2011/06/07 08:10:34 38.4121 -90.933 5 4.20 Missouri
USGS Felt map for this earthquake
USGS/SLU Moment Tensor Solution ENS 2011/06/07 08:10:34:0 38.41 -90.93 5.0 4.2 Missouri Stations used: IU.WCI IU.WVT NM.BLO NM.MGMO NM.MPH NM.OLIL NM.PBMO NM.PVMO NM.SIUC NM.SLM NM.UALR NM.USIN NM.UTMT NM.X201 NM.X301 TA.N37A TA.N39A TA.O38A TA.O40A TA.P36A TA.P37A TA.P38A TA.P40A TA.Q36A TA.Q38A TA.Q39A TA.Q40A TA.R36A TA.R37A TA.R38A TA.R39A TA.S37A TA.S38A TA.S39A TA.S40A TA.SFIN TA.T37A TA.T38A TA.T39A TA.T40A TA.U38A TA.U39A TA.U40A TA.V37A TA.W39A TA.W40A TA.X40A US.HDIL Filtering commands used: hp c 0.02 n 3 lp c 0.10 n 3 Best Fitting Double Couple Mo = 7.76e+21 dyne-cm Mw = 3.86 Z = 27 km Plane Strike Dip Rake NP1 100 80 25 NP2 5 65 169 Principal Axes: Axis Value Plunge Azimuth T 7.76e+21 25 325 N 0.00e+00 63 120 P -7.76e+21 10 231 Moment Tensor: (dyne-cm) Component Value Mxx 1.28e+21 Mxy -6.70e+21 Mxz 3.25e+21 Myy -2.40e+21 Myz -6.68e+20 Mzz 1.12e+21 ##########---- ###############------- ### #############--------- #### T #############---------- ###### ##############----------- ########################------------ #########################------------- ##########################-------------- ##########################-------------- --#########################--------------- -------####################--------------- -------------##############--------------- ----------------------#####--------------- --------------------------############## -------------------------############### ------------------------############## -- -----------------############## - P -----------------############# ----------------############ ----------------############ ------------########## ------######## Global CMT Convention Moment Tensor: R T P 1.12e+21 3.25e+21 6.68e+20 3.25e+21 1.28e+21 6.70e+21 6.68e+20 6.70e+21 -2.40e+21 Details of the solution is found at http://www.eas.slu.edu/eqc/eqc_mt/MECH.NA/20110607081034/index.html |
STK = 100 DIP = 80 RAKE = 25 MW = 3.86 HS = 27.0
The NDK file is 20110607081034.ndk The waveform inversion is preferred.
The following compares this source inversion to others
USGS/SLU Moment Tensor Solution ENS 2011/06/07 08:10:34:0 38.41 -90.93 5.0 4.2 Missouri Stations used: IU.WCI IU.WVT NM.BLO NM.MGMO NM.MPH NM.OLIL NM.PBMO NM.PVMO NM.SIUC NM.SLM NM.UALR NM.USIN NM.UTMT NM.X201 NM.X301 TA.N37A TA.N39A TA.O38A TA.O40A TA.P36A TA.P37A TA.P38A TA.P40A TA.Q36A TA.Q38A TA.Q39A TA.Q40A TA.R36A TA.R37A TA.R38A TA.R39A TA.S37A TA.S38A TA.S39A TA.S40A TA.SFIN TA.T37A TA.T38A TA.T39A TA.T40A TA.U38A TA.U39A TA.U40A TA.V37A TA.W39A TA.W40A TA.X40A US.HDIL Filtering commands used: hp c 0.02 n 3 lp c 0.10 n 3 Best Fitting Double Couple Mo = 7.76e+21 dyne-cm Mw = 3.86 Z = 27 km Plane Strike Dip Rake NP1 100 80 25 NP2 5 65 169 Principal Axes: Axis Value Plunge Azimuth T 7.76e+21 25 325 N 0.00e+00 63 120 P -7.76e+21 10 231 Moment Tensor: (dyne-cm) Component Value Mxx 1.28e+21 Mxy -6.70e+21 Mxz 3.25e+21 Myy -2.40e+21 Myz -6.68e+20 Mzz 1.12e+21 ##########---- ###############------- ### #############--------- #### T #############---------- ###### ##############----------- ########################------------ #########################------------- ##########################-------------- ##########################-------------- --#########################--------------- -------####################--------------- -------------##############--------------- ----------------------#####--------------- --------------------------############## -------------------------############### ------------------------############## -- -----------------############## - P -----------------############# ----------------############ ----------------############ ------------########## ------######## Global CMT Convention Moment Tensor: R T P 1.12e+21 3.25e+21 6.68e+20 3.25e+21 1.28e+21 6.70e+21 6.68e+20 6.70e+21 -2.40e+21 Details of the solution is found at http://www.eas.slu.edu/eqc/eqc_mt/MECH.NA/20110607081034/index.html |
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(a) mLg computed using the IASPEI formula; (b) mLg residuals ; the values used for the trimmed mean are indicated.
(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 0.10 n 3The results of this grid search from 0.5 to 19 km depth are as follow:
DEPTH STK DIP RAKE MW FIT WVFGRD96 0.5 100 90 5 3.40 0.3398 WVFGRD96 1.0 280 90 -5 3.44 0.3718 WVFGRD96 2.0 280 90 0 3.50 0.4212 WVFGRD96 3.0 100 85 0 3.54 0.4344 WVFGRD96 4.0 100 90 -10 3.56 0.4262 WVFGRD96 5.0 280 90 -20 3.57 0.4206 WVFGRD96 6.0 100 85 20 3.59 0.4258 WVFGRD96 7.0 100 85 20 3.60 0.4323 WVFGRD96 8.0 100 80 20 3.61 0.4414 WVFGRD96 9.0 100 85 20 3.62 0.4524 WVFGRD96 10.0 100 80 20 3.65 0.4661 WVFGRD96 11.0 100 75 20 3.66 0.4794 WVFGRD96 12.0 100 75 20 3.68 0.4910 WVFGRD96 13.0 100 80 20 3.69 0.5008 WVFGRD96 14.0 100 80 20 3.70 0.5089 WVFGRD96 15.0 100 80 20 3.72 0.5153 WVFGRD96 16.0 100 80 20 3.73 0.5207 WVFGRD96 17.0 100 80 20 3.74 0.5248 WVFGRD96 18.0 100 80 20 3.75 0.5291 WVFGRD96 19.0 100 80 20 3.77 0.5332 WVFGRD96 20.0 100 80 25 3.79 0.5381 WVFGRD96 21.0 100 80 25 3.80 0.5425 WVFGRD96 22.0 100 80 25 3.81 0.5464 WVFGRD96 23.0 100 80 25 3.82 0.5500 WVFGRD96 24.0 100 80 25 3.83 0.5541 WVFGRD96 25.0 100 80 25 3.84 0.5566 WVFGRD96 26.0 100 80 25 3.85 0.5576 WVFGRD96 27.0 100 80 25 3.86 0.5578 WVFGRD96 28.0 100 80 25 3.87 0.5564 WVFGRD96 29.0 100 80 25 3.88 0.5527 WVFGRD96 30.0 100 80 30 3.89 0.5483 WVFGRD96 31.0 100 80 30 3.90 0.5428 WVFGRD96 32.0 100 80 30 3.91 0.5351 WVFGRD96 33.0 100 80 30 3.92 0.5261 WVFGRD96 34.0 100 80 30 3.93 0.5167 WVFGRD96 35.0 100 80 30 3.94 0.5066 WVFGRD96 36.0 100 80 30 3.95 0.4960 WVFGRD96 37.0 100 80 30 3.96 0.4861 WVFGRD96 38.0 100 80 30 3.97 0.4766 WVFGRD96 39.0 100 85 25 3.99 0.4680
The best solution is
WVFGRD96 27.0 100 80 25 3.86 0.5578
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 0.10 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: