Waveform inversion for moment tensors and (multiple) point-source models
Day 1
====
Theory 1: Moment tensor MT; source time function, Green's tensor; synthetic
seismogram. Elementary mechanism and elementary seismogram. MT and acoefficients.
Practice 1: Green's functions by discrete-wavenumber method (coordinate origin,
source and station positions, temporal window, spatial periodicity, maximum
computed frequency, filters); example Pascal
Practice 2: Crustal models (velocities and Q factors, multiple 1D models to simulate a
3D crustal structure)
Practice 3: Defining trial positions for the source optimization (below epicenter,);
example Pascal
Practice 4: ISOLA – forward solution
Day 2
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Practice 5: Converting SAC and GCF formats to ASCII (start time, origin time,
checking absolute time through first-motion residuals); GCF example Pascal; SAC
example ???
Practice 6: Correcting records for instrument response (poles and zeros, broad band,
strong motion, instrumental noise, instrumental disturbances); example Pascal
Practice 7: Selecting frequency window of interest (natural noise, instrumental noise,
Green's functions reliability, re-sampling waveforms)
Day 3
====
Theory 2: Waveform inversion for single point-source MT (inverse problem
formulation, least-square solution, variance reduction, well and poorly constrained
problems, MT inversion from few stations)
Theory 3: Deviatoric and full moment tensor (MT decomposition, poorly constrained
non-DC parts, uncertainties)
Practice 8: Selecting stations (station weights, deselecting wrong data, deselecting
stations for jackknifing tests)
Practice 9: Waveform correlation for trial positions; INV1.dat plot; example Pascal
For Pascal we need data in SAC == make form ASCII we don’t have SAC !!!!!
Practice 10: Checking first-motion polarities, comparing with independent solutions
Day 4
====
Theory 4: Multiple point sources (double events, complex events, slip distribution on
a fault, preventing bias through fixing MT; slip inversion artifacts); paper Lefkada,
Andravida, Aquila, Tohoku
Practice 11: Defining trial positions for the source optimization (along lines, planes);
example Andravida, Tohoku
Theory 5: Identifying fault plane (H-C method, uncertainties); paper Leonidio;
example Efpalio (table 1. and 2).
DAY 5
=====
Repetition, training, miscellaneous
---------------------------------------Additional:
Long-period disturbances (examples OBS stations)
Slip inversion artifacts (synthetic bilateral model)
MT uncertainty (examples Portugal)
Presenting results. (plotting obs versus synt seismograms; mapping correlation
isolines, plotting DC and full MT beachballs, plotting correlation versus trial source
position, plotting time function, generating e-mail messages)
16. Case study 1: Movri-Mountain, Greece Mw 6.3, 2008 in regional network
(centroid, hypocenter, fault plane, slip distribution)
17. Case study 2: A Mw~3 earthquake in near-regional network (problems with noise)
18. Case study 3: Efpalio, Greece earthquake sequence 2010 (two Mw~5 mainshocks,
30 aftershocks with MT, many others without MT, problematic identification of the
fault plane)
19. Case study 4: Miyagi, Japan Mw~7.2, 2008 (near fault accelerograph stations well
constraining the slip distribution, bias between source finiteness and non-DC
components)
20. Training: Each participant inverts his/her own waveforms (get ready your
waveforms, origin and start times, poles and zeros, crustal models, station
coordinates, maybe also results of the hypocenter location, polarities, alternative
solutions by other agencies).