The ANSS event ID is ak015ddcgft7 and the event page is at https://earthquake.usgs.gov/earthquakes/eventpage/ak015ddcgft7/executive.
2015/10/18 05:15:30 62.776 -149.275 66.7 4.1 Kansas
USGS/SLU Moment Tensor Solution
ENS 2015/10/18 05:15:30:0 62.78 -149.27 66.7 4.1 Kansas
Stations used:
AK.BPAW AK.BWN AK.CCB AK.DHY AK.DOT AK.GHO AK.GLI AK.HDA
AK.KLU AK.KNK AK.KTH AK.MCK AK.MDM AK.MLY AK.NEA2 AK.RC01
AK.RIDG AK.RND AK.SAW AK.SCM AK.SKN AK.SSN AK.TRF AK.WRH
AT.PMR IU.COLA TA.K20K TA.N25K TA.TCOL
Filtering commands used:
cut o DIST/3.3 -30 o DIST/3.3 +50
rtr
taper w 0.1
hp c 0.02 n 3
lp c 0.10 n 3
Best Fitting Double Couple
Mo = 1.78e+22 dyne-cm
Mw = 4.10
Z = 76 km
Plane Strike Dip Rake
NP1 140 80 45
NP2 40 46 166
Principal Axes:
Axis Value Plunge Azimuth
T 1.78e+22 38 11
N 0.00e+00 44 150
P -1.78e+22 22 263
Moment Tensor: (dyne-cm)
Component Value
Mxx 1.04e+22
Mxy 3.27e+19
Mxz 9.27e+21
Myy -1.47e+22
Myz 7.65e+21
Mzz 4.30e+21
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---############# ##########-
-----############# T ##########---
-------############ ###########---
----------########################----
------------#######################-----
-------------#####################------
----------------###################-------
-----------------#################--------
--- ------------###############---------
--- P --------------############----------
-- ----------------#########----------
----------------------#######-----------
-----------------------###------------
-----------------------#------------
--------------------#####---------
---------------##########-----
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######################
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Global CMT Convention Moment Tensor:
R T P
4.30e+21 9.27e+21 -7.65e+21
9.27e+21 1.04e+22 -3.27e+19
-7.65e+21 -3.27e+19 -1.47e+22
Details of the solution is found at
http://www.eas.slu.edu/eqc/eqc_mt/MECH.NA/20151018051530/index.html
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STK = 140
DIP = 80
RAKE = 45
MW = 4.10
HS = 76.0
The NDK file is 20151018051530.ndk The waveform inversion is preferred.
Given the availability of digital waveforms for determination of the moment tensor, this section documents the added processing leading to mLg, if appropriate to the region, and ML by application of the respective IASPEI formulae. As a research study, the linear distance term of the IASPEI formula for ML is adjusted to remove a linear distance trend in residuals to give a regionally defined ML. The defined ML uses horizontal component recordings, but the same procedure is applied to the vertical components since there may be some interest in vertical component ground motions. Residual plots versus distance may indicate interesting features of ground motion scaling in some distance ranges. A residual plot of the regionalized magnitude is given as a function of distance and azimuth, since data sets may transcend different wave propagation provinces.
Left: ML computed using the IASPEI formula for Horizontal components. Center: 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.
Right: Residuals from new relation as a function of distance and azimuth.
Left: ML computed using the IASPEI formula for Vertical components (research). Center: 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.
Right: Residuals from new relation as a function of distance and azimuth.
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The focal mechanism was determined using broadband seismic waveforms. The location of the event (star) and the stations used for (red) 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's 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 +50 rtr taper w 0.1 hp c 0.02 n 3 lp c 0.10 n 3The results of this grid search are as follow:
DEPTH STK DIP RAKE MW FIT
WVFGRD96 2.0 260 50 60 3.16 0.1735
WVFGRD96 4.0 240 60 30 3.22 0.1960
WVFGRD96 6.0 50 70 -35 3.28 0.2267
WVFGRD96 8.0 225 60 -30 3.37 0.2512
WVFGRD96 10.0 245 70 40 3.42 0.2710
WVFGRD96 12.0 240 60 35 3.47 0.2876
WVFGRD96 14.0 240 60 35 3.50 0.2910
WVFGRD96 16.0 340 55 40 3.53 0.2836
WVFGRD96 18.0 340 55 40 3.57 0.2910
WVFGRD96 20.0 335 60 40 3.60 0.3006
WVFGRD96 22.0 335 60 40 3.64 0.3132
WVFGRD96 24.0 335 60 40 3.66 0.3259
WVFGRD96 26.0 335 60 40 3.68 0.3347
WVFGRD96 28.0 335 60 40 3.70 0.3390
WVFGRD96 30.0 335 60 40 3.71 0.3374
WVFGRD96 32.0 335 60 40 3.72 0.3292
WVFGRD96 34.0 135 70 -25 3.70 0.3298
WVFGRD96 36.0 135 65 -15 3.73 0.3358
WVFGRD96 38.0 135 60 -10 3.76 0.3471
WVFGRD96 40.0 135 50 -15 3.84 0.3640
WVFGRD96 42.0 315 75 -50 3.88 0.3668
WVFGRD96 44.0 140 90 50 3.93 0.3759
WVFGRD96 46.0 140 90 50 3.95 0.3945
WVFGRD96 48.0 140 90 50 3.97 0.4126
WVFGRD96 50.0 320 90 -50 3.98 0.4313
WVFGRD96 52.0 320 90 -50 4.00 0.4519
WVFGRD96 54.0 320 90 -55 4.02 0.4717
WVFGRD96 56.0 140 90 55 4.03 0.4891
WVFGRD96 58.0 140 85 50 4.04 0.5064
WVFGRD96 60.0 140 85 50 4.05 0.5213
WVFGRD96 62.0 140 85 50 4.06 0.5360
WVFGRD96 64.0 140 80 45 4.07 0.5473
WVFGRD96 66.0 140 80 50 4.09 0.5580
WVFGRD96 68.0 140 80 50 4.09 0.5657
WVFGRD96 70.0 140 80 50 4.10 0.5725
WVFGRD96 72.0 140 80 45 4.09 0.5749
WVFGRD96 74.0 140 80 45 4.10 0.5793
WVFGRD96 76.0 140 80 45 4.10 0.5802
WVFGRD96 78.0 140 80 45 4.10 0.5795
WVFGRD96 80.0 140 80 45 4.11 0.5791
WVFGRD96 82.0 145 70 40 4.12 0.5779
WVFGRD96 84.0 145 70 40 4.12 0.5764
WVFGRD96 86.0 145 70 40 4.12 0.5731
WVFGRD96 88.0 145 70 40 4.12 0.5704
WVFGRD96 90.0 145 65 40 4.14 0.5688
WVFGRD96 92.0 145 65 40 4.14 0.5673
WVFGRD96 94.0 145 65 40 4.14 0.5660
WVFGRD96 96.0 145 65 40 4.15 0.5643
WVFGRD96 98.0 145 65 40 4.15 0.5615
WVFGRD96 100.0 145 65 40 4.15 0.5581
WVFGRD96 102.0 145 65 40 4.15 0.5546
WVFGRD96 104.0 145 65 40 4.15 0.5503
WVFGRD96 106.0 145 65 40 4.15 0.5453
WVFGRD96 108.0 145 65 40 4.15 0.5404
WVFGRD96 110.0 145 65 40 4.16 0.5357
WVFGRD96 112.0 145 65 40 4.16 0.5307
WVFGRD96 114.0 145 65 35 4.15 0.5255
WVFGRD96 116.0 145 65 35 4.15 0.5194
WVFGRD96 118.0 310 85 -30 4.10 0.5142
WVFGRD96 2.0 260 50 60 3.16 0.1799
WVFGRD96 4.0 240 60 30 3.22 0.2024
WVFGRD96 6.0 50 70 -35 3.28 0.2339
WVFGRD96 8.0 225 60 -30 3.37 0.2592
WVFGRD96 10.0 245 70 40 3.42 0.2798
WVFGRD96 12.0 240 60 35 3.47 0.2971
WVFGRD96 14.0 240 60 35 3.50 0.3006
WVFGRD96 16.0 340 55 40 3.53 0.2929
WVFGRD96 18.0 340 55 40 3.57 0.3005
WVFGRD96 20.0 335 60 40 3.60 0.3104
WVFGRD96 22.0 335 60 40 3.64 0.3236
WVFGRD96 24.0 335 60 40 3.66 0.3367
WVFGRD96 26.0 335 60 40 3.68 0.3459
WVFGRD96 28.0 335 60 40 3.70 0.3503
WVFGRD96 30.0 335 60 40 3.71 0.3487
WVFGRD96 32.0 335 60 40 3.72 0.3402
WVFGRD96 34.0 135 70 -25 3.70 0.3401
WVFGRD96 36.0 135 65 -15 3.73 0.3462
WVFGRD96 38.0 135 60 -10 3.76 0.3578
WVFGRD96 40.0 135 50 -15 3.84 0.3753
WVFGRD96 42.0 315 75 -50 3.88 0.3781
WVFGRD96 44.0 140 90 50 3.92 0.3875
WVFGRD96 46.0 140 90 50 3.95 0.4067
WVFGRD96 48.0 140 90 50 3.97 0.4253
WVFGRD96 50.0 140 90 50 3.98 0.4446
WVFGRD96 52.0 320 90 -50 4.00 0.4659
WVFGRD96 54.0 140 90 55 4.02 0.4863
WVFGRD96 56.0 140 90 55 4.03 0.5043
WVFGRD96 58.0 140 85 50 4.04 0.5222
WVFGRD96 60.0 140 85 50 4.05 0.5377
WVFGRD96 62.0 140 85 50 4.06 0.5528
WVFGRD96 64.0 140 80 45 4.07 0.5646
WVFGRD96 66.0 140 80 50 4.09 0.5756
WVFGRD96 68.0 140 80 50 4.09 0.5836
WVFGRD96 70.0 140 80 50 4.10 0.5906
WVFGRD96 72.0 140 80 45 4.09 0.5931
WVFGRD96 74.0 140 80 45 4.10 0.5977
WVFGRD96 76.0 140 80 45 4.10 0.5984
WVFGRD96 78.0 140 80 45 4.10 0.5977
WVFGRD96 80.0 140 80 45 4.11 0.5974
WVFGRD96 82.0 145 70 40 4.12 0.5961
WVFGRD96 84.0 145 70 40 4.12 0.5947
WVFGRD96 86.0 145 70 40 4.12 0.5912
WVFGRD96 88.0 145 70 40 4.12 0.5885
WVFGRD96 90.0 145 65 40 4.14 0.5868
WVFGRD96 92.0 145 65 40 4.14 0.5853
WVFGRD96 94.0 145 65 40 4.14 0.5840
WVFGRD96 96.0 145 65 40 4.15 0.5822
WVFGRD96 98.0 145 65 40 4.15 0.5794
WVFGRD96 100.0 145 65 40 4.15 0.5759
WVFGRD96 102.0 145 65 40 4.15 0.5723
WVFGRD96 104.0 145 65 40 4.15 0.5679
WVFGRD96 106.0 145 65 40 4.15 0.5627
WVFGRD96 108.0 145 65 40 4.15 0.5577
WVFGRD96 110.0 145 65 40 4.16 0.5528
WVFGRD96 112.0 145 65 40 4.16 0.5477
WVFGRD96 114.0 145 65 35 4.15 0.5422
WVFGRD96 116.0 145 65 35 4.15 0.5360
WVFGRD96 118.0 310 85 -30 4.10 0.5306
WVFGRD96 2.0 260 50 60 3.16 0.1799
WVFGRD96 4.0 240 60 30 3.22 0.2024
WVFGRD96 6.0 50 70 -35 3.28 0.2339
WVFGRD96 8.0 225 60 -30 3.37 0.2592
WVFGRD96 10.0 245 70 40 3.42 0.2798
WVFGRD96 12.0 240 60 35 3.47 0.2971
WVFGRD96 14.0 240 60 35 3.50 0.3006
WVFGRD96 16.0 340 55 40 3.53 0.2929
WVFGRD96 18.0 340 55 40 3.57 0.3005
WVFGRD96 20.0 335 60 40 3.60 0.3104
