2014/02/03 09:03:21 37.128 97.772 5.0 3.9 Kansas
USGS Felt map for this earthquake
USGS/SLU Moment Tensor Solution ENS 2014/02/03 09:03:21:0 37.13 97.77 5.0 3.9 Kansas Best Fitting Double Couple Mo = 2.85e+21 dynecm Mw = 3.57 Z = 3 km Plane Strike Dip Rake NP1 195 50 120 NP2 57 48 59 Principal Axes: Axis Value Plunge Azimuth T 2.85e+21 1 306 N 0.00e+00 23 215 P 2.85e+21 67 38 Moment Tensor: (dynecm) Component Value Mxx 7.09e+20 Mxy 1.55e+21 Mxz 7.74e+20 Myy 1.72e+21 Myz 6.51e+20 Mzz 2.43e+21 ########### ########### ############ ########### T ########## ######### ############# ############ ### ########### P #### ########### ##### ################# ################## ################### ################## #################### ##################### ####################### ######################## ######################## ###################### ################## ############# Global CMT Convention Moment Tensor: R T P 2.43e+21 7.74e+20 6.51e+20 7.74e+20 7.09e+20 1.55e+21 6.51e+20 1.55e+21 1.72e+21 Details of the solution is found at http://www.eas.slu.edu/eqc/eqc_mt/MECH.NA/20140203090321/index.html 
STK = 195 DIP = 50 RAKE = 120 MW = 3.57 HS = 3.0
The NDK file is 20140203090321.ndk The waveform inversion is preferred.
The following compares this source inversion to others
USGS/SLU Moment Tensor Solution ENS 2014/02/03 09:03:21:0 37.13 97.77 5.0 3.9 Kansas Best Fitting Double Couple Mo = 2.85e+21 dynecm Mw = 3.57 Z = 3 km Plane Strike Dip Rake NP1 195 50 120 NP2 57 48 59 Principal Axes: Axis Value Plunge Azimuth T 2.85e+21 1 306 N 0.00e+00 23 215 P 2.85e+21 67 38 Moment Tensor: (dynecm) Component Value Mxx 7.09e+20 Mxy 1.55e+21 Mxz 7.74e+20 Myy 1.72e+21 Myz 6.51e+20 Mzz 2.43e+21 ########### ########### ############ ########### T ########## ######### ############# ############ ### ########### P #### ########### ##### ################# ################## ################### ################## #################### ##################### ####################### ######################## ######################## ###################### ################## ############# Global CMT Convention Moment Tensor: R T P 2.43e+21 7.74e+20 6.51e+20 7.74e+20 7.09e+20 1.55e+21 6.51e+20 1.55e+21 1.72e+21 Details of the solution is found at http://www.eas.slu.edu/eqc/eqc_mt/MECH.NA/20140203090321/index.html 

(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 following figure shows the stations used in the grid search for the best focal mechanism to fit the surfacewave spectral amplitudes of the Love and Rayleigh waves.

The surfacewave determined focal mechanism is shown here.
NODAL PLANES STK= 194.99 DIP= 50.00 RAKE= 120.00 OR STK= 56.91 DIP= 48.44 RAKE= 59.22 DEPTH = 3.0 km Mw = 3.57 Best Fit 0.8189  PT axis plot gives solutions with FIT greater than FIT90
The Pwave first motion data for focal mechanism studies are as follow:
Sta Az Dist First motion
Surface wave analysis was performed using codes from Computer Programs in Seismology, specifically the multiple filter analysis program do_mft and the surfacewave radiation pattern search program srfgrd96.
Digital data were collected, instrument response removed and traces converted
to Z, R an T components. Multiple filter analysis was applied to the Z and T traces to obtain the Rayleigh and Lovewave spectral amplitudes, respectively.
These were input to the search program which examined all depths between 1 and 25 km
and all possible mechanisms.

Pressuretension axis trends. Since the surfacewave spectra search does not distinguish between P and T axes and since there is a 180 ambiguity in strike, all possible P and T axes are plotted. First motion data and waveforms will be used to select the preferred mechanism. The purpose of this plot is to provide an idea of the possible range of solutions. The P and Taxes for all mechanisms with goodness of fit greater than 0.9 FITMAX (above) are plotted here. 
Focal mechanism sensitivity at the preferred depth. The red color indicates a very good fit to the Love and Rayleigh wave radiation patterns. 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. Because of the symmetry of the spectral amplitude rediation patterns, only strikes from 0180 degrees are sampled. 
The distribution of broadband stations with azimuth and distance is
Listing of broadband stations used
Since the analysis of the surfacewave radiation patterns uses only spectral amplitudes and because the surfavewave radiation patterns have a 180 degree symmetry, each surfacewave solution consists of four possible focal mechanisms corresponding to the interchange of the P and Taxes and a roation of the mechanism by 180 degrees. To select one mechanism, Pwave first motion can be used. This was not possible in this case because all the Pwave first motions were emergent ( a feature of the Pwave wave takeoff angle, the station location and the mechanism). The other way to select among the mechanisms is to compute forward synthetics and compare the observed and predicted waveforms.
The fits to the waveforms with the given mechanism are show below:
This figure shows the fit to the three components of motion (Z  vertical, Rradial and T  transverse). For each station and component, the observed traces is shown in red and the model predicted trace in blue. The traces represent filtered ground velocity in units of meters/sec (the peak value is printed adjacent to each trace; each pair of traces to plotted to the same scale to emphasize the difference in levels). Both synthetic and observed traces have been filtered using the SAC commands:
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 1D 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 0.302E02 0.679E02 0.00 0.00 1.00 1.00 6.1000 5.5445 3.2953 2.6089 0.349E02 0.784E02 0.00 0.00 1.00 1.00 13.0000 6.2708 3.7396 2.7812 0.212E02 0.476E02 0.00 0.00 1.00 1.00 19.0000 6.4075 3.7680 2.8223 0.111E02 0.249E02 0.00 0.00 1.00 1.00 0.0000 7.9000 4.6200 3.2760 0.164E10 0.370E10 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: