2014/07/25 10:54:49 58.358 -137.130 10.0 5.9 Alaska
USGS Felt map for this earthquake
USGS/SLU Moment Tensor Solution ENS 2014/07/25 10:54:49:0 58.36 -137.13 10.0 5.9 Alaska Stations used: AK.BAL AK.BARN AK.BESE AK.CRQ AK.CTG AK.GLB AK.ISLE AK.JIS AK.MCAR AK.PIN AK.TABL AK.TGL AK.VRDI AT.SIT AT.SKAG AT.YKU2 CN.DLBC CN.HYT CN.WHY US.WRAK Filtering commands used: cut o DIST/3.3 -40 o DIST/3.3 +60 rtr taper w 0.1 hp c 0.02 n 3 lp c 0.06 n 3 Best Fitting Double Couple Mo = 7.50e+24 dyne-cm Mw = 5.85 Z = 17 km Plane Strike Dip Rake NP1 316 76 164 NP2 50 75 15 Principal Axes: Axis Value Plunge Azimuth T 7.50e+24 21 273 N 0.00e+00 69 94 P -7.50e+24 0 3 Moment Tensor: (dyne-cm) Component Value Mxx -7.46e+24 Mxy -7.37e+23 Mxz 8.25e+22 Myy 6.49e+24 Myz -2.52e+24 Mzz 9.70e+23 ------- P ---- ----------- -------- ---------------------------- ###--------------------------- ########------------------------## ############--------------------#### ###############-----------------###### ###################-------------######## #####################---------########## ### #################-------############ ### T ###################---############## ### ####################-############### ########################----############## ####################---------########### ##################------------########## ##############----------------######## ##########--------------------###### #####-------------------------#### -----------------------------# ---------------------------- ---------------------- -------------- Global CMT Convention Moment Tensor: R T P 9.70e+23 8.25e+22 2.52e+24 8.25e+22 -7.46e+24 7.37e+23 2.52e+24 7.37e+23 6.49e+24 Details of the solution is found at http://www.eas.slu.edu/eqc/eqc_mt/MECH.NA/20140725105449/index.html |
STK = 50 DIP = 75 RAKE = 15 MW = 5.85 HS = 17.0
The NDK file is 20140725105449.ndk The waveform inversion is preferred.
The following compares this source inversion to others
USGS/SLU Moment Tensor Solution ENS 2014/07/25 10:54:49:0 58.36 -137.13 10.0 5.9 Alaska Stations used: AK.BAL AK.BARN AK.BESE AK.CRQ AK.CTG AK.GLB AK.ISLE AK.JIS AK.MCAR AK.PIN AK.TABL AK.TGL AK.VRDI AT.SIT AT.SKAG AT.YKU2 CN.DLBC CN.HYT CN.WHY US.WRAK Filtering commands used: cut o DIST/3.3 -40 o DIST/3.3 +60 rtr taper w 0.1 hp c 0.02 n 3 lp c 0.06 n 3 Best Fitting Double Couple Mo = 7.50e+24 dyne-cm Mw = 5.85 Z = 17 km Plane Strike Dip Rake NP1 316 76 164 NP2 50 75 15 Principal Axes: Axis Value Plunge Azimuth T 7.50e+24 21 273 N 0.00e+00 69 94 P -7.50e+24 0 3 Moment Tensor: (dyne-cm) Component Value Mxx -7.46e+24 Mxy -7.37e+23 Mxz 8.25e+22 Myy 6.49e+24 Myz -2.52e+24 Mzz 9.70e+23 ------- P ---- ----------- -------- ---------------------------- ###--------------------------- ########------------------------## ############--------------------#### ###############-----------------###### ###################-------------######## #####################---------########## ### #################-------############ ### T ###################---############## ### ####################-############### ########################----############## ####################---------########### ##################------------########## ##############----------------######## ##########--------------------###### #####-------------------------#### -----------------------------# ---------------------------- ---------------------- -------------- Global CMT Convention Moment Tensor: R T P 9.70e+23 8.25e+22 2.52e+24 8.25e+22 -7.46e+24 7.37e+23 2.52e+24 7.37e+23 6.49e+24 Details of the solution is found at http://www.eas.slu.edu/eqc/eqc_mt/MECH.NA/20140725105449/index.html |