WVFGRD96 22.0 335 60 40 3.64 0.3236
WVFGRD96 24.0 335 60 40 3.66 0.3367
WVFGRD96 26.0 335 60 40 3.68 0.3459
WVFGRD96 28.0 335 60 40 3.70 0.3503
WVFGRD96 30.0 335 60 40 3.71 0.3487
WVFGRD96 32.0 335 60 40 3.72 0.3402
WVFGRD96 34.0 135 70 -25 3.70 0.3401
WVFGRD96 36.0 135 65 -15 3.73 0.3462
WVFGRD96 38.0 135 60 -10 3.76 0.3578
WVFGRD96 40.0 135 50 -15 3.84 0.3753
WVFGRD96 42.0 315 75 -50 3.88 0.3781
WVFGRD96 44.0 140 90 50 3.92 0.3875
WVFGRD96 46.0 140 90 50 3.95 0.4067
WVFGRD96 48.0 140 90 50 3.97 0.4253
WVFGRD96 50.0 140 90 50 3.98 0.4446
WVFGRD96 52.0 320 90 -50 4.00 0.4659
WVFGRD96 54.0 140 90 55 4.02 0.4863
WVFGRD96 56.0 140 90 55 4.03 0.5043
WVFGRD96 58.0 140 85 50 4.04 0.5222
WVFGRD96 60.0 140 85 50 4.05 0.5377
WVFGRD96 62.0 140 85 50 4.06 0.5528
WVFGRD96 64.0 140 80 45 4.07 0.5646
WVFGRD96 66.0 140 80 50 4.09 0.5756
WVFGRD96 68.0 140 80 50 4.09 0.5836
WVFGRD96 70.0 140 80 50 4.10 0.5906
WVFGRD96 72.0 140 80 45 4.09 0.5931
WVFGRD96 74.0 140 80 45 4.10 0.5977
WVFGRD96 76.0 140 80 45 4.10 0.5984
WVFGRD96 78.0 140 80 45 4.10 0.5977
WVFGRD96 80.0 140 80 45 4.11 0.5974
WVFGRD96 82.0 145 70 40 4.12 0.5961
WVFGRD96 84.0 145 70 40 4.12 0.5947
WVFGRD96 86.0 145 70 40 4.12 0.5912
WVFGRD96 88.0 145 70 40 4.12 0.5885
WVFGRD96 90.0 145 65 40 4.14 0.5868
WVFGRD96 92.0 145 65 40 4.14 0.5853
WVFGRD96 94.0 145 65 40 4.14 0.5840
WVFGRD96 96.0 145 65 40 4.15 0.5822
WVFGRD96 98.0 145 65 40 4.15 0.5794
WVFGRD96 100.0 145 65 40 4.15 0.5759
WVFGRD96 102.0 145 65 40 4.15 0.5723
WVFGRD96 104.0 145 65 40 4.15 0.5679
WVFGRD96 106.0 145 65 40 4.15 0.5627
WVFGRD96 108.0 145 65 40 4.15 0.5577
WVFGRD96 110.0 145 65 40 4.16 0.5528
WVFGRD96 112.0 145 65 40 4.16 0.5477
WVFGRD96 114.0 145 65 35 4.15 0.5422
WVFGRD96 116.0 145 65 35 4.15 0.5360
WVFGRD96 118.0 310 85 -30 4.10 0.5306
WVFGRD96 2.0 260 50 60 3.16 0.1799
WVFGRD96 4.0 240 60 30 3.22 0.2024
WVFGRD96 6.0 50 70 -35 3.28 0.2339
WVFGRD96 8.0 225 60 -30 3.37 0.2592
WVFGRD96 10.0 245 70 40 3.42 0.2798
WVFGRD96 12.0 240 60 35 3.47 0.2971
WVFGRD96 14.0 240 60 35 3.50 0.3006
WVFGRD96 16.0 340 55 40 3.53 0.2929
WVFGRD96 18.0 340 55 40 3.57 0.3005
WVFGRD96 20.0 335 60 40 3.60 0.3104
WVFGRD96 22.0 335 60 40 3.64 0.3236
WVFGRD96 24.0 335 60 40 3.66 0.3367
WVFGRD96 26.0 335 60 40 3.68 0.3459
WVFGRD96 28.0 335 60 40 3.70 0.3503
WVFGRD96 30.0 335 60 40 3.71 0.3487
WVFGRD96 32.0 335 60 40 3.72 0.3402
WVFGRD96 34.0 135 70 -25 3.70 0.3401
WVFGRD96 36.0 135 65 -15 3.73 0.3462
WVFGRD96 38.0 135 60 -10 3.76 0.3578
WVFGRD96 40.0 135 50 -15 3.84 0.3753
