2011/04/22 00:06:03 63.989 -130.981 15 4.20 Yukon, Canada
USGS Felt map for this earthquake
USGS/SLU Moment Tensor Solution ENS 2011/04/22 00:06:03:1 63.99 -130.98 15.0 4.2 Yukon, Canada Stations used: AK.BAL AK.CCB AK.CTG AK.DHY AK.HDA AK.KLU AK.MCK AK.MDM AK.RAG AK.RND AK.SCM AK.TGL AK.WRH AT.MENT AT.SKAG CN.BVCY CN.DAWY CN.DLBC CN.HPLN CN.HYT CN.INK CN.SMPN CN.WHY CN.YUK1 CN.YUK5 CN.YUK7 IU.COLA US.EGAK US.WRAK Filtering commands used: hp c 0.02 n 3 lp c 0.06 n 3 Best Fitting Double Couple Mo = 2.11e+22 dyne-cm Mw = 4.15 Z = 11 km Plane Strike Dip Rake NP1 60 90 -10 NP2 150 80 -180 Principal Axes: Axis Value Plunge Azimuth T 2.11e+22 7 105 N 0.00e+00 80 240 P -2.11e+22 7 15 Moment Tensor: (dyne-cm) Component Value Mxx -1.80e+22 Mxy -1.04e+22 Mxz -3.18e+21 Myy 1.80e+22 Myz 1.84e+21 Mzz 3.21e+14 ---------- P - #------------- ----- ####------------------------ ######------------------------ ########-------------------------- ##########-------------------------- ############---------------------##### ##############-----------------######### ###############-------------############ #################---------################ ##################-----################### ########################################## ################----################## # ############--------################# T #########------------################ #####----------------################# ----------------------############## ----------------------############ ---------------------######### ----------------------###### ---------------------# -------------- Global CMT Convention Moment Tensor: R T P 3.21e+14 -3.18e+21 -1.84e+21 -3.18e+21 -1.80e+22 1.04e+22 -1.84e+21 1.04e+22 1.80e+22 Details of the solution is found at http://www.eas.slu.edu/eqc/eqc_mt/MECH.NA/20110422000603/index.html |
STK = 60 DIP = 90 RAKE = -10 MW = 4.15 HS = 11.0
The NDK file is 20110422000603.ndk The waveform inversion is preferred.
The following compares this source inversion to others
USGS/SLU Moment Tensor Solution ENS 2011/04/22 00:06:03:1 63.99 -130.98 15.0 4.2 Yukon, Canada Stations used: AK.BAL AK.CCB AK.CTG AK.DHY AK.HDA AK.KLU AK.MCK AK.MDM AK.RAG AK.RND AK.SCM AK.TGL AK.WRH AT.MENT AT.SKAG CN.BVCY CN.DAWY CN.DLBC CN.HPLN CN.HYT CN.INK CN.SMPN CN.WHY CN.YUK1 CN.YUK5 CN.YUK7 IU.COLA US.EGAK US.WRAK Filtering commands used: hp c 0.02 n 3 lp c 0.06 n 3 Best Fitting Double Couple Mo = 2.11e+22 dyne-cm Mw = 4.15 Z = 11 km Plane Strike Dip Rake NP1 60 90 -10 NP2 150 80 -180 Principal Axes: Axis Value Plunge Azimuth T 2.11e+22 7 105 N 0.00e+00 80 240 P -2.11e+22 7 15 Moment Tensor: (dyne-cm) Component Value Mxx -1.80e+22 Mxy -1.04e+22 Mxz -3.18e+21 Myy 1.80e+22 Myz 1.84e+21 Mzz 3.21e+14 ---------- P - #------------- ----- ####------------------------ ######------------------------ ########-------------------------- ##########-------------------------- ############---------------------##### ##############-----------------######### ###############-------------############ #################---------################ ##################-----################### ########################################## ################----################## # ############--------################# T #########------------################ #####----------------################# ----------------------############## ----------------------############ ---------------------######### ----------------------###### ---------------------# -------------- Global CMT Convention Moment Tensor: R T P 3.21e+14 -3.18e+21 -1.84e+21 -3.18e+21 -1.80e+22 1.04e+22 -1.84e+21 1.04e+22 1.80e+22 Details of the solution is found at http://www.eas.slu.edu/eqc/eqc_mt/MECH.NA/20110422000603/index.html USGS/SLU Moment Tensor Solution ENS 2011/04/22 00:06:04:2 63.88 -130.39 10.0 4.2 Yukon, Canada Stations used: AK.BAL AK.CCB AK.CTG AK.DHY AK.HDA AK.KLU AK.MCK AK.MDM AK.RAG AK.RND AK.SCM AK.TGL AK.WRH AT.MENT AT.SKAG CN.BVCY CN.DAWY CN.DLBC CN.HPLN CN.HYT CN.INK CN.SMPN CN.WHY CN.YUK1 CN.YUK5 CN.YUK7 IU.COLA US.EGAK US.WRAK Filtering commands used: hp c 0.02 n 3 lp c 0.06 n 3 Best Fitting Double Couple Mo = 2.11e+22 dyne-cm Mw = 4.15 Z = 11 km Plane Strike Dip Rake NP1 60 90 -10 NP2 150 80 -180 Principal Axes: Axis Value Plunge Azimuth T 2.11e+22 7 105 N 0.00e+00 80 240 P -2.11e+22 7 15 Moment Tensor: (dyne-cm) Component Value Mxx -1.80e+22 Mxy -1.04e+22 Mxz -3.18e+21 Myy 1.80e+22 Myz 1.84e+21 Mzz 3.21e+14 ---------- P - #------------- ----- ####------------------------ ######------------------------ ########-------------------------- ##########-------------------------- ############---------------------##### ##############-----------------######### ###############-------------############ #################---------################ ##################-----################### ########################################## ################----################## # ############--------################# T #########------------################ #####----------------################# ----------------------############## ----------------------############ ---------------------######### ----------------------###### ---------------------# -------------- Global CMT Convention Moment Tensor: R T P 3.21e+14 -3.18e+21 -1.84e+21 -3.18e+21 -1.80e+22 1.04e+22 -1.84e+21 1.04e+22 1.80e+22 Details of the solution is found at http://www.eas.slu.edu/Earthquake_Center/MECH.NA/20110422000604/index.html |
(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 0.06 n 3The results of this grid search from 0.5 to 19 km depth are as follow:
DEPTH STK DIP RAKE MW FIT WVFGRD96 0.5 65 90 -15 3.96 0.4233 WVFGRD96 1.0 65 90 -15 3.98 0.4503 WVFGRD96 2.0 245 85 5 4.02 0.4994 WVFGRD96 3.0 65 90 0 4.04 0.5350 WVFGRD96 4.0 60 90 0 4.07 0.5619 WVFGRD96 5.0 240 85 -5 4.09 0.5810 WVFGRD96 6.0 240 80 -5 4.10 0.5949 WVFGRD96 7.0 240 80 -5 4.11 0.6051 WVFGRD96 8.0 60 85 -10 4.13 0.6142 WVFGRD96 9.0 60 85 -10 4.13 0.6204 WVFGRD96 10.0 60 85 -10 4.15 0.6255 WVFGRD96 11.0 60 90 -10 4.15 0.6273 WVFGRD96 12.0 60 90 -10 4.16 0.6270 WVFGRD96 13.0 60 90 -10 4.17 0.6247 WVFGRD96 14.0 60 90 -5 4.17 0.6215 WVFGRD96 15.0 240 90 5 4.18 0.6172 WVFGRD96 16.0 60 90 -5 4.18 0.6133 WVFGRD96 17.0 60 90 -5 4.19 0.6085 WVFGRD96 18.0 60 85 0 4.20 0.6030 WVFGRD96 19.0 240 90 0 4.21 0.5976 WVFGRD96 20.0 240 90 -5 4.21 0.5928 WVFGRD96 21.0 60 85 0 4.22 0.5868 WVFGRD96 22.0 60 85 0 4.22 0.5791 WVFGRD96 23.0 240 90 -5 4.23 0.5702 WVFGRD96 24.0 60 85 0 4.24 0.5618 WVFGRD96 25.0 240 90 -5 4.24 0.5523 WVFGRD96 26.0 60 85 0 4.25 0.5429 WVFGRD96 27.0 240 90 -5 4.25 0.5330 WVFGRD96 28.0 240 90 -5 4.26 0.5236 WVFGRD96 29.0 240 90 -5 4.27 0.5133
The best solution is
WVFGRD96 11.0 60 90 -10 4.15 0.6273
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 0.06 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 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: