Transcript ISOLA-GUI: A Matlab GUI for Moment Tensor Retrieval

NEW VERSION OF ISOLA SOFTWARE TO
INVERT FULL WAVEFORMS INTO SEISMIC
SOURCE MODELS
Efthimios Sokos 1) and Jiri Zahradnik 2)
1) University
of Patras, Greece
2) Charles University in Prague, Czech Republic
http://seismo.geology.upatras.gr/isola
ISOLated Asperities
Time
Hypocentre
Main asperity
• Input waveforms in SAC, GCF, SEISAN, PITSA
• Calculations in Fortran – GUI in Matlab
• Graphical User Interface in Matlab (incl. GMT, PS, Google
Earth, Ascii and other output formats).
Theory - formulation
3
3
ui (t )  M pq  Gip, q
p 1 q 1
M pq  ai M
i
pq
6
6
ui (t )   a j ( M pqj  Gip,q )   a j Ei j (t )
j
  a4  a6

M 
a1
 a
2

p
j 1
q
a1
 a5  a6
 a3


 a3

a 4  a5  a 6 
a2
u=Ea
Theory – waveform match
    (ui (t )  a j Ei j ) 2 dt
i
var red  1 
Corr 

2
u
 (t )dt
 us
u s
2 2
CN 
max ( wi )
i 1,... 6
min ( wi )
i 1,... 6
misfit
variance reduction
correlation
corr  varred
condition number
(w… sing. values
of the design matrix E)
Theory – computer modes
a1, a2, …. a6
full MT
a1, a2, …. a5 (and a6=0)
deviatoric MT
a1, a2, …. a5 (and det M =0)
DC-constrained MT
,
moment-rate time function
delta or triangle
Green fct and elementary seismograms
DW method,
spatiotemporal grid search
multiple point sources (MPS)
iterative deconvolution
Previous summary
ISOLA status
http://seismo.geology.upatras.gr/isola/
•
•
•
•
Visitor map July – August 2012
First release 2004
Currently ~ 100 registered users
Routine use Univ. Patras – Greece (reporting to EMSC)
Central and South America seminar on ISOLA use. Costa Rica &
IASPEI, 2011 – 15 participants
ISOLA - New Features
• Forward
simulation
– Full MT, deviatoric
and DC options
– Useful for
preparation of
synthetic data
– Useful for a
posteriori check
of inversion (e.g.
for station not
used in inversion)
ISOLA - New Features
• Forward
simulation
wrong !
Gallovic and Zahradnik, JGR 2011
– Synthetic tests
revealed
possible
artifacts for
bilateral
ruptures
ISOLA - New Features
• Choosing the lowfrequency range
for MT inversion
by S/N analysis
(high-frequency
limitation is due to
epicentral distance)
- each station
may have a
different freq.
range !
ISOLA - New Features
Variance Reduction (VR)
• Solution
Quality
VR . SN / CN
Signal-to-Noise ratio
in analyzed frequency
band (SN)
Source-station configuration,
frequency range and crustal model
=> Condition Number (CN)
Plot of Vp, Vs CLDRmodif1.da
0
Vp
Vs
10
Depth (km)
20
30
40
50
60
1
2
3
4
5
6
Velocity (km/sec)
7
8
9
ISOLA - New Features
• Uncertainty
assessment
- 6D error ellipsoid is
numerically
constructed
- Covers effect of the
source-station
config. and freq.
range
Zahradnik and Custodio, BSSA 2012
ISOLA - New Features
• Uncertainty
assessment
- Semi-automatic
determination of
strike/dip/rake
ranges
- Also available for
ISO (=VOL) range
ISOLA - New Features
• Uncertainty
assessment
Does not need waveforms, thus enabling mapping of expected MT resolvability
without any earthquake observation [= seismic network design].
Zahradnik and Custodio, BSSA 2012
ISOLA - New Features
• Time-function (for
fixed MT)
- calculated by nonnegative least
squares
-
1 or 2 source option
- each source may
have a different MT
ISOLA - New Features
• Time-function
(for fixed MT)
2009 06 26
Mw 4.9 (AUTH)
near Columbo
volcano
Aegean Sea
ISO ~ 50%
each source may
have a different
MT
a special case:
different time
functions of the
DC and ISO
components
of the same
source
ISO
DC
Krizova, Zahradnik
and Kiratzi, BSSA
submitted
ISOLA - New Features
• Automated
removal of
instrumental
disturbances
often observed
on BB records
(e.g. due to tilt)
• Special GUI based on
Zahradnik & Plesinger,
BSSA 2005 and 2010
• Corrected records are
saved for further use in
inversion
ISOLA - New Features
blue: distorted raw displacement record
red: corrected record
• Automated
removal of
instrumental
disturbances
often observed
on BB records
(e.g. due to tilt)
• Special GUI based on
Zahradnik & Plesinger,
BSSA 2005 and 2010
• Corrected records are
saved for further use in
inversion
ISOLA - New Features
• Rotate
horizontal
components
helpful with
acceleration data
often not
recorded in N, E
-visual control
-data saved for
further use in
inversion
ISOLA - New Features
• Graphic
output
summary
-
-
-
Easy display of
MT’s on users’
web pages
Easily
converted to
various graphic
formats,
Easily adapted
to user needs
ISOLA - New Features
______________________________________
University of Patras
Seismological Laboratory