WVFGRD96 42.0 315 75 -50 3.88 0.3781
WVFGRD96 44.0 140 90 50 3.92 0.3875
WVFGRD96 46.0 140 90 50 3.95 0.4067
WVFGRD96 48.0 140 90 50 3.97 0.4253
WVFGRD96 50.0 140 90 50 3.98 0.4446
WVFGRD96 52.0 320 90 -50 4.00 0.4659
WVFGRD96 54.0 140 90 55 4.02 0.4863
WVFGRD96 56.0 140 90 55 4.03 0.5043
WVFGRD96 58.0 140 85 50 4.04 0.5222
WVFGRD96 60.0 140 85 50 4.05 0.5377
WVFGRD96 62.0 140 85 50 4.06 0.5528
WVFGRD96 64.0 140 80 45 4.07 0.5646
WVFGRD96 66.0 140 80 50 4.09 0.5756
WVFGRD96 68.0 140 80 50 4.09 0.5836
WVFGRD96 70.0 140 80 50 4.10 0.5906
WVFGRD96 72.0 140 80 45 4.09 0.5931
WVFGRD96 74.0 140 80 45 4.10 0.5977
WVFGRD96 76.0 140 80 45 4.10 0.5984
WVFGRD96 78.0 140 80 45 4.10 0.5977
WVFGRD96 80.0 140 80 45 4.11 0.5974
WVFGRD96 82.0 145 70 40 4.12 0.5961
WVFGRD96 84.0 145 70 40 4.12 0.5947
WVFGRD96 86.0 145 70 40 4.12 0.5912
WVFGRD96 88.0 145 70 40 4.12 0.5885
WVFGRD96 90.0 145 65 40 4.14 0.5868
WVFGRD96 92.0 145 65 40 4.14 0.5853
WVFGRD96 94.0 145 65 40 4.14 0.5840
WVFGRD96 96.0 145 65 40 4.15 0.5822
WVFGRD96 98.0 145 65 40 4.15 0.5794
WVFGRD96 100.0 145 65 40 4.15 0.5759
WVFGRD96 102.0 145 65 40 4.15 0.5723
WVFGRD96 104.0 145 65 40 4.15 0.5679
WVFGRD96 106.0 145 65 40 4.15 0.5627
WVFGRD96 108.0 145 65 40 4.15 0.5577
WVFGRD96 110.0 145 65 40 4.16 0.5528
WVFGRD96 112.0 145 65 40 4.16 0.5477
WVFGRD96 114.0 145 65 35 4.15 0.5422
WVFGRD96 116.0 145 65 35 4.15 0.5360
WVFGRD96 118.0 310 85 -30 4.10 0.5306
The best solution is
WVFGRD96 76.0 140 80 45 4.10 0.5984
The mechanism corresponding 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, the velocity model used in the predictions may not be perfect and the epicentral parameters may be be off. 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 +50 rtr taper w 0.1 hp c 0.02 n 3 lp c 0.10 n 3
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| Figure 3. Waveform comparison for selected depth. Red: observed; Blue - predicted. The time shift with respect to the model prediction is indicated. The percent of fit is also indicated. The time scale is relative to the first trace sample. |
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| Focal mechanism sensitivity at the preferred depth. The red color indicates a very good fit to the waveforms. 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.
The WUS.model used for the waveform synthetic seismograms and for the surface wave eigenfunctions and dispersion is as follows (The format is in the model96 format of Computer Programs in Seismology).
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