2011/06/16 19:06:05 60.765 -151.048 57 5.20 Alaska
USGS Felt map for this earthquake
USGS/SLU Moment Tensor Solution ENS 2011/06/16 19:06:05:0 60.76 -151.05 57.0 5.2 Alaska Stations used: AK.BPAW AK.BRLK AK.BWN AK.CNP AK.DIV AK.HOM AK.KLU AK.KTH AK.MCK AK.PPLA AK.RC01 AK.RND AK.SAW AK.SCM AK.SSN AK.SWD AT.MENT AT.PMR II.KDAK Filtering commands used: hp c 0.02 n 3 lp c 0.05 n 3 Best Fitting Double Couple Mo = 3.85e+23 dyne-cm Mw = 4.99 Z = 74 km Plane Strike Dip Rake NP1 45 75 20 NP2 310 71 164 Principal Axes: Axis Value Plunge Azimuth T 3.85e+23 25 268 N 0.00e+00 65 80 P -3.85e+23 3 177 Moment Tensor: (dyne-cm) Component Value Mxx -3.82e+23 Mxy 3.29e+22 Mxz 1.44e+22 Myy 3.16e+23 Myz -1.47e+23 Mzz 6.58e+22 -------------- ---------------------- ---------------------------- -----------------------------# ######-------------------------### ############-------------------##### ################---------------####### ####################----------########## ######################-------########### #########################----############# #### ################################### #### T ##################----############# #### #################-------########### #####################----------######### ###################--------------####### ###############------------------##### ############---------------------### ########-------------------------# ###--------------------------- ---------------------------- ----------- -------- ------- P ---- Global CMT Convention Moment Tensor: R T P 6.58e+22 1.44e+22 1.47e+23 1.44e+22 -3.82e+23 -3.29e+22 1.47e+23 -3.29e+22 3.16e+23 Details of the solution is found at http://www.eas.slu.edu/eqc/eqc_mt/MECH.NA/20110616190605/index.html |
STK = 45 DIP = 75 RAKE = 20 MW = 4.99 HS = 74.0
The NDK file is 20110616190605.ndk The waveform inversion is preferred.
The following compares this source inversion to others
USGS/SLU Moment Tensor Solution ENS 2011/06/16 19:06:05:0 60.76 -151.05 57.0 5.2 Alaska Stations used: AK.BPAW AK.BRLK AK.BWN AK.CNP AK.DIV AK.HOM AK.KLU AK.KTH AK.MCK AK.PPLA AK.RC01 AK.RND AK.SAW AK.SCM AK.SSN AK.SWD AT.MENT AT.PMR II.KDAK Filtering commands used: hp c 0.02 n 3 lp c 0.05 n 3 Best Fitting Double Couple Mo = 3.85e+23 dyne-cm Mw = 4.99 Z = 74 km Plane Strike Dip Rake NP1 45 75 20 NP2 310 71 164 Principal Axes: Axis Value Plunge Azimuth T 3.85e+23 25 268 N 0.00e+00 65 80 P -3.85e+23 3 177 Moment Tensor: (dyne-cm) Component Value Mxx -3.82e+23 Mxy 3.29e+22 Mxz 1.44e+22 Myy 3.16e+23 Myz -1.47e+23 Mzz 6.58e+22 -------------- ---------------------- ---------------------------- -----------------------------# ######-------------------------### ############-------------------##### ################---------------####### ####################----------########## ######################-------########### #########################----############# #### ################################### #### T ##################----############# #### #################-------########### #####################----------######### ###################--------------####### ###############------------------##### ############---------------------### ########-------------------------# ###--------------------------- ---------------------------- ----------- -------- ------- P ---- Global CMT Convention Moment Tensor: R T P 6.58e+22 1.44e+22 1.47e+23 1.44e+22 -3.82e+23 -3.29e+22 1.47e+23 -3.29e+22 3.16e+23 Details of the solution is found at http://www.eas.slu.edu/eqc/eqc_mt/MECH.NA/20110616190605/index.html |
USGS/SLU Regional Moment Solution 11/06/16 19:06:05.42 Epicenter: 60.807 -151.216 MW 5.0 USGS/SLU REGIONAL MOMENT TENSOR Depth 66 No. of sta: 58 Moment Tensor; Scale 10**16 Nm Mrr= 0.17 Mtt=-3.62 Mpp= 3.45 Mrt= 0.40 Mrp= 1.31 Mtp=-0.15 Principal axes: T Val= 3.91 Plg=19 Azm=270 N -0.23 69 69 P -3.68 7 177 Best Double Couple:Mo=3.8*10**16 NP1:Strike= 45 Dip=81 Slip= 19 NP2: 312 71 171 |
(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:
hp c 0.02 n 3 lp c 0.05 n 3The results of this grid search from 0.5 to 19 km depth are as follow:
DEPTH STK DIP RAKE MW FIT WVFGRD96 0.5 315 70 15 4.16 0.2134 WVFGRD96 1.0 130 90 0 4.17 0.2321 WVFGRD96 2.0 315 75 15 4.28 0.2934 WVFGRD96 3.0 130 90 0 4.31 0.3228 WVFGRD96 4.0 310 85 0 4.34 0.3423 WVFGRD96 5.0 220 80 15 4.38 0.3570 WVFGRD96 6.0 220 80 15 4.41 0.3814 WVFGRD96 7.0 215 90 5 4.44 0.4071 WVFGRD96 8.0 220 85 15 4.47 0.4348 WVFGRD96 9.0 220 85 15 4.49 0.4543 WVFGRD96 10.0 40 90 -10 4.51 0.4660 WVFGRD96 11.0 220 85 15 4.53 0.4798 WVFGRD96 12.0 35 90 -15 4.54 0.4834 WVFGRD96 13.0 35 90 -15 4.55 0.4884 WVFGRD96 14.0 35 90 -10 4.56 0.4929 WVFGRD96 15.0 220 85 15 4.57 0.4991 WVFGRD96 16.0 35 90 -15 4.58 0.4999 WVFGRD96 17.0 220 85 15 4.59 0.5038 WVFGRD96 18.0 35 90 -10 4.59 0.5057 WVFGRD96 19.0 35 90 -10 4.60 0.5084 WVFGRD96 20.0 35 90 -10 4.61 0.5117 WVFGRD96 21.0 220 85 10 4.62 0.5164 WVFGRD96 22.0 35 90 -10 4.62 0.5188 WVFGRD96 23.0 35 90 -10 4.63 0.5215 WVFGRD96 24.0 215 90 10 4.64 0.5238 WVFGRD96 25.0 35 90 -10 4.64 0.5263 WVFGRD96 26.0 40 90 10 4.64 0.5287 WVFGRD96 27.0 40 90 10 4.65 0.5323 WVFGRD96 28.0 40 90 10 4.66 0.5366 WVFGRD96 29.0 215 85 -15 4.67 0.5429 WVFGRD96 30.0 215 85 -15 4.67 0.5481 WVFGRD96 31.0 40 85 10 4.69 0.5524 WVFGRD96 32.0 40 85 10 4.70 0.5592 WVFGRD96 33.0 40 85 10 4.71 0.5665 WVFGRD96 34.0 40 85 10 4.72 0.5743 WVFGRD96 35.0 220 90 -10 4.73 0.5775 WVFGRD96 36.0 220 90 -10 4.75 0.5850 WVFGRD96 37.0 40 85 10 4.76 0.5995 WVFGRD96 38.0 40 85 10 4.77 0.6087 WVFGRD96 39.0 220 90 -10 4.79 0.6082 WVFGRD96 40.0 40 80 20 4.82 0.6257 WVFGRD96 41.0 40 80 15 4.83 0.6297 WVFGRD96 42.0 40 80 15 4.83 0.6338 WVFGRD96 43.0 40 80 15 4.84 0.6377 WVFGRD96 44.0 40 80 15 4.85 0.6417 WVFGRD96 45.0 40 80 15 4.86 0.6455 WVFGRD96 46.0 40 80 15 4.86 0.6492 WVFGRD96 47.0 40 80 15 4.87 0.6531 WVFGRD96 48.0 40 80 15 4.88 0.6571 WVFGRD96 49.0 40 80 15 4.88 0.6613 WVFGRD96 50.0 40 80 15 4.89 0.6651 WVFGRD96 51.0 40 80 15 4.90 0.6685 WVFGRD96 52.0 40 80 15 4.90 0.6724 WVFGRD96 53.0 40 80 15 4.91 0.6766 WVFGRD96 54.0 40 80 15 4.91 0.6798 WVFGRD96 55.0 40 80 15 4.92 0.6825 WVFGRD96 56.0 40 80 15 4.93 0.6863 WVFGRD96 57.0 40 80 15 4.93 0.6895 WVFGRD96 58.0 40 80 15 4.93 0.6915 WVFGRD96 59.0 40 80 15 4.94 0.6948 WVFGRD96 60.0 40 80 20 4.94 0.6973 WVFGRD96 61.0 45 75 20 4.95 0.6989 WVFGRD96 62.0 45 75 20 4.95 0.7020 WVFGRD96 63.0 45 75 20 4.95 0.7038 WVFGRD96 64.0 45 75 20 4.96 0.7058 WVFGRD96 65.0 45 75 20 4.96 0.7079 WVFGRD96 66.0 45 75 20 4.96 0.7086 WVFGRD96 67.0 45 75 20 4.97 0.7107 WVFGRD96 68.0 45 75 20 4.97 0.7112 WVFGRD96 69.0 45 75 20 4.97 0.7126 WVFGRD96 70.0 45 75 20 4.98 0.7134 WVFGRD96 71.0 45 75 20 4.98 0.7137 WVFGRD96 72.0 45 75 20 4.98 0.7145 WVFGRD96 73.0 45 75 20 4.98 0.7139 WVFGRD96 74.0 45 75 20 4.99 0.7146 WVFGRD96 75.0 45 75 20 4.99 0.7139 WVFGRD96 76.0 45 75 20 4.99 0.7145 WVFGRD96 77.0 45 75 20 4.99 0.7132 WVFGRD96 78.0 45 75 20 5.00 0.7133 WVFGRD96 79.0 45 75 20 5.00 0.7122 WVFGRD96 80.0 45 75 20 5.00 0.7123 WVFGRD96 81.0 45 75 20 5.00 0.7105 WVFGRD96 82.0 45 75 20 5.00 0.7101 WVFGRD96 83.0 45 75 20 5.01 0.7088 WVFGRD96 84.0 45 75 20 5.01 0.7078 WVFGRD96 85.0 45 75 20 5.01 0.7062 WVFGRD96 86.0 45 75 20 5.01 0.7050 WVFGRD96 87.0 45 75 20 5.01 0.7037 WVFGRD96 88.0 45 75 20 5.01 0.7012 WVFGRD96 89.0 45 75 20 5.02 0.7006 WVFGRD96 90.0 40 80 20 5.02 0.6981 WVFGRD96 91.0 40 80 20 5.02 0.6973 WVFGRD96 92.0 40 80 20 5.02 0.6958 WVFGRD96 93.0 40 80 20 5.02 0.6939 WVFGRD96 94.0 40 80 25 5.02 0.6927 WVFGRD96 95.0 40 80 25 5.02 0.6906 WVFGRD96 96.0 40 80 25 5.02 0.6895 WVFGRD96 97.0 40 80 25 5.02 0.6878 WVFGRD96 98.0 40 80 25 5.02 0.6861 WVFGRD96 99.0 40 80 25 5.02 0.6842
The best solution is
WVFGRD96 74.0 45 75 20 4.99 0.7146
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
hp c 0.02 n 3 lp c 0.05 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 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: