2010/07/09 22:15:11 41.242 19.939 20.0 4.80 Albania
USGS Felt map for this earthquake
USGS/SLU Moment Tensor Solution
ENS 2010/07/09 22:15:11:2 41.24 19.94 20.0 4.8 Albania
Stations used:
GE.TIRR HT.FNA HT.GRG HT.HORT HT.KNT HT.LIT HT.SOH HT.SRS
HT.THE HT.XOR MN.DIVS MN.PDG MN.VTS RO.BZS RO.DEV RO.LOT
Filtering commands used:
hp c 0.02 n 3
lp c 0.10 n 3
Best Fitting Double Couple
Mo = 1.00e+23 dyne-cm
Mw = 4.60
Z = 27 km
Plane Strike Dip Rake
NP1 321 47 105
NP2 120 45 75
Principal Axes:
Axis Value Plunge Azimuth
T 1.00e+23 79 305
N 0.00e+00 11 131
P -1.00e+23 1 41
Moment Tensor: (dyne-cm)
Component Value
Mxx -5.66e+22
Mxy -5.10e+22
Mxz 9.15e+21
Myy -4.00e+22
Myz -1.58e+22
Mzz 9.66e+22
--------------
----------------------
#########----------------- P
###############------------
####################--------------
#######################-------------
-#########################------------
--###########################-----------
---###########################----------
----############## ###########----------
-----############# T ############---------
------############ #############--------
-------############################-------
--------##########################------
----------########################------
-----------######################-----
-------------###################----
----------------###############-##
-----------------------------#
---------------------------#
----------------------
--------------
Global CMT Convention Moment Tensor:
R T P
9.66e+22 9.15e+21 1.58e+22
9.15e+21 -5.66e+22 5.10e+22
1.58e+22 5.10e+22 -4.00e+22
Details of the solution is found at
http://www.eas.slu.edu/Earthquake_Center/MECH.NA/20100709221511/index.html
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STK = 120
DIP = 45
RAKE = 75
MW = 4.60
HS = 27.0
The waveform inversion is preferred.
The following compares this source inversion to others
USGS/SLU Moment Tensor Solution
ENS 2010/07/09 22:15:11:2 41.24 19.94 20.0 4.8 Albania
Stations used:
GE.TIRR HT.FNA HT.GRG HT.HORT HT.KNT HT.LIT HT.SOH HT.SRS
HT.THE HT.XOR MN.DIVS MN.PDG MN.VTS RO.BZS RO.DEV RO.LOT
Filtering commands used:
hp c 0.02 n 3
lp c 0.10 n 3
Best Fitting Double Couple
Mo = 1.00e+23 dyne-cm
Mw = 4.60
Z = 27 km
Plane Strike Dip Rake
NP1 321 47 105
NP2 120 45 75
Principal Axes:
Axis Value Plunge Azimuth
T 1.00e+23 79 305
N 0.00e+00 11 131
P -1.00e+23 1 41
Moment Tensor: (dyne-cm)
Component Value
Mxx -5.66e+22
Mxy -5.10e+22
Mxz 9.15e+21
Myy -4.00e+22
Myz -1.58e+22
Mzz 9.66e+22
--------------
----------------------
#########----------------- P
###############------------
####################--------------
#######################-------------
-#########################------------
--###########################-----------
---###########################----------
----############## ###########----------
-----############# T ############---------
------############ #############--------
-------############################-------
--------##########################------
----------########################------
-----------######################-----
-------------###################----
----------------###############-##
-----------------------------#
---------------------------#
----------------------
--------------
Global CMT Convention Moment Tensor:
R T P
9.66e+22 9.15e+21 1.58e+22
9.15e+21 -5.66e+22 5.10e+22
1.58e+22 5.10e+22 -4.00e+22
Details of the solution is found at
http://www.eas.slu.edu/Earthquake_Center/MECH.NA/20100709221511/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:
hp c 0.02 n 3 lp c 0.10 n 3The results of this grid search from 0.5 to 19 km depth are as follow:
DEPTH STK DIP RAKE MW FIT
WVFGRD96 0.5 215 45 -95 3.88 0.2143
WVFGRD96 1.0 35 45 -90 3.95 0.2324
WVFGRD96 2.0 35 45 -90 4.09 0.3073
WVFGRD96 3.0 40 45 -80 4.15 0.2728
WVFGRD96 4.0 230 70 -45 4.10 0.1989
WVFGRD96 5.0 275 30 -5 4.06 0.2193
WVFGRD96 6.0 275 35 -5 4.09 0.2543
WVFGRD96 7.0 275 35 -10 4.10 0.2852
WVFGRD96 8.0 275 30 -10 4.18 0.3104
WVFGRD96 9.0 270 30 -15 4.21 0.3406
WVFGRD96 10.0 275 35 -10 4.23 0.3672
WVFGRD96 11.0 275 35 -10 4.25 0.3909
WVFGRD96 12.0 275 35 -10 4.27 0.4111
WVFGRD96 13.0 280 35 15 4.30 0.4312
WVFGRD96 14.0 280 40 25 4.34 0.4504
WVFGRD96 15.0 280 40 30 4.37 0.4699
WVFGRD96 16.0 280 45 35 4.41 0.4903
WVFGRD96 17.0 280 45 35 4.43 0.5082
WVFGRD96 18.0 280 45 40 4.45 0.5238
WVFGRD96 19.0 130 40 85 4.49 0.5445
WVFGRD96 20.0 125 40 80 4.51 0.5627
WVFGRD96 21.0 125 40 80 4.53 0.5758
WVFGRD96 22.0 125 40 75 4.54 0.5899
WVFGRD96 23.0 125 40 75 4.55 0.6008
WVFGRD96 24.0 125 40 75 4.56 0.6092
WVFGRD96 25.0 125 40 75 4.57 0.6150
WVFGRD96 26.0 120 45 75 4.59 0.6186
WVFGRD96 27.0 120 45 75 4.60 0.6203
WVFGRD96 28.0 120 45 75 4.61 0.6195
WVFGRD96 29.0 125 45 80 4.62 0.6141
The best solution is
WVFGRD96 27.0 120 45 75 4.60 0.6203
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 componnet is plotted to the same scale and peak amplitudes are indicated by the numbers to the left of each trace. The number in black at the rightr of each predicted traces 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 bandpass filter used in the processing and for the display was
hp c 0.02 n 3 lp c 0.10 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. |
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 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
Here we tabulate the reasons for not using certain digital data sets
The following stations did not have a valid response files:
DATE=Sat Jul 10 07:29:12 CDT 2010