2010/03/02 19:37:35 36.788 89.357 8.2 3.70 Missouri
USGS Felt map for this earthquake
USGS/SLU Moment Tensor Solution ENS 2010/03/02 19:37:35:0 36.79 89.36 8.2 3.7 Missouri Stations used: NM.HENM NM.HICK NM.PARM Filtering commands used: hp c 0.10 n 3 lp c 0.40 n 3 Best Fitting Double Couple Mo = 1.43e+21 dynecm Mw = 3.37 Z = 5 km Plane Strike Dip Rake NP1 211 86 135 NP2 305 45 5 Principal Axes: Axis Value Plunge Azimuth T 1.43e+21 33 158 N 0.00e+00 45 28 P 1.43e+21 27 267 Moment Tensor: (dynecm) Component Value Mxx 8.62e+20 Mxy 4.03e+20 Mxz 5.77e+20 Myy 9.87e+20 Myz 8.25e+20 Mzz 1.25e+20 ############## ###################### ####################### ################# ######  #### ####### ########## ############  ##############  P #################  ################### ##################### ###################### ####################### ######################## ############ ########## ############# T ######## ############## ####### ###################### ############## Global CMT Convention Moment Tensor: R T P 1.25e+20 5.77e+20 8.25e+20 5.77e+20 8.62e+20 4.03e+20 8.25e+20 4.03e+20 9.87e+20 Details of the solution is found at http://www.eas.slu.edu/eqc/eqc_mt/MECH.NA/20100302193735/index.html 
STK = 305 DIP = 45 RAKE = 5 MW = 3.37 HS = 5.0
This solution is very dependent on the velocity model, filter band and width of the time window. The original PANDA model had 0.65 km of sediments, but this was reduced to 0.35 km because this event was north of the USGS well south of Noranda where the 0.65 km depth was determined. The solution is not unexpected in that the orientation of the Paxis agrees with previous mechanisms and the NNE striking nodal plane lines up with seismicity, e.g., for previous mechanisms and the seismicity .
The following compares this source inversion to others
USGS/SLU Moment Tensor Solution ENS 2010/03/02 19:37:35:0 36.79 89.36 8.2 3.7 Missouri Stations used: NM.HENM NM.HICK NM.PARM Filtering commands used: hp c 0.10 n 3 lp c 0.40 n 3 Best Fitting Double Couple Mo = 1.43e+21 dynecm Mw = 3.37 Z = 5 km Plane Strike Dip Rake NP1 211 86 135 NP2 305 45 5 Principal Axes: Axis Value Plunge Azimuth T 1.43e+21 33 158 N 0.00e+00 45 28 P 1.43e+21 27 267 Moment Tensor: (dynecm) Component Value Mxx 8.62e+20 Mxy 4.03e+20 Mxz 5.77e+20 Myy 9.87e+20 Myz 8.25e+20 Mzz 1.25e+20 ############## ###################### ####################### ################# ######  #### ####### ########## ############  ##############  P #################  ################### ##################### ###################### ####################### ######################## ############ ########## ############# T ######## ############## ####### ###################### ############## Global CMT Convention Moment Tensor: R T P 1.25e+20 5.77e+20 8.25e+20 5.77e+20 8.62e+20 4.03e+20 8.25e+20 4.03e+20 9.87e+20 Details of the solution is found at http://www.eas.slu.edu/eqc/eqc_mt/MECH.NA/20100302193735/index.html 

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:
hp c 0.10 n 3 lp c 0.40 n 3The results of this grid search from 0.5 to 19 km depth are as follow:
DEPTH STK DIP RAKE MW FIT WVFGRD96 1.0 300 55 15 2.94 0.3241 WVFGRD96 2.0 310 40 10 3.06 0.4482 WVFGRD96 3.0 305 50 5 3.15 0.5626 WVFGRD96 4.0 305 60 5 3.22 0.6358 WVFGRD96 5.0 305 45 5 3.37 0.6501 WVFGRD96 6.0 305 50 0 3.41 0.6433 WVFGRD96 7.0 310 50 5 3.45 0.6177 WVFGRD96 8.0 310 55 5 3.46 0.5996 WVFGRD96 9.0 305 70 0 3.43 0.5766 WVFGRD96 10.0 305 70 0 3.46 0.5681 WVFGRD96 11.0 305 75 0 3.46 0.5661 WVFGRD96 12.0 305 80 5 3.47 0.5669 WVFGRD96 13.0 305 80 10 3.51 0.5644 WVFGRD96 14.0 120 90 0 3.48 0.5487 WVFGRD96 15.0 120 85 5 3.46 0.5362 WVFGRD96 16.0 120 85 5 3.48 0.5310
The best solution is
WVFGRD96 5.0 305 45 5 3.37 0.6501
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 observedpredicted componnet is plotted to the same scale and peak amplitudes are indicated by the numbers to the left of each trace. The number in black at the rightr of each predicted traces 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 bandpass filter used in the processing and for the display was
hp c 0.10 n 3 lp c 0.40 n 3

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. 
Should the national backbone of the USGS Advanced National Seismic System (ANSS) be implemented with an interstation separation of 300 km, it is very likely that an earthquake such as this would have been recorded at distances on the order of 100200 km. This means that the closest station would have information on source depth and mechanism that was lacking here.
Dr. Harley Benz, USGS, provided the USGS USNSN digital data. The digital data used in this study were provided by Natural Resources Canada through their AUTODRM site http://www.seismo.nrcan.gc.ca/nwfa/autodrm/autodrm_req_e.php, and IRIS using their BUD interface.
Thanks also to the many seismic network operators whose dedication make this effort possible: University of Alaska, University of Washington, Oregon State University, University of Utah, Montana Bureas of Mines, UC Berkely, Caltech, UC San Diego, Saint L ouis University, Universityof Memphis, Lamont Doehrty Earth Observatory, Boston College, the Iris stations and the Transportable Array of EarthScope.
The PANDA1 model used for the waveform synthetic seismograms and for the surface wave eigenfunctions and dispersion is as follows:
MODEL.01 Panda model for New Madrid ISOTROPIC KGS FLAT EARTH 1D CONSTANT VELOCITY LINE08 LINE09 LINE10 LINE11 H(KM) VP(KM/S) VS(KM/S) RHO(GM/CC) QP QS ETAP ETAS FREFP FREFS 0.3500 1.8000 0.6000 2.0000 200. 100. 0.00 0.00 1.00 1.00 1.8500 6.0200 3.0100 2.0000 200. 100. 0.00 0.00 1.00 1.00 2.5 4.83 2.63 2.0 200. 100. 0.00 0.00 1.00 1.00 12.0 6.17 3.38 2.2 600. 300. 0.00 0.00 1.00 1.00 10.0 6.60 3.68 2.2 600. 300. 0.00 0.00 1.00 1.00 10.0 7.20 3.68 2.2 600. 300. 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:
DATE=Thu Mar 4 10:55:20 CST 2010