2013/09/14 10:25:34 32.273 -115.165 12.4 4.1 Mexico
USGS Felt map for this earthquake
USGS/SLU Moment Tensor Solution ENS 2013/09/14 10:25:34:0 32.27 -115.17 12.4 4.1 Mexico Stations used: AE.W13A AZ.BZN AZ.CPE AZ.CRY AZ.FRD AZ.KNW AZ.LVA2 AZ.MONP2 AZ.RDM AZ.RRSP AZ.SMER AZ.SND AZ.SOL AZ.TMSP AZ.WMC CI.ADO CI.ARV CI.BAR CI.BFS CI.CHF CI.CIA CI.CWC CI.DEC CI.DGR CI.DJJ CI.EDW2 CI.FMP CI.IKP CI.LGU CI.LRL CI.MPP CI.MUR CI.MWC CI.NEE2 CI.OSI CI.PASC CI.PDM CI.PHL CI.PLM CI.RPV CI.RRX CI.SCI2 CI.SDD CI.SMM CI.SNCC CI.SVD CI.SWS CI.USC CI.VCS CI.VES CI.VOG CI.VTV II.PFO IU.TUC NN.SHP PB.B082A PB.B086A TA.109C TA.TPFO TA.Y12C US.TPNV UU.LCMT UU.VRUT Filtering commands used: cut a -30 a 210 rtr taper w 0.1 hp c 0.02 n 3 lp c 0.04 n 3 br c 0.12 0.25 n 4 p 2 Best Fitting Double Couple Mo = 1.78e+22 dyne-cm Mw = 4.10 Z = 9 km Plane Strike Dip Rake NP1 45 75 -95 NP2 244 16 -72 Principal Axes: Axis Value Plunge Azimuth T 1.78e+22 30 139 N 0.00e+00 5 46 P -1.78e+22 60 308 Moment Tensor: (dyne-cm) Component Value Mxx 5.93e+21 Mxy -4.43e+21 Mxz -1.06e+22 Myy 2.93e+21 Myz 1.11e+22 Mzz -8.86e+21 ############## ########---------##### ######-------------------### ####-------------------------- ####---------------------------##- ###----------------------------##### ###----------------------------####### ###--------- ---------------########## ##---------- P --------------########### ##----------- -------------############# ##-------------------------############### #------------------------################# #-----------------------################## ---------------------################### #------------------##################### ---------------####################### ------------############## ####### --------################# T ###### ---#################### #### ############################ ###################### ############## Global CMT Convention Moment Tensor: R T P -8.86e+21 -1.06e+22 -1.11e+22 -1.06e+22 5.93e+21 4.43e+21 -1.11e+22 4.43e+21 2.93e+21 Details of the solution is found at http://www.eas.slu.edu/eqc/eqc_mt/MECH.NA/20130914102534/index.html |
STK = 45 DIP = 75 RAKE = -95 MW = 4.10 HS = 9.0
The NDK file is 20130914102534.ndk The waveform inversion is preferred.
The following compares this source inversion to others
USGS/SLU Moment Tensor Solution ENS 2013/09/14 10:25:34:0 32.27 -115.17 12.4 4.1 Mexico Stations used: AE.W13A AZ.BZN AZ.CPE AZ.CRY AZ.FRD AZ.KNW AZ.LVA2 AZ.MONP2 AZ.RDM AZ.RRSP AZ.SMER AZ.SND AZ.SOL AZ.TMSP AZ.WMC CI.ADO CI.ARV CI.BAR CI.BFS CI.CHF CI.CIA CI.CWC CI.DEC CI.DGR CI.DJJ CI.EDW2 CI.FMP CI.IKP CI.LGU CI.LRL CI.MPP CI.MUR CI.MWC CI.NEE2 CI.OSI CI.PASC CI.PDM CI.PHL CI.PLM CI.RPV CI.RRX CI.SCI2 CI.SDD CI.SMM CI.SNCC CI.SVD CI.SWS CI.USC CI.VCS CI.VES CI.VOG CI.VTV II.PFO IU.TUC NN.SHP PB.B082A PB.B086A TA.109C TA.TPFO TA.Y12C US.TPNV UU.LCMT UU.VRUT Filtering commands used: cut a -30 a 210 rtr taper w 0.1 hp c 0.02 n 3 lp c 0.04 n 3 br c 0.12 0.25 n 4 p 2 Best Fitting Double Couple Mo = 1.78e+22 dyne-cm Mw = 4.10 Z = 9 km Plane Strike Dip Rake NP1 45 75 -95 NP2 244 16 -72 Principal Axes: Axis Value Plunge Azimuth T 1.78e+22 30 139 N 0.00e+00 5 46 P -1.78e+22 60 308 Moment Tensor: (dyne-cm) Component Value Mxx 5.93e+21 Mxy -4.43e+21 Mxz -1.06e+22 Myy 2.93e+21 Myz 1.11e+22 Mzz -8.86e+21 ############## ########---------##### ######-------------------### ####-------------------------- ####---------------------------##- ###----------------------------##### ###----------------------------####### ###--------- ---------------########## ##---------- P --------------########### ##----------- -------------############# ##-------------------------############### #------------------------################# #-----------------------################## ---------------------################### #------------------##################### ---------------####################### ------------############## ####### --------################# T ###### ---#################### #### ############################ ###################### ############## Global CMT Convention Moment Tensor: R T P -8.86e+21 -1.06e+22 -1.11e+22 -1.06e+22 5.93e+21 4.43e+21 -1.11e+22 4.43e+21 2.93e+21 Details of the solution is found at http://www.eas.slu.edu/eqc/eqc_mt/MECH.NA/20130914102534/index.html |
Initial Hydra Processing Preliminary |
(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.
|
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 a -30 a 210 rtr taper w 0.1 hp c 0.02 n 3 lp c 0.04 n 3 br c 0.12 0.25 n 4 p 2The results of this grid search from 0.5 to 19 km depth are as follow:
DEPTH STK DIP RAKE MW FIT WVFGRD96 0.5 70 55 -60 3.82 0.5109 WVFGRD96 1.0 75 65 -35 3.88 0.5138 WVFGRD96 2.0 255 55 -30 3.92 0.5255 WVFGRD96 3.0 255 60 -30 3.97 0.5162 WVFGRD96 4.0 70 85 -70 4.16 0.4943 WVFGRD96 5.0 225 10 -100 4.13 0.5306 WVFGRD96 6.0 60 80 -85 4.10 0.5513 WVFGRD96 7.0 50 75 -95 4.07 0.5611 WVFGRD96 8.0 60 80 -85 4.13 0.5701 WVFGRD96 9.0 45 75 -95 4.10 0.5752 WVFGRD96 10.0 250 15 -70 4.08 0.5742 WVFGRD96 11.0 255 20 -55 4.07 0.5684 WVFGRD96 12.0 255 20 -55 4.05 0.5608 WVFGRD96 13.0 260 20 -50 4.04 0.5507 WVFGRD96 14.0 265 20 -45 4.02 0.5396 WVFGRD96 15.0 270 20 -35 4.01 0.5278 WVFGRD96 16.0 280 25 -20 4.01 0.5162 WVFGRD96 17.0 285 25 -10 4.01 0.5053 WVFGRD96 18.0 290 25 -5 4.01 0.4943 WVFGRD96 19.0 290 25 5 4.02 0.4837 WVFGRD96 20.0 295 25 10 4.01 0.4736 WVFGRD96 21.0 300 25 10 4.01 0.4631 WVFGRD96 22.0 300 25 15 4.02 0.4529 WVFGRD96 23.0 305 25 20 4.02 0.4432 WVFGRD96 24.0 310 25 25 4.02 0.4335 WVFGRD96 25.0 315 25 30 4.02 0.4240 WVFGRD96 26.0 315 25 35 4.03 0.4147 WVFGRD96 27.0 315 30 35 4.04 0.4060 WVFGRD96 28.0 320 30 40 4.04 0.3978 WVFGRD96 29.0 325 30 45 4.05 0.3901
The best solution is
WVFGRD96 9.0 45 75 -95 4.10 0.5752
The mechanism correspond to the best fit is
|
The best fit as a function of depth is given in the following figure:
|
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 a -30 a 210 rtr taper w 0.1 hp c 0.02 n 3 lp c 0.04 n 3 br c 0.12 0.25 n 4 p 2
|
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: