2014/01/23 06:15:05 45.42 26.26 127.0 4.7 Romania
USGS Felt map for this earthquake
USGS/SLU Moment Tensor Solution
ENS 2014/01/23 06:15:05:0 45.42 26.26 127.0 4.7 Romania
Stations used:
GE.TIRR RO.ARR RO.CFR RO.ISR RO.MLR RO.PLOR1 RO.TESR
RO.VOIR RO.VRI
Filtering commands used:
cut a -30 a 60
rtr
taper w 0.1
hp c 0.05 n 3
lp c 0.25 n 3
Best Fitting Double Couple
Mo = 4.52e+22 dyne-cm
Mw = 4.37
Z = 118 km
Plane Strike Dip Rake
NP1 277 56 113
NP2 60 40 60
Principal Axes:
Axis Value Plunge Azimuth
T 4.52e+22 69 238
N 0.00e+00 19 84
P -4.52e+22 9 351
Moment Tensor: (dyne-cm)
Component Value
Mxx -4.15e+22
Mxy 9.43e+21
Mxz -1.45e+22
Myy 2.94e+21
Myz -1.16e+22
Mzz 3.85e+22
--- P --------
------- ------------
----------------------------
------------------------------
----------------------------------
------------------------------------
----------###########----------------#
-----########################---------##
--###############################-----##
-####################################-####
######################################-###
############### ###################----#
############### T ##################------
############## ################-------
################################--------
#############################---------
#########################-----------
--###################-------------
-----#######------------------
----------------------------
----------------------
--------------
Global CMT Convention Moment Tensor:
R T P
3.85e+22 -1.45e+22 1.16e+22
-1.45e+22 -4.15e+22 -9.43e+21
1.16e+22 -9.43e+21 2.94e+21
Details of the solution is found at
http://www.eas.slu.edu/eqc/eqc_mt/MECH.EU/20140123061505/index.html
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STK = 60
DIP = 40
RAKE = 60
MW = 4.37
HS = 118.0
The NDK file is 20140123061505.ndk The waveform inversion is preferred.
The following compares this source inversion to others
USGS/SLU Moment Tensor Solution
ENS 2014/01/23 06:15:05:0 45.42 26.26 127.0 4.7 Romania
Stations used:
GE.TIRR RO.ARR RO.CFR RO.ISR RO.MLR RO.PLOR1 RO.TESR
RO.VOIR RO.VRI
Filtering commands used:
cut a -30 a 60
rtr
taper w 0.1
hp c 0.05 n 3
lp c 0.25 n 3
Best Fitting Double Couple
Mo = 4.52e+22 dyne-cm
Mw = 4.37
Z = 118 km
Plane Strike Dip Rake
NP1 277 56 113
NP2 60 40 60
Principal Axes:
Axis Value Plunge Azimuth
T 4.52e+22 69 238
N 0.00e+00 19 84
P -4.52e+22 9 351
Moment Tensor: (dyne-cm)
Component Value
Mxx -4.15e+22
Mxy 9.43e+21
Mxz -1.45e+22
Myy 2.94e+21
Myz -1.16e+22
Mzz 3.85e+22
--- P --------
------- ------------
----------------------------
------------------------------
----------------------------------
------------------------------------
----------###########----------------#
-----########################---------##
--###############################-----##
-####################################-####
######################################-###
############### ###################----#
############### T ##################------
############## ################-------
################################--------
#############################---------
#########################-----------
--###################-------------
-----#######------------------
----------------------------
----------------------
--------------
Global CMT Convention Moment Tensor:
R T P
3.85e+22 -1.45e+22 1.16e+22
-1.45e+22 -4.15e+22 -9.43e+21
1.16e+22 -9.43e+21 2.94e+21
Details of the solution is found at
http://www.eas.slu.edu/eqc/eqc_mt/MECH.EU/20140123061505/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.
