2013/07/30 12:58:33 45.14 15.08 20.0 4.6 Croatia
USGS Felt map for this earthquake
USGS/SLU Moment Tensor Solution
ENS 2013/07/30 12:58:33:0 45.14 15.08 20.0 4.6 Croatia
Stations used:
BA.PZUN CH.VDL CZ.JAVC CZ.KHC CZ.KRUC CZ.TREC CZ.VRAC
GE.MORC GE.PSZ GR.FUR GR.GEC2 GR.GRB5 GR.UBR GR.WET HU.BEHE
HU.BUD HU.SOP IV.AOI IV.ASQU IV.BDI IV.BOB IV.BRMO IV.BSSO
IV.CAFI IV.CESI IV.CING IV.CRMI IV.FAGN IV.FDMO IV.FIAM
IV.FRES IV.FVI IV.MABI IV.MELA IV.MURB IV.NRCA IV.PARC
IV.PESA IV.PTQR IV.ROVR IV.SACS IV.SGRT IV.SNTG IV.T0104
IV.TEOL IV.TERO MN.BLY MN.TUE MN.VLC OE.ABTA OE.ARSA
OE.CONA OE.CSNA OE.DAVA OE.FETA OE.MOA OE.MYKA OE.OBKA
OE.RETA OE.SOKA OE.WTTA SJ.BBLS SJ.FRGS SL.CADS SL.CEY
SL.CRES SL.CRNS SL.GBAS SL.GBRS SL.GCIS SL.GORS SL.JAVS
SL.KNDS SL.KOGS SL.LJU SL.MOZS SL.PERS SL.ROBS SL.SKDS
SL.VISS SL.VNDS SL.VOJS
Filtering commands used:
cut a -20 a 180
rtr
taper w 0.1
hp c 0.02 n 3
lp c 0.06 n 3
Best Fitting Double Couple
Mo = 3.09e+22 dyne-cm
Mw = 4.26
Z = 17 km
Plane Strike Dip Rake
NP1 215 75 30
NP2 116 61 163
Principal Axes:
Axis Value Plunge Azimuth
T 3.09e+22 32 79
N 0.00e+00 57 239
P -3.09e+22 9 343
Moment Tensor: (dyne-cm)
Component Value
Mxx -2.68e+22
Mxy 1.25e+22
Mxz -2.00e+21
Myy 1.91e+22
Myz 1.49e+22
Mzz 7.73e+21
-----------
---- P ---------------
------- --------------####
----------------------########
----------------------############
---------------------###############
#--------------------#################
##------------------####################
####---------------############## ####
######------------################ T #####
#######----------################# #####
#########-------##########################
############---###########################
########################################
############-----#######################
##########----------##################
########------------------#######---
######----------------------------
####--------------------------
##--------------------------
----------------------
--------------
Global CMT Convention Moment Tensor:
R T P
7.73e+21 -2.00e+21 -1.49e+22
-2.00e+21 -2.68e+22 -1.25e+22
-1.49e+22 -1.25e+22 1.91e+22
Details of the solution is found at
http://www.eas.slu.edu/eqc/eqc_mt/MECH.EU/20130730125833/index.html
|
STK = 215
DIP = 75
RAKE = 30
MW = 4.26
HS = 17.0
The NDK file is 20130730125833.ndk The waveform inversion is preferred.
The following compares this source inversion to others
USGS/SLU Moment Tensor Solution
ENS 2013/07/30 12:58:33:0 45.14 15.08 20.0 4.6 Croatia
Stations used:
BA.PZUN CH.VDL CZ.JAVC CZ.KHC CZ.KRUC CZ.TREC CZ.VRAC
GE.MORC GE.PSZ GR.FUR GR.GEC2 GR.GRB5 GR.UBR GR.WET HU.BEHE
HU.BUD HU.SOP IV.AOI IV.ASQU IV.BDI IV.BOB IV.BRMO IV.BSSO
IV.CAFI IV.CESI IV.CING IV.CRMI IV.FAGN IV.FDMO IV.FIAM
IV.FRES IV.FVI IV.MABI IV.MELA IV.MURB IV.NRCA IV.PARC
IV.PESA IV.PTQR IV.ROVR IV.SACS IV.SGRT IV.SNTG IV.T0104
IV.TEOL IV.TERO MN.BLY MN.TUE MN.VLC OE.ABTA OE.ARSA
OE.CONA OE.CSNA OE.DAVA OE.FETA OE.MOA OE.MYKA OE.OBKA
OE.RETA OE.SOKA OE.WTTA SJ.BBLS SJ.FRGS SL.CADS SL.CEY
SL.CRES SL.CRNS SL.GBAS SL.GBRS SL.GCIS SL.GORS SL.JAVS
SL.KNDS SL.KOGS SL.LJU SL.MOZS SL.PERS SL.ROBS SL.SKDS
SL.VISS SL.VNDS SL.VOJS
Filtering commands used:
cut a -20 a 180
rtr
taper w 0.1
hp c 0.02 n 3
lp c 0.06 n 3
Best Fitting Double Couple
Mo = 3.09e+22 dyne-cm
Mw = 4.26
Z = 17 km
Plane Strike Dip Rake
NP1 215 75 30
NP2 116 61 163
Principal Axes:
Axis Value Plunge Azimuth
T 3.09e+22 32 79
N 0.00e+00 57 239
P -3.09e+22 9 343
Moment Tensor: (dyne-cm)
Component Value
Mxx -2.68e+22
Mxy 1.25e+22
Mxz -2.00e+21
Myy 1.91e+22
Myz 1.49e+22
Mzz 7.73e+21
-----------
---- P ---------------
------- --------------####
----------------------########
----------------------############
---------------------###############
#--------------------#################
##------------------####################
####---------------############## ####
######------------################ T #####
#######----------################# #####
#########-------##########################
############---###########################
########################################
############-----#######################
##########----------##################
########------------------#######---
######----------------------------
####--------------------------
##--------------------------
----------------------
--------------
Global CMT Convention Moment Tensor:
R T P
7.73e+21 -2.00e+21 -1.49e+22
-2.00e+21 -2.68e+22 -1.25e+22
-1.49e+22 -1.25e+22 1.91e+22
Details of the solution is found at
http://www.eas.slu.edu/eqc/eqc_mt/MECH.EU/20130730125833/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:
cut a -20 a 180 rtr taper w 0.1 hp c 0.02 n 3 lp c 0.06 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 -5 45 -90 3.91 0.3093
WVFGRD96 1.0 25 85 5 3.81 0.3077
WVFGRD96 2.0 30 70 20 3.92 0.3939
WVFGRD96 3.0 30 70 20 3.98 0.4262
WVFGRD96 4.0 200 65 -50 4.08 0.4478
WVFGRD96 5.0 200 65 -50 4.10 0.4875
WVFGRD96 6.0 20 70 -35 4.09 0.5192
WVFGRD96 7.0 25 75 -35 4.10 0.5513
WVFGRD96 8.0 20 70 -40 4.16 0.5802
WVFGRD96 9.0 25 75 -40 4.16 0.6053
WVFGRD96 10.0 25 75 -35 4.18 0.6283
WVFGRD96 11.0 220 70 40 4.20 0.6518
WVFGRD96 12.0 220 70 40 4.21 0.6800
WVFGRD96 13.0 215 75 35 4.22 0.7011
WVFGRD96 14.0 215 75 35 4.23 0.7160
WVFGRD96 15.0 215 75 35 4.24 0.7256
WVFGRD96 16.0 215 75 35 4.25 0.7310
WVFGRD96 17.0 215 75 30 4.26 0.7337
WVFGRD96 18.0 215 75 30 4.26 0.7334
WVFGRD96 19.0 215 75 30 4.27 0.7302
WVFGRD96 20.0 215 75 30 4.28 0.7250
WVFGRD96 21.0 210 80 30 4.29 0.7194
WVFGRD96 22.0 210 80 30 4.30 0.7122
WVFGRD96 23.0 210 80 30 4.30 0.7038
WVFGRD96 24.0 210 80 30 4.31 0.6944
WVFGRD96 25.0 210 80 25 4.32 0.6843
WVFGRD96 26.0 210 80 25 4.32 0.6736
WVFGRD96 27.0 210 80 25 4.33 0.6621
WVFGRD96 28.0 210 80 25 4.33 0.6500
WVFGRD96 29.0 210 80 25 4.34 0.6372
The best solution is
WVFGRD96 17.0 215 75 30 4.26 0.7337
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 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 180 rtr taper w 0.1 hp c 0.02 n 3 lp c 0.06 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. |
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 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
Here we tabulate the reasons for not using certain digital data sets
The following stations did not have a valid response files:
DATE=Tue Jul 30 10:18:31 CDT 2013