Location
2013/12/29 17:08:43 41.37 14.45 10.5 4.90 Italy
Arrival Times (from USGS)
Arrival time list
Felt Map
USGS Felt map for this earthquake
USGS Felt reports page for
Focal Mechanism
SLU Moment Tensor Solution
ENS 2013/12/29 17:08:43:0 41.37 14.45 10.5 4.9 Italy
Stations used:
IV.ACER IV.AMUR IV.CAFR IV.CAMP IV.CDRU IV.CERA IV.CERT
IV.CESI IV.CESX IV.CIGN IV.CING IV.CMPR IV.FDMO IV.FRES
IV.GATE IV.GIUL IV.GUAR IV.GUMA IV.INTR IV.LAV9 IV.LNSS
IV.LPEL IV.MA9 IV.MCEL IV.MCRV IV.MELA IV.MGR IV.MIDA
IV.MIGL IV.MOCO IV.MODR IV.MRVN IV.MSAG IV.MTCE IV.MTSN
IV.NOCI IV.NRCA IV.OFFI IV.PIGN IV.POFI IV.PSB1 IV.PTQR
IV.RNI2 IV.SACR IV.SGRT IV.SIRI IV.SNAL IV.SNTG IV.T0104
IV.TERO IV.TOLF IV.TRIV MN.AQU
Filtering commands used:
cut a -10 a 90
rtr
taper w 0.1
hp c 0.02 n 3
lp c 0.07 n 3
Best Fitting Double Couple
Mo = 4.12e+23 dyne-cm
Mw = 5.01
Z = 15 km
Plane Strike Dip Rake
NP1 330 60 -70
NP2 114 36 -121
Principal Axes:
Axis Value Plunge Azimuth
T 4.12e+23 13 46
N 0.00e+00 17 140
P -4.12e+23 68 281
Moment Tensor: (dyne-cm)
Component Value
Mxx 1.90e+23
Mxy 2.06e+23
Mxz 3.58e+22
Myy 1.46e+23
Myz 2.03e+23
Mzz -3.35e+23
##############
--####################
---------###################
-------------##############
-----------------############ T ##
--------------------########## ###
-----------------------###############
#------------------------###############
#-------------------------##############
##------------ -----------##############
###----------- P ------------#############
####---------- -------------############
#####--------------------------###########
#####-------------------------##########
######-------------------------#########
#######-----------------------########
#########--------------------######-
###########-----------------###---
##############----------##----
#########################---
######################
##############
Global CMT Convention Moment Tensor:
R T P
-3.35e+23 3.58e+22 -2.03e+23
3.58e+22 1.90e+23 -2.06e+23
-2.03e+23 -2.06e+23 1.46e+23
Details of the solution is found at
http://www.eas.slu.edu/eqc/eqc_mt/MECH.IT/20131229170843/index.html
|
Preferred Solution
The preferred solution from an analysis of the surface-wave spectral amplitude radiation pattern, waveform inversion and first motion observations is
STK = 330
DIP = 60
RAKE = -70
MW = 5.01
HS = 15.0
The NDK file is 20131229170843.ndk
The waveform inversion is preferred.
Moment Tensor Comparison
The following compares this source inversion to others
| SLU |
USGSMT |
INGVTDMT |
SLU Moment Tensor Solution
ENS 2013/12/29 17:08:43:0 41.37 14.45 10.5 4.9 Italy
Stations used:
IV.ACER IV.AMUR IV.CAFR IV.CAMP IV.CDRU IV.CERA IV.CERT
IV.CESI IV.CESX IV.CIGN IV.CING IV.CMPR IV.FDMO IV.FRES
IV.GATE IV.GIUL IV.GUAR IV.GUMA IV.INTR IV.LAV9 IV.LNSS
IV.LPEL IV.MA9 IV.MCEL IV.MCRV IV.MELA IV.MGR IV.MIDA
IV.MIGL IV.MOCO IV.MODR IV.MRVN IV.MSAG IV.MTCE IV.MTSN
IV.NOCI IV.NRCA IV.OFFI IV.PIGN IV.POFI IV.PSB1 IV.PTQR
IV.RNI2 IV.SACR IV.SGRT IV.SIRI IV.SNAL IV.SNTG IV.T0104
IV.TERO IV.TOLF IV.TRIV MN.AQU
Filtering commands used:
cut a -10 a 90
rtr
taper w 0.1
hp c 0.02 n 3
lp c 0.07 n 3
Best Fitting Double Couple
Mo = 4.12e+23 dyne-cm
Mw = 5.01
Z = 15 km
Plane Strike Dip Rake
NP1 330 60 -70
NP2 114 36 -121
Principal Axes:
Axis Value Plunge Azimuth
T 4.12e+23 13 46
N 0.00e+00 17 140
P -4.12e+23 68 281
Moment Tensor: (dyne-cm)
Component Value
Mxx 1.90e+23
Mxy 2.06e+23
Mxz 3.58e+22
Myy 1.46e+23
Myz 2.03e+23
Mzz -3.35e+23
##############
--####################
---------###################
-------------##############
-----------------############ T ##
--------------------########## ###
-----------------------###############
#------------------------###############
#-------------------------##############
##------------ -----------##############
###----------- P ------------#############
####---------- -------------############
#####--------------------------###########
#####-------------------------##########
######-------------------------#########
#######-----------------------########
#########--------------------######-
###########-----------------###---
##############----------##----
#########################---
######################
##############
Global CMT Convention Moment Tensor:
R T P
-3.35e+23 3.58e+22 -2.03e+23
3.58e+22 1.90e+23 -2.06e+23
-2.03e+23 -2.06e+23 1.46e+23
Details of the solution is found at
http://www.eas.slu.edu/eqc/eqc_mt/MECH.IT/20131229170843/index.html
|
Moment
5.10e+16 N-m
Magnitude
5.1
Percent DC
77%
Depth
14.0 km
Updated
2013-12-29 20:24:44 UTC
Author
us
Catalog
us
Contributor
us
Code
us_c000ltr4_mwr
Principal Axes
Axis Value Plunge Azimuth
T 5.374 2 42
N -0.603 16 132
P -4.771 73 304
Nodal Planes
Plane Strike Dip Rake
NP1 327 49 -68
NP2 115 45 -113
|
|
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.