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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 -30 a 60 rtr taper w 0.1 hp c 0.05 n 3 lp c 0.25 n 3The results of this grid search from 0.5 to 19 km depth are as follow:
DEPTH STK DIP RAKE MW FIT
WVFGRD96 2.0 230 80 35 3.22 0.1016
WVFGRD96 4.0 80 60 80 3.41 0.1403
WVFGRD96 6.0 80 60 85 3.50 0.1571
WVFGRD96 8.0 300 40 -35 3.65 0.1475
WVFGRD96 10.0 75 30 -95 3.74 0.1563
WVFGRD96 12.0 270 45 -75 3.82 0.2010
WVFGRD96 14.0 270 45 -70 3.86 0.2241
WVFGRD96 16.0 270 50 -65 3.88 0.2260
WVFGRD96 18.0 270 50 -65 3.89 0.2245
WVFGRD96 20.0 270 55 -65 3.91 0.2319
WVFGRD96 22.0 270 50 -65 3.91 0.2310
WVFGRD96 24.0 50 25 45 3.94 0.2188
WVFGRD96 26.0 55 25 50 3.95 0.2330
WVFGRD96 28.0 55 50 50 3.96 0.2660
WVFGRD96 30.0 55 45 55 3.96 0.2858
WVFGRD96 32.0 55 50 50 3.96 0.2800
WVFGRD96 34.0 60 45 60 3.97 0.2706
WVFGRD96 36.0 65 45 65 3.99 0.2883
WVFGRD96 38.0 75 30 75 3.99 0.2941
WVFGRD96 40.0 75 30 75 4.10 0.3068
WVFGRD96 42.0 75 30 75 4.13 0.3006
WVFGRD96 44.0 70 30 75 4.15 0.2992
WVFGRD96 46.0 65 30 70 4.17 0.3055
WVFGRD96 48.0 60 30 65 4.18 0.3165
WVFGRD96 50.0 55 55 55 4.16 0.3261
WVFGRD96 52.0 55 55 55 4.17 0.3318
WVFGRD96 54.0 55 55 55 4.18 0.3358
WVFGRD96 56.0 55 55 55 4.19 0.3383
WVFGRD96 58.0 55 55 55 4.20 0.3466
WVFGRD96 60.0 55 40 55 4.21 0.3524
WVFGRD96 62.0 55 40 55 4.21 0.3576
WVFGRD96 64.0 55 40 55 4.22 0.3576
WVFGRD96 66.0 55 40 55 4.23 0.3655
WVFGRD96 68.0 55 40 55 4.23 0.3646
WVFGRD96 70.0 55 40 55 4.24 0.3674
WVFGRD96 72.0 55 40 55 4.25 0.3673
WVFGRD96 74.0 55 45 55 4.26 0.3670
WVFGRD96 76.0 55 40 60 4.26 0.3689
WVFGRD96 78.0 50 40 55 4.26 0.3572
WVFGRD96 80.0 55 45 55 4.27 0.3600
WVFGRD96 82.0 35 40 40 4.27 0.3598
WVFGRD96 84.0 35 40 40 4.28 0.3653
WVFGRD96 86.0 35 40 40 4.28 0.3640
WVFGRD96 88.0 35 40 40 4.29 0.3710
WVFGRD96 90.0 35 45 40 4.28 0.3676
WVFGRD96 92.0 35 45 40 4.29 0.3708
WVFGRD96 94.0 35 45 40 4.29 0.3673
WVFGRD96 96.0 50 35 50 4.30 0.3698
WVFGRD96 98.0 50 35 50 4.30 0.3721
WVFGRD96 100.0 50 35 50 4.31 0.3738
WVFGRD96 102.0 55 40 50 4.33 0.3777
WVFGRD96 104.0 55 40 50 4.33 0.3784
WVFGRD96 106.0 55 40 50 4.34 0.3852
WVFGRD96 108.0 60 40 55 4.35 0.3903
WVFGRD96 110.0 60 40 55 4.35 0.3935
WVFGRD96 112.0 60 40 55 4.36 0.3974
WVFGRD96 114.0 60 40 55 4.36 0.3985
WVFGRD96 116.0 60 40 55 4.37 0.4035
WVFGRD96 118.0 60 40 60 4.37 0.4042
WVFGRD96 120.0 60 40 60 4.38 0.4020
WVFGRD96 122.0 60 40 60 4.38 0.4035
WVFGRD96 124.0 60 40 60 4.38 0.4006
WVFGRD96 126.0 55 40 55 4.37 0.3976
WVFGRD96 128.0 55 40 55 4.38 0.3962
WVFGRD96 130.0 55 40 55 4.38 0.3943
WVFGRD96 132.0 55 40 55 4.38 0.3939
WVFGRD96 134.0 50 40 50 4.38 0.3910
WVFGRD96 136.0 50 40 50 4.38 0.3866
WVFGRD96 138.0 45 40 50 4.37 0.3853
The best solution is
WVFGRD96 118.0 60 40 60 4.37 0.4042
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 -30 a 60 rtr taper w 0.1 hp c 0.05 n 3 lp c 0.25 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 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=Thu Jan 23 09:19:34 CST 2014