Location

2013/12/12 00:59:19 47.06 9.49 3.0 4.1 Liechtenstein

Arrival Times (from USGS)

Felt Map

Focal Mechanism

USGS/SLU Moment Tensor Solution ENS 2013/12/12 00:59:19:0 47.06 9.49 3.0 4.1 Liechtenstein Stations used: CH.BALST CH.BERNI CH.BNALP CH.BOURR CH.BRANT CH.DAVOX CH.FUSIO CH.HASLI CH.LAUCH CH.LIENZ CH.LLS CH.MMK CH.MUO CH.PANIX CH.SENIN CH.SLE CH.SULZ CH.VDL CH.WILA CH.WIMIS CH.ZUR GU.SATI IV.STAL MN.TUE OE.ABTA OE.DAVA OE.FETA OE.KBA OE.MYKA OE.RETA OE.WTTA SL.CADS SL.CRNS SL.GBAS SL.GORS SL.JAVS SL.MOZS SL.ROBS SL.VOJS Filtering commands used: cut a -20 a 140 rtr taper w 0.1 hp c 0.02 n 3 lp c 0.05 n 3 Best Fitting Double Couple Mo = 3.63e+21 dyne-cm Mw = 3.64 Z = 10 km Plane Strike Dip Rake NP1 180 85 25 NP2 88 65 174 Principal Axes: Axis Value Plunge Azimuth T 3.63e+21 21 47 N 0.00e+00 65 191 P -3.63e+21 14 311 Moment Tensor: (dyne-cm) Component Value Mxx -5.73e+14 Mxy 3.28e+21 Mxz 2.87e+20 Myy -2.66e+20 Myz 1.51e+21 Mzz 2.66e+20 -------####### -----------########### -------------############### -----------########### ## -- P -----------########### T #### --- -----------########### ##### ------------------#################### -------------------##################### -------------------##################### --------------------###################### --------------------###################### --------------------####################-- ###-----------------#################----- ######-------------############--------- ###################--------------------- ##################-------------------- #################------------------- ################------------------ ##############---------------- #############--------------- ###########----------- #######------- Global CMT Convention Moment Tensor: R T P 2.66e+20 2.87e+20 -1.51e+21 2.87e+20 -5.73e+14 -3.28e+21 -1.51e+21 -3.28e+21 -2.66e+20 Details of the solution is found at http://www.eas.slu.edu/eqc/eqc_mt/MECH.EU/20131212005919/index.html

Preferred Solution

The preferred solution from an analysis of the surface-wave spectral amplitude radiation pattern, waveform inversion and first motion observations is

      STK = 180
      DIP = 85
     RAKE = 25
       MW = 3.64
       HS = 10.0

The NDK file is 20131212005919.ndk The waveform inversion is preferred.

Moment Tensor Comparison

The following compares this source inversion to others

SLU GFZ

USGS/SLU Moment Tensor Solution ENS 2013/12/12 00:59:19:0 47.06 9.49 3.0 4.1 Liechtenstein Stations used: CH.BALST CH.BERNI CH.BNALP CH.BOURR CH.BRANT CH.DAVOX CH.FUSIO CH.HASLI CH.LAUCH CH.LIENZ CH.LLS CH.MMK CH.MUO CH.PANIX CH.SENIN CH.SLE CH.SULZ CH.VDL CH.WILA CH.WIMIS CH.ZUR GU.SATI IV.STAL MN.TUE OE.ABTA OE.DAVA OE.FETA OE.KBA OE.MYKA OE.RETA OE.WTTA SL.CADS SL.CRNS SL.GBAS SL.GORS SL.JAVS SL.MOZS SL.ROBS SL.VOJS Filtering commands used: cut a -20 a 140 rtr taper w 0.1 hp c 0.02 n 3 lp c 0.05 n 3 Best Fitting Double Couple Mo = 3.63e+21 dyne-cm Mw = 3.64 Z = 10 km Plane Strike Dip Rake NP1 180 85 25 NP2 88 65 174 Principal Axes: Axis Value Plunge Azimuth T 3.63e+21 21 47 N 0.00e+00 65 191 P -3.63e+21 14 311 Moment Tensor: (dyne-cm) Component Value Mxx -5.73e+14 Mxy 3.28e+21 Mxz 2.87e+20 Myy -2.66e+20 Myz 1.51e+21 Mzz 2.66e+20 -------####### -----------########### -------------############### -----------########### ## -- P -----------########### T #### --- -----------########### ##### ------------------#################### -------------------##################### -------------------##################### --------------------###################### --------------------###################### --------------------####################-- ###-----------------#################----- ######-------------############--------- ###################--------------------- ##################-------------------- #################------------------- ################------------------ ##############---------------- #############--------------- ###########----------- #######------- Global CMT Convention Moment Tensor: R T P 2.66e+20 2.87e+20 -1.51e+21 2.87e+20 -5.73e+14 -3.28e+21 -1.51e+21 -3.28e+21 -2.66e+20 Details of the solution is found at http://www.eas.slu.edu/eqc/eqc_mt/MECH.EU/20131212005919/index.html

GFZ Event gfz2013ygkm 13/12/12 00:59:19.26 Germany Epicenter: 47.16 9.54 MW 3.6 GFZ MOMENT TENSOR SOLUTION Depth 5 No. of sta: 49 Moment Tensor; Scale 10**14 Nm Mrr=-0.72 Mtt= 0.33 Mpp= 0.39 Mrt= 0.50 Mrp=-0.46 Mtp=-3.12 Principal axes: T Val= 3.59 Plg= 9 Azm= 45 N -0.83 81 232 P -2.76 1 135 Best Double Couple:Mo=3.3*10**14 NP1:Strike= 90 Dip=84 Slip= 173 NP2: 181 83 6 ------##### --------######### -----------############ ------------############# --------------############### -------------################ --------------################# ---------------################## ---------------################## ---------------################## ###############------------------ ###############------------------ ##############----------------- #############---------------- #############---------------- ############------------- ###########------------ ########--------- #####------

Waveform Inversion

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.

Location of broadband stations used for waveform inversion

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 -20 a 140
rtr
taper w 0.1
hp c 0.02 n 3 
lp c 0.05 n 3

The results of this grid search from 0.5 to 19 km depth are as follow:

           DEPTH  STK   DIP  RAKE   MW    FIT
WVFGRD96    0.5   180    70   -20   3.30 0.3238
WVFGRD96    1.0     5    85    -5   3.31 0.3466
WVFGRD96    2.0     0    80   -20   3.42 0.4426
WVFGRD96    3.0     0    85   -30   3.49 0.4820
WVFGRD96    4.0     0    90   -35   3.53 0.5173
WVFGRD96    5.0     0    90   -30   3.55 0.5472
WVFGRD96    6.0     0    90   -30   3.57 0.5708
WVFGRD96    7.0     0    90   -25   3.58 0.5897
WVFGRD96    8.0     0    90   -30   3.62 0.6036
WVFGRD96    9.0     0    90   -30   3.63 0.6088
WVFGRD96   10.0   180    85    25   3.64 0.6127
WVFGRD96   11.0   180    85    25   3.65 0.6101
WVFGRD96   12.0   180    85    20   3.66 0.6046
WVFGRD96   13.0   180    85    20   3.67 0.5990
WVFGRD96   14.0   180    85    20   3.67 0.5915
WVFGRD96   15.0     0    90   -20   3.68 0.5813
WVFGRD96   16.0     0    90   -20   3.68 0.5732
WVFGRD96   17.0   180    90    20   3.69 0.5638
WVFGRD96   18.0     0    90   -15   3.69 0.5546
WVFGRD96   19.0     0    90   -15   3.70 0.5451
WVFGRD96   20.0   180    90    15   3.70 0.5357
WVFGRD96   21.0   180    90    15   3.71 0.5264
WVFGRD96   22.0     0    90   -15   3.71 0.5176
WVFGRD96   23.0    -5    75   -15   3.72 0.5084
WVFGRD96   24.0     0    60     0   3.75 0.5018
WVFGRD96   25.0     0    60     0   3.75 0.4967
WVFGRD96   26.0     0    60     0   3.76 0.4915
WVFGRD96   27.0     0    60     0   3.76 0.4857
WVFGRD96   28.0     0    60     0   3.77 0.4809
WVFGRD96   29.0     0    60     0   3.77 0.4758

The best solution is

WVFGRD96   10.0   180    85    25   3.64 0.6127

The mechanism correspond to the best fit is

Figure 1. Waveform inversion focal mechanism

The best fit as a function of depth is given in the following figure:

Figure 2. Depth sensitivity for waveform mechanism

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 -20 a 140
rtr
taper w 0.1
hp c 0.02 n 3 
lp c 0.05 n 3

Figure 3. Waveform comparison for selected depth

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:

The origin time and epicentral distance are incorrect
The velocity model used for the inversion is incorrect
The velocity model used to define the P-arrival time is not the same as the velocity model used for the waveform inversion (assuming that the initial trace alignment is based on the P arrival time)

Assuming only a mislocation, the time shifts are fit to a functional form:

 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.

Discussion

The Future

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 100-200 km. This means that the closest station would have information on source depth and mechanism that was lacking here.

Acknowledgements

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.

Velocity Model

The WUS 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

Quality Control

Here we tabulate the reasons for not using certain digital data sets

The following stations did not have a valid response files:

DATE=Thu Dec 12 14:29:53 CST 2013

Last Changed 2013/12/12