|
|
Location of broadband stations used for waveform inversion
|
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 -10 a 90
rtr
taper w 0.1
hp c 0.02 n 3
lp c 0.07 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 1.0 135 40 -90 4.78 0.2494
WVFGRD96 2.0 135 40 -90 4.84 0.2486
WVFGRD96 3.0 345 70 -55 4.83 0.2347
WVFGRD96 4.0 340 75 -60 4.84 0.2602
WVFGRD96 5.0 335 75 -70 4.95 0.2959
WVFGRD96 6.0 330 70 -75 4.97 0.3352
WVFGRD96 7.0 325 65 -75 4.98 0.3721
WVFGRD96 8.0 325 60 -75 4.96 0.4005
WVFGRD96 9.0 325 60 -75 4.96 0.4208
WVFGRD96 10.0 325 60 -75 4.97 0.4344
WVFGRD96 11.0 325 60 -75 4.97 0.4424
WVFGRD96 12.0 325 60 -75 4.97 0.4464
WVFGRD96 13.0 330 60 -70 4.97 0.4476
WVFGRD96 14.0 330 60 -70 4.98 0.4458
WVFGRD96 15.0 330 60 -70 5.01 0.4530
WVFGRD96 16.0 330 60 -70 5.02 0.4473
WVFGRD96 17.0 335 60 -65 5.02 0.4402
WVFGRD96 18.0 335 60 -60 5.02 0.4319
WVFGRD96 19.0 335 60 -60 5.03 0.4226
WVFGRD96 20.0 340 60 -55 5.03 0.4126
WVFGRD96 21.0 340 60 -55 5.04 0.4015
WVFGRD96 22.0 340 60 -55 5.04 0.3893
WVFGRD96 23.0 345 65 -45 5.05 0.3762
WVFGRD96 24.0 345 65 -45 5.05 0.3632
WVFGRD96 25.0 345 65 -45 5.06 0.3491
WVFGRD96 26.0 350 65 -40 5.07 0.3342
WVFGRD96 27.0 150 80 80 5.05 0.3251
WVFGRD96 28.0 150 80 75 5.05 0.3223
WVFGRD96 29.0 150 80 75 5.05 0.3196
The best solution is
WVFGRD96 15.0 330 60 -70 5.01 0.4530
The mechanism correspond to the best fit is
|
|
Figure 1. Waveform inversion focal mechanism
|
The best fit as a function of depth is given in the following figure:
|
|
Figure 2. Depth sensitivity for waveform mechanism
|
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 -10 a 90
rtr
taper w 0.1
hp c 0.02 n 3
lp c 0.07 n 3
|
|
Figure 3. Waveform comparison for selected depth. Red: observed; Blue - predicted. The time shift with respect to the model prediction is indicated. The percent of fit is also indicated.
|
|
|
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:
- 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
Velocity Model
The nnCIA used for the waveform synthetic seismograms and for the surface wave eigenfunctions and dispersion is as follows:
MODEL.01
C.It. A. Di Luzio et al Earth Plan Lettrs 280 (2009) 1-12 Fig 5. 7-8 MODEL/SURF3
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
1.5000 3.7497 2.1436 2.2753 0.500E-02 0.100E-01 0.00 0.00 1.00 1.00
3.0000 4.9399 2.8210 2.4858 0.500E-02 0.100E-01 0.00 0.00 1.00 1.00
3.0000 6.0129 3.4336 2.7058 0.500E-02 0.100E-01 0.00 0.00 1.00 1.00
7.0000 5.5516 3.1475 2.6093 0.167E-02 0.333E-02 0.00 0.00 1.00 1.00
15.0000 5.8805 3.3583 2.6770 0.167E-02 0.333E-02 0.00 0.00 1.00 1.00
6.0000 7.1059 4.0081 3.0002 0.167E-02 0.333E-02 0.00 0.00 1.00 1.00
8.0000 7.1000 3.9864 3.0120 0.167E-02 0.333E-02 0.00 0.00 1.00 1.00
0.0000 7.9000 4.4036 3.2760 0.167E-02 0.333E-02 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:
DATE=Mon Dec 30 08:16:21 CST 2013
Last Changed 2013/12/29
