2014/03/13 17:31:59 45.77 14.79 2.0 4.4 Slovenia
USGS Felt map for this earthquake
USGS/SLU Moment Tensor Solution
ENS 2014/03/13 17:31:59:0 45.77 14.79 2.0 4.4 Slovenia
Stations used:
HU.SOP IV.FVI IV.PTCC OE.ABTA OE.ARSA OE.CONA OE.CSNA
OE.KBA OE.MOA OE.MYKA OE.OBKA SL.BOJS SL.CADS SL.CEY
SL.CRNS SL.DOBS SL.GBAS SL.GCIS SL.GORS SL.JAVS SL.KNDS
SL.KOGS SL.LJU SL.MOZS SL.PERS
Filtering commands used:
cut a -20 a 110
rtr
taper w 0.1
hp c 0.03 n 3
lp c 0.10 n 3
Best Fitting Double Couple
Mo = 1.66e+22 dyne-cm
Mw = 4.08
Z = 2 km
Plane Strike Dip Rake
NP1 265 50 80
NP2 100 41 102
Principal Axes:
Axis Value Plunge Azimuth
T 1.66e+22 81 122
N 0.00e+00 8 271
P -1.66e+22 5 2
Moment Tensor: (dyne-cm)
Component Value
Mxx -1.64e+22
Mxy -7.77e+20
Mxz -2.67e+21
Myy 2.61e+20
Myz 2.09e+21
Mzz 1.61e+22
------ P -----
---------- ---------
----------------------------
------------------------------
----------------------------------
------------------------------------
----------#####################-------
-------#############################----
-----#################################--
#---#####################################-
#-################### ##################
#-################### T ##################
----################# ##################
----####################################
------################################--
-------############################---
----------#####################-----
---------------#########----------
------------------------------
----------------------------
----------------------
--------------
Global CMT Convention Moment Tensor:
R T P
1.61e+22 -2.67e+21 -2.09e+21
-2.67e+21 -1.64e+22 7.77e+20
-2.09e+21 7.77e+20 2.61e+20
Details of the solution is found at
http://www.eas.slu.edu/eqc/eqc_mt/MECH.EU/20140313173159/index.html
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STK = 265
DIP = 50
RAKE = 80
MW = 4.08
HS = 2.0
The NDK file is 20140313173159.ndk Traces were noisy because of earlier event in Japan. The initial search wanted a shallow depth, but the WUS Green's functions had significant hsort period surface waves not seen in the data. So I decided to use the CUS model.
The following compares this source inversion to others
USGS/SLU Moment Tensor Solution
ENS 2014/03/13 17:31:59:0 45.77 14.79 2.0 4.4 Slovenia
Stations used:
HU.SOP IV.FVI IV.PTCC OE.ABTA OE.ARSA OE.CONA OE.CSNA
OE.KBA OE.MOA OE.MYKA OE.OBKA SL.BOJS SL.CADS SL.CEY
SL.CRNS SL.DOBS SL.GBAS SL.GCIS SL.GORS SL.JAVS SL.KNDS
SL.KOGS SL.LJU SL.MOZS SL.PERS
Filtering commands used:
cut a -20 a 110
rtr
taper w 0.1
hp c 0.03 n 3
lp c 0.10 n 3
Best Fitting Double Couple
Mo = 1.66e+22 dyne-cm
Mw = 4.08
Z = 2 km
Plane Strike Dip Rake
NP1 265 50 80
NP2 100 41 102
Principal Axes:
Axis Value Plunge Azimuth
T 1.66e+22 81 122
N 0.00e+00 8 271
P -1.66e+22 5 2
Moment Tensor: (dyne-cm)
Component Value
Mxx -1.64e+22
Mxy -7.77e+20
Mxz -2.67e+21
Myy 2.61e+20
Myz 2.09e+21
Mzz 1.61e+22
------ P -----
---------- ---------
----------------------------
------------------------------
----------------------------------
------------------------------------
----------#####################-------
-------#############################----
-----#################################--
#---#####################################-
#-################### ##################
#-################### T ##################
----################# ##################
----####################################
------################################--
-------############################---
----------#####################-----
---------------#########----------
------------------------------
----------------------------
----------------------
--------------
Global CMT Convention Moment Tensor:
R T P
1.61e+22 -2.67e+21 -2.09e+21
-2.67e+21 -1.64e+22 7.77e+20
-2.09e+21 7.77e+20 2.61e+20
Details of the solution is found at
http://www.eas.slu.edu/eqc/eqc_mt/MECH.EU/20140313173159/index.html
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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.
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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 110 rtr taper w 0.1 hp c 0.03 n 3 lp c 0.10 n 3The results of this grid search from 0.5 to 19 km depth are as follow:
DEPTH STK DIP RAKE MW FIT
WVFGRD96 0.5 245 55 55 3.95 0.3877
WVFGRD96 1.0 255 50 65 4.00 0.4101
WVFGRD96 2.0 265 50 80 4.08 0.4211
WVFGRD96 3.0 270 55 85 4.10 0.3708
WVFGRD96 4.0 40 65 -25 3.99 0.3370
WVFGRD96 5.0 225 70 -30 4.00 0.3444
WVFGRD96 6.0 225 65 -30 4.02 0.3553
WVFGRD96 7.0 225 65 -30 4.03 0.3657
WVFGRD96 8.0 225 65 -30 4.04 0.3745
WVFGRD96 9.0 225 65 -30 4.05 0.3819
WVFGRD96 10.0 220 60 -35 4.08 0.3848
WVFGRD96 11.0 220 60 -35 4.08 0.3888
WVFGRD96 12.0 220 55 -35 4.10 0.3919
WVFGRD96 13.0 220 55 -35 4.11 0.3934
WVFGRD96 14.0 220 55 -35 4.12 0.3928
WVFGRD96 15.0 220 55 -35 4.13 0.3902
WVFGRD96 16.0 220 55 -35 4.13 0.3863
WVFGRD96 17.0 220 55 -35 4.14 0.3815
WVFGRD96 18.0 220 55 -35 4.15 0.3760
WVFGRD96 19.0 220 55 -35 4.15 0.3698
WVFGRD96 20.0 290 55 -65 4.19 0.3667
WVFGRD96 21.0 295 55 -65 4.20 0.3653
WVFGRD96 22.0 290 50 -70 4.21 0.3640
WVFGRD96 23.0 290 50 -70 4.22 0.3616
WVFGRD96 24.0 295 50 -65 4.23 0.3584
WVFGRD96 25.0 295 50 -65 4.23 0.3551
WVFGRD96 26.0 295 50 -65 4.24 0.3514
WVFGRD96 27.0 295 50 -65 4.25 0.3471
WVFGRD96 28.0 295 50 -60 4.25 0.3427
WVFGRD96 29.0 295 50 -60 4.25 0.3369
The best solution is
WVFGRD96 2.0 265 50 80 4.08 0.4211
The mechanism correspond to the best fit is
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The best fit as a function of depth is given in the following figure:
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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 110 rtr taper w 0.1 hp c 0.03 n 3 lp c 0.10 n 3
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| 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.
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.
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 CUS used for the waveform synthetic seismograms and for the surface wave eigenfunctions and dispersion is as follows:
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
Here we tabulate the reasons for not using certain digital data sets
The following stations did not have a valid response files:
DATE=Fri Mar 14 08:16:33 CDT 2014