USGS/SLU Moment Tensor Solution ENS 2018/06/10 10:51:02:0 19.41 -155.28 1.8 5.3 Hawaii Stations used: HV.ERZ1 HV.ERZ2 HV.ERZ3 HV.ERZ4 HV.HLPD HV.HOVE HV.HSSD HV.HUAD HV.JOKA HV.MLOD HV.MOKD HV.NPOC HV.PHOD HV.STCD HV.TOUO IU.POHA PT.HPAH PT.MLOA Filtering commands used: cut o DIST/3.3 -30 o DIST/3.3 +70 rtr taper w 0.1 hp c 0.02 n 3 lp c 0.05 n 3 Best Fitting Double Couple Mo = 4.27e+23 dyne-cm Mw = 5.02 Z = 3 km Plane Strike Dip Rake NP1 25 50 -100 NP2 220 41 -78 Principal Axes: Axis Value Plunge Azimuth T 4.27e+23 5 122 N 0.00e+00 8 31 P -4.27e+23 81 242 Moment Tensor: (dyne-cm) Component Value Mxx 1.17e+23 Mxy -1.95e+23 Mxz 1.23e+22 Myy 2.96e+23 Myz 8.62e+22 Mzz -4.14e+23 ############## #####################- ################--------#### #############-------------#### ############-----------------##### ###########-------------------###### ##########---------------------####### ##########----------------------######## ########------------------------######## ########------------------------########## #######----------- -----------########## #######----------- P ----------########### ######------------ ----------########### #####------------------------########### #####-----------------------############ ####----------------------######## # ###--------------------########## T ##-------------------########### #----------------############# #-------------############## -------############### ############## Global CMT Convention Moment Tensor: R T P -4.14e+23 1.23e+22 -8.62e+22 1.23e+22 1.17e+23 1.95e+23 -8.62e+22 1.95e+23 2.96e+23 Details of the solution is found at http://www.eas.slu.edu/eqc/eqc_mt/MECH.NA/20180610105102/index.html |
STK = 25 DIP = 50 RAKE = -100 MW = 5.02 HS = 3.0
The NDK file is 20180610105102.ndk The waveform inversion is preferred.
The following compares this source inversion to others
USGS/SLU Moment Tensor Solution ENS 2018/06/10 10:51:02:0 19.41 -155.28 1.8 5.3 Hawaii Stations used: HV.ERZ1 HV.ERZ2 HV.ERZ3 HV.ERZ4 HV.HLPD HV.HOVE HV.HSSD HV.HUAD HV.JOKA HV.MLOD HV.MOKD HV.NPOC HV.PHOD HV.STCD HV.TOUO IU.POHA PT.HPAH PT.MLOA Filtering commands used: cut o DIST/3.3 -30 o DIST/3.3 +70 rtr taper w 0.1 hp c 0.02 n 3 lp c 0.05 n 3 Best Fitting Double Couple Mo = 4.27e+23 dyne-cm Mw = 5.02 Z = 3 km Plane Strike Dip Rake NP1 25 50 -100 NP2 220 41 -78 Principal Axes: Axis Value Plunge Azimuth T 4.27e+23 5 122 N 0.00e+00 8 31 P -4.27e+23 81 242 Moment Tensor: (dyne-cm) Component Value Mxx 1.17e+23 Mxy -1.95e+23 Mxz 1.23e+22 Myy 2.96e+23 Myz 8.62e+22 Mzz -4.14e+23 ############## #####################- ################--------#### #############-------------#### ############-----------------##### ###########-------------------###### ##########---------------------####### ##########----------------------######## ########------------------------######## ########------------------------########## #######----------- -----------########## #######----------- P ----------########### ######------------ ----------########### #####------------------------########### #####-----------------------############ ####----------------------######## # ###--------------------########## T ##-------------------########### #----------------############# #-------------############## -------############### ############## Global CMT Convention Moment Tensor: R T P -4.14e+23 1.23e+22 -8.62e+22 1.23e+22 1.17e+23 1.95e+23 -8.62e+22 1.95e+23 2.96e+23 Details of the solution is found at http://www.eas.slu.edu/eqc/eqc_mt/MECH.NA/20180610105102/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:
cut o DIST/3.3 -30 o DIST/3.3 +70 rtr taper w 0.1 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 1.0 35 45 -85 4.88 0.4719 WVFGRD96 2.0 40 45 -80 4.97 0.5723 WVFGRD96 3.0 25 50 -100 5.02 0.5921 WVFGRD96 4.0 40 50 -80 5.04 0.5814 WVFGRD96 5.0 55 55 -55 5.04 0.5777 WVFGRD96 6.0 60 60 -45 5.05 0.5660 WVFGRD96 7.0 75 65 -25 5.05 0.5557 WVFGRD96 8.0 60 55 -50 5.12 0.5644 WVFGRD96 9.0 75 65 -20 5.10 0.5480 WVFGRD96 10.0 75 70 -15 5.10 0.5332 WVFGRD96 11.0 75 70 -15 5.11 0.5172 WVFGRD96 12.0 75 75 -10 5.12 0.5008 WVFGRD96 13.0 75 75 -10 5.13 0.4857 WVFGRD96 14.0 75 75 -10 5.14 0.4710 WVFGRD96 15.0 75 75 -10 5.15 0.4555 WVFGRD96 16.0 75 75 -10 5.15 0.4401 WVFGRD96 17.0 75 75 -10 5.16 0.4251 WVFGRD96 18.0 290 60 75 5.17 0.4120 WVFGRD96 19.0 290 60 75 5.17 0.4042 WVFGRD96 20.0 290 55 75 5.16 0.3970 WVFGRD96 21.0 290 55 75 5.17 0.3885 WVFGRD96 22.0 290 55 75 5.17 0.3816 WVFGRD96 23.0 285 55 70 5.17 0.3744 WVFGRD96 24.0 290 50 75 5.17 0.3683 WVFGRD96 25.0 290 50 75 5.17 0.3621 WVFGRD96 26.0 290 50 70 5.17 0.3567 WVFGRD96 27.0 290 50 70 5.17 0.3514 WVFGRD96 28.0 290 50 70 5.17 0.3462 WVFGRD96 29.0 285 50 65 5.17 0.3412
The best solution is
WVFGRD96 3.0 25 50 -100 5.02 0.5921
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 +70 rtr taper w 0.1 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.
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.
|
The program wvfmtgrd96 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 -20 o DIST/3.3 +50 rtr taper w 0.1 hp c 0.02 n 3 lp c 0.05 n 3The results of this grid search over depth are as follow:
MT Program H(km) Mxx(dyne-cm) Myy Mxy Mxz Myz Mzz Mw Fit WVFMTGRD96 1.0 0.131E+24 0.234E+24 -0.116E+24 -0.152E+23 -0.136E+23 -0.105E+24 4.8481 0.4807 WVFMTGRD96 2.0 0.938E+23 0.244E+24 -0.169E+24 -0.342E+23 -0.287E+23 -0.369E+24 4.9743 0.5715 WVFMTGRD96 3.0 0.191E+24 0.364E+24 -0.197E+24 -0.146E+23 0.579E+23 -0.100E+24 4.9732 0.6065 WVFMTGRD96 4.0 0.284E+24 0.450E+24 -0.216E+24 0.462E+22 0.462E+23 0.703E+23 5.0282 0.6218 WVFMTGRD96 5.0 0.287E+24 0.502E+24 -0.240E+24 -0.270E+23 0.417E+23 0.136E+24 5.0577 