Location
Location ANSS
2020/03/22 05:24:03 45.87 16.02 10.0 5.4 Croatia
Focal Mechanism
USGS/SLU Moment Tensor Solution
ENS 2020/03/22 05:24:03:0 45.87 16.02 10.0 5.4 Croatia
Stations used:
AC.KBN BW.BE1 BW.KW1 BW.MGS04 BW.RTBE BW.WETR GR.FUR
GR.GEC2 GR.GRA2 GR.GRC3 GR.UBR GR.WET HU.BEHE HU.BUD
HU.CSKK HU.MORH HU.MPLH HU.PSZ HU.SOP IU.GRFO MN.BLY MN.PDG
OE.ARSA OE.BIOA OE.CONA OE.CSNA OE.DAVA OE.KBA OE.MOA
OE.MYKA OE.OBKA OE.RONA OE.SOKA OE.VIE OX.ACOM OX.CGRP
OX.DRE OX.FUSE OX.PRED OX.SABO PL.NIE RO.MDVR SX.GUNZ
SX.WERD
Filtering commands used:
cut o DIST/3.3 -30 o DIST/3.3 +70
rtr
taper w 0.1
hp c 0.02 n 3
lp c 0.06 n 3
Best Fitting Double Couple
Mo = 6.68e+23 dyne-cm
Mw = 5.15
Z = 8 km
Plane Strike Dip Rake
NP1 55 50 60
NP2 277 48 121
Principal Axes:
Axis Value Plunge Azimuth
T 6.68e+23 67 258
N 0.00e+00 23 75
P -6.68e+23 1 166
Moment Tensor: (dyne-cm)
Component Value
Mxx -6.23e+23
Mxy 1.80e+23
Mxz -4.09e+22
Myy 5.30e+22
Myz -2.34e+23
Mzz 5.70e+23
--------------
----------------------
----------------------------
------------------------------
----------------------------------
-----------#########---------------#
------######################--------##
----#############################----###
-##################################-####
-###################################--####
############## ##################-----##
############## T #################-------#
############## ################---------
##############################----------
############################------------
#########################-------------
#####################---------------
###############-------------------
------------------------------
----------------------------
--------------- ----
----------- P
Global CMT Convention Moment Tensor:
R T P
5.70e+23 -4.09e+22 2.34e+23
-4.09e+22 -6.23e+23 -1.80e+23
2.34e+23 -1.80e+23 5.30e+22
Details of the solution is found at
http://www.eas.slu.edu/eqc/eqc_mt/MECH.NA/20200322052403/index.html
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Preferred Solution
The preferred solution from an analysis of the surface-wave spectral amplitude radiation pattern, waveform inversion and first motion observations is
STK = 55
DIP = 50
RAKE = 60
MW = 5.15
HS = 8.0
The NDK file is 20200322052403.ndk
The waveform inversion is preferred.
Moment Tensor Comparison
The following compares this source inversion to others
| SLU |
USGSW |
OTHER |
USGS/SLU Moment Tensor Solution
ENS 2020/03/22 05:24:03:0 45.87 16.02 10.0 5.4 Croatia
Stations used:
AC.KBN BW.BE1 BW.KW1 BW.MGS04 BW.RTBE BW.WETR GR.FUR
GR.GEC2 GR.GRA2 GR.GRC3 GR.UBR GR.WET HU.BEHE HU.BUD
HU.CSKK HU.MORH HU.MPLH HU.PSZ HU.SOP IU.GRFO MN.BLY MN.PDG
OE.ARSA OE.BIOA OE.CONA OE.CSNA OE.DAVA OE.KBA OE.MOA
OE.MYKA OE.OBKA OE.RONA OE.SOKA OE.VIE OX.ACOM OX.CGRP
OX.DRE OX.FUSE OX.PRED OX.SABO PL.NIE RO.MDVR SX.GUNZ
SX.WERD
Filtering commands used:
cut o DIST/3.3 -30 o DIST/3.3 +70
rtr
taper w 0.1
hp c 0.02 n 3
lp c 0.06 n 3
Best Fitting Double Couple
Mo = 6.68e+23 dyne-cm
Mw = 5.15
Z = 8 km
Plane Strike Dip Rake
NP1 55 50 60
NP2 277 48 121
Principal Axes:
Axis Value Plunge Azimuth
T 6.68e+23 67 258
N 0.00e+00 23 75
P -6.68e+23 1 166
Moment Tensor: (dyne-cm)
Component Value
Mxx -6.23e+23
Mxy 1.80e+23
Mxz -4.09e+22
Myy 5.30e+22
Myz -2.34e+23
Mzz 5.70e+23
--------------
----------------------
----------------------------
------------------------------
----------------------------------
-----------#########---------------#
------######################--------##
----#############################----###
-##################################-####
-###################################--####
############## ##################-----##
############## T #################-------#
############## ################---------
##############################----------
############################------------
#########################-------------
#####################---------------
