eqc_mt/MECH.NA/20220629230301/index.html |
Regional Moment Tensor (Mwr) Moment 3.185e+14 N-m Magnitude 3.60 Mwr Depth 2.0 km Percent DC 91% Half Duration - Catalog US Data Source US 3 Contributor US 3 Nodal Planes Plane Strike Dip Rake NP1 20 50 167 NP2 118 80 41 Principal Axes Axis Value Plunge Azimuth T 3.105e+14 N-m 35 347 N 0.154e+14 N-m 48 129 P -3.259e+14 N-m 20 243 |
(a) mLg computed using the IASPEI formula; (b) mLg residuals ; the values used for the trimmed mean are indicated.
(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 -30 o DIST/3.3 +40 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 1.0 295 55 10 3.53 0.6523 WVFGRD96 2.0 295 65 10 3.53 0.6618 WVFGRD96 3.0 295 65 10 3.54 0.6522 WVFGRD96 4.0 295 70 15 3.55 0.6381 WVFGRD96 5.0 295 75 25 3.56 0.6267 WVFGRD96 6.0 120 70 30 3.57 0.6220 WVFGRD96 7.0 115 75 30 3.57 0.6226 WVFGRD96 8.0 115 75 30 3.58 0.6218 WVFGRD96 9.0 115 75 25 3.58 0.6206 WVFGRD96 10.0 115 75 30 3.60 0.6185 WVFGRD96 11.0 115 75 30 3.61 0.6150 WVFGRD96 12.0 115 75 25 3.61 0.6107 WVFGRD96 13.0 115 75 25 3.62 0.6059 WVFGRD96 14.0 115 75 25 3.62 0.6002 WVFGRD96 15.0 115 75 25 3.63 0.5938 WVFGRD96 16.0 115 75 25 3.64 0.5873 WVFGRD96 17.0 290 80 -25 3.64 0.5809 WVFGRD96 18.0 290 80 -25 3.65 0.5773 WVFGRD96 19.0 290 80 -20 3.66 0.5728 WVFGRD96 20.0 115 70 -15 3.68 0.5714 WVFGRD96 21.0 115 70 -15 3.68 0.5678 WVFGRD96 22.0 115 70 -15 3.69 0.5633 WVFGRD96 23.0 115 70 -15 3.70 0.5593 WVFGRD96 24.0 110 70 -15 3.70 0.5554 WVFGRD96 25.0 115 75 -15 3.71 0.5501 WVFGRD96 26.0 115 75 -15 3.71 0.5442 WVFGRD96 27.0 115 75 -15 3.72 0.5390 WVFGRD96 28.0 115 75 -15 3.73 0.5327 WVFGRD96 29.0 115 75 -15 3.73 0.5254
The best solution is
WVFGRD96 2.0 295 65 10 3.53 0.6618
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 -30 o DIST/3.3 +40 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 CUS.model used for the waveform synthetic seismograms and for the surface wave eigenfunctions and dispersion is as follows:
MODEL.01 CUS Model with Q from simple gamma values 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 1.0000 5.0000 2.8900 2.5000 0.172E-02 0.387E-02 0.00 0.00 1.00 1.00 9.0000 6.1000 3.5200 2.7300 0.160E-02 0.363E-02 0.00 0.00 1.00 1.00 10.0000 6.4000 3.7000 2.8200 0.149E-02 0.336E-02 0.00 0.00 1.00 1.00 20.0000 6.7000 3.8700 2.9020 0.000E-04 0.000E-04 0.00 0.00 1.00 1.00 0.0000 8.1500 4.7000 3.3640 0.194E-02 0.431E-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: