2013/11/18 07:58:41 43.66 16.86 2.0 4.8 Croatia
USGS Felt map for this earthquake
USGS/SLU Moment Tensor Solution
ENS 2013/11/18 07:58:41:0 43.66 16.86 2.0 4.8 Croatia
Stations used:
BS.PLD CH.BERNI GR.FUR GR.GEC2 GR.UBR GR.WET HT.FNA HT.GRG
MN.BLY MN.PDG MN.VTS OE.ABTA OE.ARSA OE.CONA OE.CSNA
OE.FETA OE.KBA OE.MOA OE.MYKA OE.OBKA OE.RETA OE.SOKA
OE.WTTA SL.BOJS SL.CADS SL.CEY SL.CRES SL.CRNS SL.DOBS
SL.GBAS SL.GBRS SL.GCIS SL.GORS SL.GROS 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 0.05 n 3
Best Fitting Double Couple
Mo = 2.43e+22 dyne-cm
Mw = 4.19
Z = 12 km
Plane Strike Dip Rake
NP1 127 61 132
NP2 245 50 40
Principal Axes:
Axis Value Plunge Azimuth
T 2.43e+22 53 90
N 0.00e+00 36 282
P -2.43e+22 6 188
Moment Tensor: (dyne-cm)
Component Value
Mxx -2.35e+22
Mxy -3.27e+21
Mxz 2.59e+21
Myy 8.16e+21
Myz 1.20e+22
Mzz 1.54e+22
--------------
----------------------
----------------------------
------------------------------
----------------------------------
##--------------##################--
###----------#########################
#####------#############################
######---###############################
############################# ##########
######---#################### T ##########
#####------################## ##########
####---------#############################
##------------##########################
##--------------########################
------------------####################
---------------------###############
-------------------------#########
------------------------------
----------------------------
------- ------------
--- P --------
Global CMT Convention Moment Tensor:
R T P
1.54e+22 2.59e+21 -1.20e+22
2.59e+21 -2.35e+22 3.27e+21
-1.20e+22 3.27e+21 8.16e+21
Details of the solution is found at
http://www.eas.slu.edu/eqc/eqc_mt/MECH.EU/20131118075841/index.html
|
STK = 245
DIP = 50
RAKE = 40
MW = 4.19
HS = 12.0
The NDK file is 20131118075841.ndk The waveform inversion is preferred.
The following compares this source inversion to others
USGS/SLU Moment Tensor Solution
ENS 2013/11/18 07:58:41:0 43.66 16.86 2.0 4.8 Croatia
Stations used:
BS.PLD CH.BERNI GR.FUR GR.GEC2 GR.UBR GR.WET HT.FNA HT.GRG
MN.BLY MN.PDG MN.VTS OE.ABTA OE.ARSA OE.CONA OE.CSNA
OE.FETA OE.KBA OE.MOA OE.MYKA OE.OBKA OE.RETA OE.SOKA
OE.WTTA SL.BOJS SL.CADS SL.CEY SL.CRES SL.CRNS SL.DOBS
SL.GBAS SL.GBRS SL.GCIS SL.GORS SL.GROS 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 0.05 n 3
Best Fitting Double Couple
Mo = 2.43e+22 dyne-cm
Mw = 4.19
Z = 12 km
Plane Strike Dip Rake
NP1 127 61 132
NP2 245 50 40
Principal Axes:
Axis Value Plunge Azimuth
T 2.43e+22 53 90
N 0.00e+00 36 282
P -2.43e+22 6 188
Moment Tensor: (dyne-cm)
Component Value
Mxx -2.35e+22
Mxy -3.27e+21
Mxz 2.59e+21
Myy 8.16e+21
Myz 1.20e+22
Mzz 1.54e+22
--------------
----------------------
----------------------------
------------------------------
----------------------------------
##--------------##################--
###----------#########################
#####------#############################
######---###############################
############################# ##########
######---#################### T ##########
#####------################## ##########
####---------#############################
##------------##########################
##--------------########################
------------------####################
---------------------###############
-------------------------#########
------------------------------
----------------------------
------- ------------
--- P --------
Global CMT Convention Moment Tensor:
R T P
1.54e+22 2.59e+21 -1.20e+22
2.59e+21 -2.35e+22 3.27e+21
-1.20e+22 3.27e+21 8.16e+21
Details of the solution is found at
http://www.eas.slu.edu/eqc/eqc_mt/MECH.EU/20131118075841/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 0.05 n 3The results of this grid search from 0.5 to 19 km depth are as follow:
DEPTH STK DIP RAKE MW FIT
WVFGRD96 0.5 230 65 -25 3.88 0.2983
WVFGRD96 1.0 235 70 -25 3.88 0.3096
WVFGRD96 2.0 230 70 -35 3.97 0.3524
WVFGRD96 3.0 230 80 -50 4.05 0.3737
WVFGRD96 4.0 230 80 -45 4.04 0.4022
WVFGRD96 5.0 235 85 -40 4.04 0.4278
WVFGRD96 6.0 235 85 -35 4.04 0.4505
WVFGRD96 7.0 235 85 -30 4.05 0.4696
WVFGRD96 8.0 70 65 45 4.12 0.4918
WVFGRD96 9.0 260 45 50 4.19 0.5266
WVFGRD96 10.0 260 45 55 4.20 0.5497
WVFGRD96 11.0 255 45 50 4.20 0.5598
WVFGRD96 12.0 245 50 40 4.19 0.5617
WVFGRD96 13.0 245 50 40 4.19 0.5588
WVFGRD96 14.0 240 55 35 4.18 0.5556
WVFGRD96 15.0 240 60 30 4.17 0.5509
WVFGRD96 16.0 235 65 25 4.17 0.5447
WVFGRD96 17.0 235 65 25 4.18 0.5387
WVFGRD96 18.0 235 65 25 4.18 0.5310
WVFGRD96 19.0 235 70 20 4.18 0.5237
WVFGRD96 20.0 235 75 20 4.18 0.5160
WVFGRD96 21.0 235 75 20 4.19 0.5088
WVFGRD96 22.0 235 75 20 4.19 0.5003
WVFGRD96 23.0 235 80 20 4.20 0.4914
WVFGRD96 24.0 235 80 20 4.20 0.4824
WVFGRD96 25.0 55 90 -15 4.21 0.4733
WVFGRD96 26.0 50 65 -20 4.23 0.4658
WVFGRD96 27.0 50 65 -20 4.24 0.4591
WVFGRD96 28.0 50 65 -20 4.25 0.4528
WVFGRD96 29.0 55 65 -15 4.26 0.4464
The best solution is
WVFGRD96 12.0 245 50 40 4.19 0.5617
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 0.05 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=Mon Nov 18 12:14:26 CST 2013