2014/03/08 15:06:32 41.51 19.44 10.0 4.3 Albania
USGS Felt map for this earthquake
USGS/SLU Moment Tensor Solution
ENS 2014/03/08 15:06:32:0 41.51 19.44 10.0 4.3 Albania
Stations used:
BS.PLD HT.AGG HT.ALN HT.GRG HT.HORT HT.KNT HT.LIT HT.LKD2
HT.PAIG HT.SRS MN.TIR RO.ARR RO.BZS RO.VOIR SJ.BBLS SJ.FRGS
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 = 1.22e+22 dyne-cm
Mw = 3.99
Z = 29 km
Plane Strike Dip Rake
NP1 155 70 60
NP2 34 36 144
Principal Axes:
Axis Value Plunge Azimuth
T 1.22e+22 55 27
N 0.00e+00 28 166
P -1.22e+22 19 267
Moment Tensor: (dyne-cm)
Component Value
Mxx 3.17e+21
Mxy 1.08e+21
Mxz 5.29e+21
Myy -9.94e+21
Myz 6.43e+21
Mzz 6.77e+21
##############
--####################
-----######################-
------#######################-
--------#######################---
---------############ #########---
-----------########### T #########----
------------########### #########-----
-------------######################-----
--------------######################------
--- ---------#####################------
--- P ----------###################-------
--- -----------##################-------
-----------------################-------
------------------##############--------
------------------############--------
------------------#########---------
------------------######----------
------------------##----------
----------------###---------
#-----############----
##############
Global CMT Convention Moment Tensor:
R T P
6.77e+21 5.29e+21 -6.43e+21
5.29e+21 3.17e+21 -1.08e+21
-6.43e+21 -1.08e+21 -9.94e+21
Details of the solution is found at
http://www.eas.slu.edu/eqc/eqc_mt/MECH.EU/20140308150632/index.html
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STK = 155
DIP = 70
RAKE = 60
MW = 3.99
HS = 29.0
The NDK file is 20140308150632.ndk The waveform inversion is preferred.
The following compares this source inversion to others
USGS/SLU Moment Tensor Solution
ENS 2014/03/08 15:06:32:0 41.51 19.44 10.0 4.3 Albania
Stations used:
BS.PLD HT.AGG HT.ALN HT.GRG HT.HORT HT.KNT HT.LIT HT.LKD2
HT.PAIG HT.SRS MN.TIR RO.ARR RO.BZS RO.VOIR SJ.BBLS SJ.FRGS
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 = 1.22e+22 dyne-cm
Mw = 3.99
Z = 29 km
Plane Strike Dip Rake
NP1 155 70 60
NP2 34 36 144
Principal Axes:
Axis Value Plunge Azimuth
T 1.22e+22 55 27
N 0.00e+00 28 166
P -1.22e+22 19 267
Moment Tensor: (dyne-cm)
Component Value
Mxx 3.17e+21
Mxy 1.08e+21
Mxz 5.29e+21
Myy -9.94e+21
Myz 6.43e+21
Mzz 6.77e+21
##############
--####################
-----######################-
------#######################-
--------#######################---
---------############ #########---
-----------########### T #########----
------------########### #########-----
-------------######################-----
--------------######################------
--- ---------#####################------
--- P ----------###################-------
--- -----------##################-------
-----------------################-------
------------------##############--------
------------------############--------
------------------#########---------
------------------######----------
------------------##----------
----------------###---------
#-----############----
##############
Global CMT Convention Moment Tensor:
R T P
6.77e+21 5.29e+21 -6.43e+21
5.29e+21 3.17e+21 -1.08e+21
-6.43e+21 -1.08e+21 -9.94e+21
Details of the solution is found at
http://www.eas.slu.edu/eqc/eqc_mt/MECH.EU/20140308150632/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 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 1.0 330 80 -10 3.53 0.2710
WVFGRD96 2.0 330 80 -10 3.63 0.3508
WVFGRD96 3.0 150 90 10 3.68 0.3993
WVFGRD96 4.0 150 90 5 3.72 0.4199
WVFGRD96 5.0 330 90 -5 3.74 0.4203
WVFGRD96 6.0 145 90 5 3.75 0.4189
WVFGRD96 7.0 145 85 5 3.78 0.4213
WVFGRD96 8.0 145 80 0 3.81 0.4299
WVFGRD96 9.0 310 75 -55 3.87 0.4294
WVFGRD96 10.0 310 75 -55 3.88 0.4587
WVFGRD96 11.0 310 75 -55 3.89 0.4818
WVFGRD96 12.0 305 70 -55 3.90 0.5012
WVFGRD96 13.0 305 70 -50 3.89 0.5194
WVFGRD96 14.0 140 85 70 3.92 0.5326
WVFGRD96 15.0 140 85 65 3.92 0.5480
WVFGRD96 16.0 140 80 70 3.94 0.5606
WVFGRD96 17.0 145 75 75 3.93 0.5719
WVFGRD96 18.0 145 75 75 3.94 0.5828
WVFGRD96 19.0 300 45 30 3.90 0.5945
WVFGRD96 20.0 300 45 30 3.91 0.6033
WVFGRD96 21.0 150 65 55 3.96 0.6179
WVFGRD96 22.0 150 65 55 3.96 0.6247
WVFGRD96 23.0 155 65 50 3.96 0.6325
WVFGRD96 24.0 155 65 55 3.97 0.6385
WVFGRD96 25.0 155 65 60 3.97 0.6425
WVFGRD96 26.0 155 65 60 3.98 0.6450
WVFGRD96 27.0 155 70 55 3.98 0.6455
WVFGRD96 28.0 155 70 60 3.99 0.6481
WVFGRD96 29.0 155 70 60 3.99 0.6493
WVFGRD96 30.0 155 70 60 4.00 0.6474
WVFGRD96 31.0 160 70 65 4.00 0.6439
WVFGRD96 32.0 160 70 65 4.00 0.6413
WVFGRD96 33.0 160 70 65 4.01 0.6369
WVFGRD96 34.0 160 70 65 4.02 0.6296
WVFGRD96 35.0 165 70 70 4.01 0.6214
WVFGRD96 36.0 165 70 75 4.02 0.6137
WVFGRD96 37.0 165 70 75 4.02 0.6062
WVFGRD96 38.0 260 15 20 4.05 0.5954
WVFGRD96 39.0 260 15 20 4.04 0.5909
WVFGRD96 40.0 255 10 15 4.19 0.5865
WVFGRD96 41.0 250 10 10 4.20 0.5808
WVFGRD96 42.0 245 10 5 4.20 0.5747
WVFGRD96 43.0 245 10 5 4.20 0.5690
WVFGRD96 44.0 245 10 5 4.21 0.5629
WVFGRD96 45.0 240 10 0 4.21 0.5568
WVFGRD96 46.0 235 10 -5 4.21 0.5512
WVFGRD96 47.0 235 10 -5 4.22 0.5447
WVFGRD96 48.0 230 10 -10 4.22 0.5395
WVFGRD96 49.0 230 10 -10 4.22 0.5332
The best solution is
WVFGRD96 29.0 155 70 60 3.99 0.6493
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 180 rtr taper w 0.1 hp c 0.02 n 3 lp c 0.06 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=Sat Mar 8 18:02:07 CST 2014