______________________________________
======================================
======= Moment Tensor Solution =======
======================================
Hypocenter Solution (UPSL)
Origin Time : 20081023 03:25:13.83
Lat: 38.1438
Lon: 22.5817
Depth (km) : 7.5
Mw : 4.1
Moment Tensor (Nm): Exponent 10**15
Mrr
Mtt
Mpp
-0.928
1.113 -0.186
Mrt
Mrp
Mtp
-0.963 -0.236 -0.589
VOL (%)
: 0
DC (%)
: 81.5
CLVD (%)
: 18.5
Best Double Couple: Mo= 1.548e+015
NP1:
Strike
Dip
Rake
319
34
-43
NP2:
Strike
Dip
Rake
86
68
-116
======================================
Centroid Solution
Centroid Time : +1.95 (sec) relative to
origin time
Centroid Lat: 38.1438
Lon: 22.5817
Centroid Depth : 7
======================================
No of Stations: 5
(DSF-GUR-LTK-EFP-UPR)
Freq band (Hz)
0.05-0.08 tapered 0.04-0.05 and 0.08-0.09
Variance Reduction (%): 84
Nm
#######
#################
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--------------------#########
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----------- P -------------######
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----------------------------#####---------------------------#---########-------------########---############################--############################--###########################-#######
################### T #############
###
###########
#######
Moment Tensor Solution computed using ISOLA
http://seismo.geology.upatras.gr/isola/
University of Patras, Geology Department
Seismological Laboratory
http://seismo.geology.upatras.gr
• Text
summary of
the
inversion
-Easy MT
reporting via
e-mail
-User creates
his/her header
and footer
ISOLA - New Features
• Spatiotemporal
evolution for
extended sources
- Graphic output of the
moments (circle radii)
and rupture times
(colors)
- ASCII text output (e.g.
for GPS forward
modeling)
LON
21.9118
21.9766
………….
LAT
38.4352
38.4862
………..
Time
-4.6
-4.7
……
Moment (Nm)
1.68e+018
1.68e+017
………
Application – Tohoku, Japan 2011 (Mw 9.0)
near-regional stations
period
10-100 seconds
testing ISOLA in an
‘extreme’ case
Application – Van, Turkey 2011 (Mw 7.1)
regional stations
period
100-200 seconds
a single-source
approximation
Zahradnik and Sokos,
report to EMSC 7 days after earthquake
Application – Van, Turkey 2011 (Mw 7.1)
near-regional stations
10-20 seconds
seeking major subevent
The deviatoric inversion produced
a very large (> 50%) spurious non-DC component due to the finite-extent source effect.
Thus the major subevent had to be found by the DC-constrained inversion.
Van earthquake
near-regional stations
6-20 seconds:
reveal at least 3 slip episodes
Uncertainty =
other possible scenarios
fitting data
equally well
17
18
19
Application - L’Aquila 2009 (Mw 6.3)
ISOLA
(green circles)
validated
through
comparison
with
TSVD
slip inversion
(color)
near stations
periods 3-16 seconds
Gallovic and Zahradnik, JGR 2012
Application – Efpalio 2010 sequence,
Greece (30 events Mw 2.5 to 5.3)
near-regional stations
periods dependent on Mw
(basically above 8 seconds)
Result: Complex system of shallow normal
and strike-slip faults complement the
previously known gently dipping structures
under Corinth Gulf.
Sokos et al., Tectonophysics 2012
Application – local event (Mw 0.2)
local stations (up to 3km)
depth 1 km
periods 0.4 – 0.5 s
MT inversion possible
down to relatively short periods
thanks to proximity of the stations
(for which the existing structural model
is sufficient)
Benetatos, Malek, Verga
J. of Seismology, submitted
Conclusion - why to use ISOLA
• Compact package (“all in one”): From raw records
up to publication-quality figures
• Routine tool for point source inversion (regional to
local distances), research tool for complex finiteextent sources
• Tested on events Mw 0.2 to 9.0
• Windows (most user friendly), Linux and MacOs
• All source codes provided to users
• Continuous e-mail consultations
• Continuing software development & Manual and
Web page
Thank you for your attention !
ISOLA - New Features - Overview
• Inversion
–
–
–
–
–
Choosing suitable frequency range by S/N analysis
Different frequency range for different stations
Non-negative moment-rate time function retrieval (for fixed MT)
Removal of instrumental disturbances
Forward simulation tool to design synthetic tests
– Spatiotemporal visualization of source complexity
– Different crustal models for different source-station paths
• Uncertainty estimation
– Strike, dip, rake and ISO ranges
– Seismic network MT resolvability
– Validation of spatiotemporal scenarios by perturbations