www.spice-rtn.orgMid-Term Review Meeting, February 13-14, Tutzing

Seismic wave Propagation and Imaging in Complex media: a European network

Local scale group

Responsable: Martin Mai, ETH Zürich

Speaker: Raoul Madariaga

Senior researcher

Ecole Normale Supérieure Paris

www.spice-rtn.orgMid-Term Review Meeting, February 13-14, Tutzing

Earthquake seismology

Fault model

Rupture propagation model

Wave propagation model

Kinematics

DynamicsModelling

Propagation

Direct Inverse

www.spice-rtn.orgMid-Term Review Meeting, February 13-14, Tutzing

.BB Seismic waves

Hifi Seismic waves

Different scales in earthquake dynamics

Macroscale

Mesoscale

MicroscaleSteady state mechanicsvr

(< 0.3 Hz 5 km)

(>0.5 Hz <2 km)

(non-radiative)

(~ 100 m) This hierarchy of problems was proposed by Kostrov’s

www.spice-rtn.orgMid-Term Review Meeting, February 13-14, Tutzing

Challenges in macroscale

Kinematics : Are inversions realistic? -> Don’t ask!Are they stable? -> Blind Test

Dynamics : How do we set up kinematic inversions that are compatible with dynamics ?

Both : How to extend the inversions beyond0.3 Hz, so that they are useful inengineering ?

How to interface with GPS, interferometry and geology?

www.spice-rtn.orgMid-Term Review Meeting, February 13-14, Tutzing

Earthquakes as dynamic shear ruptures

Preexisting Fault systemin the Mojave desert

Rupture modelled on the complex faultsystem determined from Geology, Geodesy andSeismology

Epicenter

www.spice-rtn.orgMid-Term Review Meeting, February 13-14, Tutzing

Kinematic vs dynamic modelling

PeyratOlsenMadariaga2001

Wald andHeaton1994

Landers

28 June 1992

www.spice-rtn.orgMid-Term Review Meeting, February 13-14, Tutzing

Model B Model EThe « smooth » fault modeldevelops supershear shocks

The « rough » fault models produces

subshear ruptures

Why? Detailed energy balance

Two attempts to model the Izmit Earthquake

Super shear shock Aochi, Fuyama, Madariaga, 2003

www.spice-rtn.orgMid-Term Review Meeting, February 13-14, Tutzing

vr

A simple shear crack (earthquake) moving at fast speed

Local energy balance

Gc U

Dc

slip

friction

ini

Es = U - Gc

www.spice-rtn.orgMid-Term Review Meeting, February 13-14, Tutzing

Mesoscale: Compare a complex fault to a flat one

Velocity z Stresszy Stress zx

Rupture front

Residual stressesS waves

Slow rupture

Madariaga and Ampuero, AGU 05

www.spice-rtn.orgMid-Term Review Meeting, February 13-14, Tutzing

Outlook for Next 2 years

Earthquake seismology progresses as earthquake recording

and data availability improves

Kinematics: Improvement of wave propagation, methodology and structure (Bonnefoy, Oprsal, Tapia)

Kinematics inversion: Compare linear and non- linear techniques. (Holden, Festa)

Dynamic inversion: Do it! Let it become the norm rather than the exception. (DiCarli, Burjanek)

Mesocale : Understand the generation of high frequencies and EQ energy balance

Microscale: See Pablo Ampuero’s presentation