Body-wave Moment Tensor (Mwb) Moment magnitude derived from a moment tensor inversion of long-period (~10 - 100 s) body-waves (P-, SH- ) at teleseismic distances (~30 to ~90 degrees). Moment 9.60e+17 N-m Magnitude 5.9 Percent DC 83% Depth 9.0 km Updated 2014-07-25 12:30:55 UTC Author us Catalog us Contributor us Code us_b000rx5i_mwb Principal Axes Axis Value Plunge Azimuth T 9.204 26 267 N 0.739 64 78 P -9.943 4 175 Nodal Planes Plane Strike Dip Rake NP1 44 75 21 NP2 308 69 164 |
July 25, 2014, SOUTHEASTERN ALASKA, MW=6.1 Meredith Nettles CENTROID-MOMENT-TENSOR SOLUTION GCMT EVENT: C201407251054B DATA: II IU DK MN G CU IC LD GE XF KP L.P.BODY WAVES:172S, 400C, T= 40 MANTLE WAVES: 145S, 222C, T=125 SURFACE WAVES: 186S, 467C, T= 50 TIMESTAMP: Q-20140725170628 CENTROID LOCATION: ORIGIN TIME: 10:54:54.6 0.1 LAT:58.44N 0.00;LON:137.03W 0.01 DEP: 12.0 FIX;TRIANG HDUR: 2.6 MOMENT TENSOR: SCALE 10**25 D-CM RR= 0.424 0.007; TT=-1.580 0.007 PP= 1.150 0.007; RT= 0.707 0.020 RP= 0.420 0.021; TP= 0.204 0.006 PRINCIPAL AXES: 1.(T) VAL= 1.426;PLG=29;AZM=281 2.(N) 0.374; 56; 64 3.(P) -1.806; 17; 181 BEST DBLE.COUPLE:M0= 1.62*10**25 NP1: STRIKE=318;DIP=57;SLIP= 171 NP2: STRIKE= 53;DIP=83;SLIP= 34 ----------- ------------------- #####------------------ ############--------------- ###############-----------### ###################-------##### ## ###############----####### ### T ################-########## ### ##############----######### ##################-------######## ###############-----------####### ############--------------##### #########-----------------##### #####---------------------### -------------------------## ---------- ---------- -------- P -------- ---- ---- |
(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 +60 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 1.0 55 85 -10 5.46 0.3200 WVFGRD96 2.0 55 80 -15 5.56 0.3957 WVFGRD96 3.0 55 80 -10 5.59 0.4282 WVFGRD96 4.0 55 85 20 5.63 0.4512 WVFGRD96 5.0 230 90 -20 5.65 0.4717 WVFGRD96 6.0 55 75 20 5.68 0.4948 WVFGRD96 7.0 55 75 15 5.70 0.5173 WVFGRD96 8.0 55 70 20 5.74 0.5401 WVFGRD96 9.0 55 70 20 5.76 0.5561 WVFGRD96 10.0 55 70 20 5.77 0.5693 WVFGRD96 11.0 55 70 20 5.78 0.5798 WVFGRD96 12.0 50 70 15 5.79 0.5884 WVFGRD96 13.0 50 70 15 5.80 0.5955 WVFGRD96 14.0 50 70 15 5.82 0.6008 WVFGRD96 15.0 50 75 15 5.83 0.6044 WVFGRD96 16.0 50 75 15 5.84 0.6068 WVFGRD96 17.0 50 75 15 5.85 0.6073 WVFGRD96 18.0 50 75 15 5.86 0.6062 WVFGRD96 19.0 50 75 15 5.87 0.6038 WVFGRD96 20.0 50 75 15 5.88 0.6002 WVFGRD96 21.0 50 75 15 5.89 0.5955 WVFGRD96 22.0 50 75 15 5.90 0.5895 WVFGRD96 23.0 50 75 15 5.91 0.5828 WVFGRD96 24.0 50 75 15 5.91 0.5754 WVFGRD96 25.0 50 75 10 5.92 0.5678 WVFGRD96 26.0 50 75 10 5.93 0.5596 WVFGRD96 27.0 50 75 -10 5.94 0.5525 WVFGRD96 28.0 50 75 -10 5.95 0.5448 WVFGRD96 29.0 50 75 -10 5.96 0.5368
The best solution is
WVFGRD96 17.0 50 75 15 5.85 0.6073
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 +60 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 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: