The ANSS event ID is nm603867 and the event page is at https://earthquake.usgs.gov/earthquakes/eventpage/nm603867/executive.
1991/05/04 01:18:54 36.575 -89.825 11.2 4.13 Missouri
USGS/SLU Moment Tensor Solution ENS 1991/05/04 01:18:54:0 36.575 -89.825 11.2 4.1 Missouri Stations used: Filtering commands used: Best Fitting Double Couple Mo = 1.97e+22 dyne-cm Mw = 4.13 Z = 8 km Plane Strike Dip Rake NP1 352 72 156 NP2 90 67 20 Principal Axes: Axis Value Plunge Azimuth T 1.97e+22 30 310 N 0.00e+00 60 137 P -1.97e+22 3 42 Moment Tensor: (dyne-cm) Component Value Mxx -4.85e+21 Mxy -1.71e+22 Mxz 4.69e+21 Myy -1.49e+15 Myz -7.24e+21 Mzz 4.85e+21 #####--------- ##########------------ ##############----------- P ################---------- - ##### ###########--------------- ###### T ###########---------------- ####### ############---------------- ########################---------------- ########################---------------- #########################----------------- ##########################---------------- -#########################---------------# -----#####################-----------##### ---------################------######### -------------------------############### ------------------------############## -----------------------############# ----------------------############ --------------------########## ------------------########## ---------------####### ----------#### Global CMT Convention Moment Tensor: R T P 4.85e+21 4.69e+21 7.24e+21 4.69e+21 -4.85e+21 1.71e+22 7.24e+21 1.71e+22 -1.49e+15 Details of the solution is found at http://www.eas.slu.edu/eqc/eqc_mt/MECH.NA/19910504011854/index.html |
STK = 90 DIP = 67 RAKE = 20 MW = 4.13 HS = 8
The NDK file is 19910504011854.ndk
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Older earthquake were studied using analog seismograms, which were digitized and analyzed. The original data are not longer available. However focal mechanism solutions based on the waveforms are given in published literature. At the same time, a given earthquake may have been analyzed independently, and the reference is given here.
For this earthquake the source reference is the following:
Herrmann, R. B., and C. J. Ammon (1997). Faulting parameters of earthquakes in the New Madrid, Missouri region, Engineering Geology 46, 299-311.
The CUS 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 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