SPICE Research and Training Workshop III, July 22-28, Kinsale, Ireland Seismic wave Propagation and Imaging in Complex media: a European network Sara Di Carli Early Stage Researcher Host Institution: ENS Paris Place of Origin: Roma, Italy Appointment Time: November 2004 Project: Dynamic inversion of the 2000 Tottori Earthquake. Task Groups: TG Local scale Cooperation: Caroline Holden (ENS Paris)

SPICE Research and Training Workshop III, July 22-28, Kinsale, Ireland The Tottori earthquake (M 6.8, Japan, 2000) PROBLEM - many kinematic models fit the observed data well - not all of them are consistent with earthquake source dynamics Can earthquake dynamics distinguish among these models? METHOD Dynamic rupture inversion using : - the slip-weakening friction law - slip distributions controlled by few elliptical patches Project Scope

SPICE Research and Training Workshop III, July 22-28, Kinsale, Ireland No surface rupture observation M w 6.6~6.8 Pure left-lateral strike slip event Hypocentral depth poorly constrained Tottori accelerograms have absolute time We study the location of hypocentre directly from raw records The 2000 Western Tottori (Japan) earthquake

SPICE Research and Training Workshop III, July 22-28, Kinsale, Ireland Example of velocity data processing Time measured w/r to origin time P S Data integrated and filtered between Hz We relocate the hypocentre close to 14 km depth

SPICE Research and Training Workshop III, July 22-28, Kinsale, Ireland Kinematic inversion of Tottori earthquake Low slip around the hypocentre Slip increases towards the upper northern edge of the fault Kinematic slip distribution Velocity Waveform fitting The diagonal zone controls the waveform (probably stopping phase) EW component T05 S02 OK015 T07 OK05 OK04 S15 S03 T06 T08 T09 Good fit at all nearfield stations (misfit=3.4)

SPICE Research and Training Workshop III, July 22-28, Kinsale, Ireland The initial stress field Rupture is forced to start from an asperity located at 18 km in depth Then we modify the elliptical slip distribution until the rupture propagates and the seismograms are fitted Slip rate Slip Stress Dynamic inversion of Tottori t=2s t=4s t=6s t=8s

SPICE Research and Training Workshop III, July 22-28, Kinsale, Ireland Main Results Velocity waveforms fit observations less well than the kinematic model, misfit=5.9 (fit is 50% less good) For each station both amplitude and arrival phases match satisfactorily T05 S04 OK015 T07 OK05 OK04 S15 S03 T06 T08 T09 Velocity Waveform fitting for EW component

SPICE Research and Training Workshop III, July 22-28, Kinsale, Ireland Influence of different rupture patches S15 T09 Final slip distribution NS component The stopping phase (red) exerts the primary control on the waveform real synth real synth

SPICE Research and Training Workshop III, July 22-28, Kinsale, Ireland Outlook Two approaches to study the propagation of the Tottori earthquake Non linear kinematic inversion: good wavefits control by a diagonal stopping phase Dynamic rupture inversion: good amplitude and arrival phase control by an horizontal stopping phase In progress: dynamic inversion with a slip distribution controlled by 2 ellipsoidal patches