2014/03/08 15:12:32 41.48 19.43 10.0 4.5 Albania
USGS Felt map for this earthquake
USGS/SLU Moment Tensor Solution
ENS 2014/03/08 15:12:32:0 41.48 19.43 10.0 4.5 Albania
Stations used:
BS.PLD HL.KEK HT.AGG HT.ALN HT.FNA HT.HORT HT.KNT HT.LIT
HT.LKD2 HT.PAIG HT.SIGR HT.SRS HT.XOR MN.VTS RO.ARR RO.BZS
RO.LOT RO.VOIR SJ.BBLS SJ.FRGS
Filtering commands used:
cut a -20 a 210
rtr
taper w 0.1
hp c 0.02 n 3
lp c 0.06 n 3
Best Fitting Double Couple
Mo = 2.11e+22 dyne-cm
Mw = 4.15
Z = 27 km
Plane Strike Dip Rake
NP1 161 70 94
NP2 330 20 80
Principal Axes:
Axis Value Plunge Azimuth
T 2.11e+22 65 77
N 0.00e+00 3 339
P -2.11e+22 25 248
Moment Tensor: (dyne-cm)
Component Value
Mxx -2.26e+21
Mxy -5.17e+21
Mxz 4.99e+21
Myy -1.11e+22
Myz 1.55e+22
Mzz 1.34e+22
--------------
----###########-------
------################------
-------##################-----
---------####################-----
-----------####################-----
------------######################----
-------------#######################----
-------------#######################----
---------------########### #########----
---------------########### T #########----
----------------########## #########----
-----------------#####################----
---- ---------#####################---
---- P ----------####################---
--- -----------###################--
-----------------#################--
-----------------###############--
----------------#############-
-----------------##########-
----------------######
--------------
Global CMT Convention Moment Tensor:
R T P
1.34e+22 4.99e+21 -1.55e+22
4.99e+21 -2.26e+21 5.17e+21
-1.55e+22 5.17e+21 -1.11e+22
Details of the solution is found at
http://www.eas.slu.edu/eqc/eqc_mt/MECH.EU/20140308151232/index.html
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STK = 330
DIP = 20
RAKE = 80
MW = 4.15
HS = 27.0
The NDK file is 20140308151232.ndk The waveform inversion is preferred.
The following compares this source inversion to others
USGS/SLU Moment Tensor Solution
ENS 2014/03/08 15:12:32:0 41.48 19.43 10.0 4.5 Albania
Stations used:
BS.PLD HL.KEK HT.AGG HT.ALN HT.FNA HT.HORT HT.KNT HT.LIT
HT.LKD2 HT.PAIG HT.SIGR HT.SRS HT.XOR MN.VTS RO.ARR RO.BZS
RO.LOT RO.VOIR SJ.BBLS SJ.FRGS
Filtering commands used:
cut a -20 a 210
rtr
taper w 0.1
hp c 0.02 n 3
lp c 0.06 n 3
Best Fitting Double Couple
Mo = 2.11e+22 dyne-cm
Mw = 4.15
Z = 27 km
Plane Strike Dip Rake
NP1 161 70 94
NP2 330 20 80
Principal Axes:
Axis Value Plunge Azimuth
T 2.11e+22 65 77
N 0.00e+00 3 339
P -2.11e+22 25 248
Moment Tensor: (dyne-cm)
Component Value
Mxx -2.26e+21
Mxy -5.17e+21
Mxz 4.99e+21
Myy -1.11e+22
Myz 1.55e+22
Mzz 1.34e+22
--------------
----###########-------
------################------
-------##################-----
---------####################-----
-----------####################-----
------------######################----
-------------#######################----
-------------#######################----
---------------########### #########----
---------------########### T #########----
----------------########## #########----
-----------------#####################----
---- ---------#####################---
---- P ----------####################---
--- -----------###################--
-----------------#################--
-----------------###############--
----------------#############-
-----------------##########-
----------------######
--------------
Global CMT Convention Moment Tensor:
R T P
1.34e+22 4.99e+21 -1.55e+22
4.99e+21 -2.26e+21 5.17e+21
-1.55e+22 5.17e+21 -1.11e+22
Details of the solution is found at
http://www.eas.slu.edu/eqc/eqc_mt/MECH.EU/20140308151232/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 210 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 0.5 340 40 -90 3.76 0.2281
WVFGRD96 1.0 345 45 -90 3.81 0.2429
WVFGRD96 2.0 165 45 -90 3.89 0.2870
WVFGRD96 3.0 170 45 -90 3.96 0.2913
WVFGRD96 4.0 0 45 -85 3.98 0.2362
WVFGRD96 5.0 140 90 -30 3.92 0.1959
WVFGRD96 6.0 305 55 -15 3.92 0.1958
WVFGRD96 7.0 155 90 75 3.91 0.2123
WVFGRD96 8.0 155 90 80 3.99 0.2301
WVFGRD96 9.0 275 5 30 3.99 0.2572
WVFGRD96 10.0 290 10 45 4.00 0.2837
WVFGRD96 11.0 300 10 55 4.01 0.3088
WVFGRD96 12.0 295 15 50 4.02 0.3313
WVFGRD96 13.0 305 15 60 4.03 0.3543
WVFGRD96 14.0 310 15 65 4.04 0.3737
WVFGRD96 15.0 315 15 70 4.05 0.3921
WVFGRD96 16.0 315 15 70 4.06 0.4081
WVFGRD96 17.0 315 20 70 4.07 0.4222
WVFGRD96 18.0 315 20 70 4.08 0.4355
WVFGRD96 19.0 320 20 75 4.09 0.4464
WVFGRD96 20.0 320 20 75 4.09 0.4564
WVFGRD96 21.0 320 20 75 4.11 0.4632
WVFGRD96 22.0 325 20 75 4.11 0.4697
WVFGRD96 23.0 325 20 75 4.12 0.4757
WVFGRD96 24.0 325 20 75 4.13 0.4795
WVFGRD96 25.0 325 20 75 4.13 0.4820
WVFGRD96 26.0 330 20 80 4.14 0.4840
WVFGRD96 27.0 330 20 80 4.15 0.4841
WVFGRD96 28.0 325 25 75 4.15 0.4833
WVFGRD96 29.0 160 70 95 4.16 0.4819
WVFGRD96 30.0 325 25 75 4.16 0.4788
WVFGRD96 31.0 160 65 90 4.17 0.4756
WVFGRD96 32.0 345 25 95 4.18 0.4711
WVFGRD96 33.0 345 25 95 4.18 0.4659
WVFGRD96 34.0 355 25 105 4.19 0.4606
WVFGRD96 35.0 355 25 105 4.20 0.4540
WVFGRD96 36.0 355 25 105 4.20 0.4468
WVFGRD96 37.0 155 65 80 4.22 0.4399
WVFGRD96 38.0 155 65 80 4.22 0.4319
WVFGRD96 39.0 155 70 80 4.22 0.4239
WVFGRD96 40.0 155 75 85 4.36 0.4122
WVFGRD96 41.0 155 70 80 4.37 0.4051
WVFGRD96 42.0 155 70 80 4.37 0.3987
WVFGRD96 43.0 155 70 80 4.38 0.3918
WVFGRD96 44.0 155 70 80 4.38 0.3845
WVFGRD96 45.0 155 65 75 4.39 0.3776
WVFGRD96 46.0 155 65 75 4.40 0.3703
WVFGRD96 47.0 155 65 75 4.40 0.3626
WVFGRD96 48.0 155 65 75 4.41 0.3547
WVFGRD96 49.0 155 65 75 4.41 0.3464
The best solution is
WVFGRD96 27.0 330 20 80 4.15 0.4841
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 210 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 18:01:20 CST 2014