###############-------------------
------------------------------
----------------------------
--------------- ----
----------- P
Global CMT Convention Moment Tensor:
R T P
5.70e+23 -4.09e+22 2.34e+23
-4.09e+22 -6.23e+23 -1.80e+23
2.34e+23 -1.80e+23 5.30e+22
Details of the solution is found at
http://www.eas.slu.edu/eqc/eqc_mt/MECH.NA/20200322052403/index.html
|
W-phase Moment Tensor (Mww)
Moment 1.205e+17 N-m
Magnitude 5.32 Mww
Depth 11.5 km
Percent DC 98%
Half Duration 1.18 s
Catalog US
Data Source US 1
Contributor US 1
Nodal Planes
Plane Strike Dip Rake
NP1 263 39 97
NP2 74 51 84
Principal Axes
Axis Value Plunge Azimuth
T 1.199e+17 N-m 82 310
N 0.011e+17 N-m 5 78
P -1.211e+17 N-m 6 168
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EMSC-CSEM Summary
|
Magnitudes
ML Magnitude
(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.
Context
The next figure presents the focal mechanism for this earthquake (red) in the context of other events (blue) in the SLU Moment Tensor Catalog which are within ± 0.5 degrees of the new event. This comparison is shown in the left panel of the figure. The right panel shows the inferred direction of maximum compressive stress and the type of faulting (green is strike-slip, red is normal, blue is thrust; oblique is shown by a combination of colors).
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.
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Location of broadband stations used for waveform inversion
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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 o DIST/3.3 -30 o DIST/3.3 +70
rtr
taper w 0.1
hp c 0.02 n 3
lp c 0.06 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 1.0 210 90 10 4.76 0.3023
WVFGRD96 2.0 30 90 -20 4.87 0.3769
WVFGRD96 3.0 45 60 50 4.99 0.4261
WVFGRD96 4.0 50 55 55 5.04 0.4804
WVFGRD96 5.0 50 55 55 5.06 0.5174
WVFGRD96 6.0 55 50 60 5.09 0.5371
WVFGRD96 7.0 45 55 45 5.08 0.5413
WVFGRD96 8.0 55 50 60 5.15 0.5770
WVFGRD96 9.0 45 55 45 5.13 0.5585
WVFGRD96 10.0 40 60 35 5.11 0.5412
WVFGRD96 11.0 215 70 25 5.11 0.5338
WVFGRD96 12.0 215 70 20 5.11 0.5246
WVFGRD96 13.0 215 75 20 5.12 0.5157
WVFGRD96 14.0 30 90 -20 5.12 0.5073
WVFGRD96 15.0 215 75 20 5.13 0.5006
WVFGRD96 16.0 215 75 20 5.14 0.4943
WVFGRD96 17.0 210 80 -15 5.15 0.4902
WVFGRD96 18.0 210 80 -15 5.15 0.4856
WVFGRD96 19.0 210 80 -15 5.16 0.4797
WVFGRD96 20.0 210 80 -15 5.17 0.4734
WVFGRD96 21.0 210 80 -15 5.18 0.4673
WVFGRD96 22.0 210 80 -15 5.19 0.4610
WVFGRD96 23.0 210 80 -15 5.19 0.4542
WVFGRD96 24.0 210 80 -15 5.20 0.4469
WVFGRD96 25.0 210 80 -15 5.21 0.4389
WVFGRD96 26.0 210 80 -15 5.21 0.4309
WVFGRD96 27.0 210 80 -15 5.22 0.4223
WVFGRD96 28.0 210 80 -15 5.23 0.4134
WVFGRD96 29.0 210 80 -15 5.23 0.4043
The best solution is
WVFGRD96 8.0 55 50 60 5.15 0.5770
The mechanism correspond to the best fit is
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Figure 1. Waveform inversion focal mechanism
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The best fit as a function of depth is given in the following figure:
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Figure 2. Depth sensitivity for waveform mechanism
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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 o DIST/3.3 -30 o DIST/3.3 +70
rtr
taper w 0.1
hp c 0.02 n 3
lp c 0.06 n 3
|
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Figure 3. Waveform comparison for selected depth
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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.
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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
Acknowledgements
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.
Velocity Model
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
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:
Last Changed Sun Mar 22 10:29:58 CDT 2020