0.6315 WVFMTGRD96 6.0 0.323E+24 0.559E+24 -0.263E+24 -0.309E+23 0.415E+23 0.187E+24 5.0913 0.6389 WVFMTGRD96 7.0 0.360E+24 0.622E+24 -0.293E+24 -0.224E+23 0.429E+23 0.206E+24 5.1216 0.6462 WVFMTGRD96 8.0 0.472E+24 0.729E+24 -0.323E+24 -0.398E+23 0.259E+23 0.298E+24 5.1742 0.6534 WVFMTGRD96 9.0 0.541E+24 0.809E+24 -0.350E+24 -0.137E+23 0.471E+23 0.376E+24 5.2084 0.6514 WVFMTGRD96 10.0 0.578E+24 0.860E+24 -0.388E+24 -0.297E+16 -0.261E+17 0.494E+24 5.2360 0.6459 WVFMTGRD96 11.0 0.614E+24 0.903E+24 -0.398E+24 -0.344E+23 0.179E+23 0.626E+24 5.2595 0.6376 WVFMTGRD96 12.0 0.728E+24 0.102E+25 -0.407E+24 0.311E+23 0.221E+23 0.744E+24 5.2962 0.6262 WVFMTGRD96 13.0 0.899E+24 0.105E+25 -0.443E+24 0.381E+23 -0.158E+23 0.835E+24 5.3260 0.6127 WVFMTGRD96 14.0 0.942E+24 0.110E+25 -0.442E+24 0.144E+17 0.340E+17 0.926E+24 5.3410 0.5985 WVFMTGRD96 15.0 0.968E+24 0.113E+25 -0.461E+24 0.180E+17 0.366E+17 0.984E+24 5.3520 0.5836 WVFMTGRD96 16.0 0.104E+25 0.120E+25 -0.455E+24 0.193E+17 0.368E+17 0.107E+25 5.3701 0.5677 WVFMTGRD96 17.0 0.106E+25 0.122E+25 -0.469E+24 0.229E+17 0.390E+17 0.112E+25 5.3780 0.5518 WVFMTGRD96 18.0 0.111E+25 0.128E+25 -0.489E+24 0.432E+23 -0.528E+22 0.118E+25 5.3914 0.5368 WVFMTGRD96 19.0 0.109E+25 0.126E+25 -0.491E+24 0.286E+17 0.428E+17 0.121E+25 5.3915 0.5214 WVFMTGRD96 20.0 0.111E+25 0.128E+25 -0.491E+24 -0.318E+17 -0.440E+17 0.127E+25 5.3983 0.5071 WVFMTGRD96 21.0 0.114E+25 0.132E+25 -0.510E+24 0.381E+17 0.477E+17 0.136E+25 5.4113 0.4939 WVFMTGRD96 22.0 0.115E+25 0.133E+25 -0.513E+24 0.416E+17 0.493E+17 0.140E+25 5.4146 0.4805 WVFMTGRD96 23.0 0.110E+25 0.129E+25 -0.531E+24 0.467E+17 0.525E+17 0.140E+25 5.4101 0.4676 WVFMTGRD96 24.0 0.110E+25 0.129E+25 -0.535E+24 -0.489E+17 -0.536E+17 0.143E+25 5.4134 0.4560 WVFMTGRD96 25.0 0.110E+25 0.128E+25 -0.531E+24 0.523E+17 0.547E+17 0.146E+25 5.4145 0.4445 WVFMTGRD96 26.0 0.113E+25 0.132E+25 -0.543E+24 0.502E+23 0.200E+23 0.150E+25 5.4223 0.4344 WVFMTGRD96 27.0 0.114E+25 0.134E+25 -0.550E+24 0.508E+23 0.202E+23 0.152E+25 5.4259 0.4244 WVFMTGRD96 28.0 0.130E+25 0.129E+25 -0.585E+24 0.293E+23 -0.288E+23 0.155E+25 5.4363 0.4156 WVFMTGRD96 29.0 0.138E+25 0.136E+25 -0.573E+24 0.792E+23 -0.536E+22 0.163E+25 5.4499 0.4077
The best solution is
WVFMTGRD96 8.0 0.472E+24 0.729E+24 -0.323E+24 -0.398E+23 0.259E+23 0.298E+24 5.1742 0.6534
The complete moment tensor decomposition using the program mtinfo is given in the text file MTGRDinfo.txt. (Jost, M. L., and R. B. Herrmann (1989). A student's guide to and review of moment tensors, Seism. Res. Letters 60, 37-57. SRL_60_2_37-57.pdf.
The P-wave first motion 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 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 -20 o DIST/3.3 +50 rtr taper w 0.1 hp c 0.02 n 3 lp c 0.05 n 3
|
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: