Attenuation of seismic shear wave energy in Switzerland

SUMMARY Modelling the attenuation of shear wave energy is an important component of seismic hazard analysis. Previous studies have shown how attenuation, particularly in the uppermost layers of the crust, is regionally dependent. The impact of this is that the decay of energy radiating from an earthquake will vary from place to place. To quantify the regional attenuation in Switzerland we model the Fourier spectral amplitude of small-to-moderate earthquakes, recorded on the local seismic networks. High-frequency decay is parametrized by Q and κ, while apparent geometrical spreading models account for the frequency-independent decay of energy. We analyse ground motion encompassing the significant duration of shaking to provide models that are useful for the purpose of seismic hazard analysis. Two methods are used to estimate the whole path attenuation parameter, t*: first, a simultaneous fit of the source model and attenuation effects across the entire spectral bandwidth for earthquakes with M > 2; and secondly, a linear fit of an attenuation model to the high-frequency part of the spectrum for earthquakes with M > 3.5. The t* parameter is found to vary with hypocentral distance consistent with a weakly attenuating crust and strongly attenuating uppermost layer. 1-D tomographic inversions indicate a profile of increasing Q with depth down to the Moho. Frequency-independent decay is parametrized using a three-part model which allows for the inclusion of Moho reflection phases in the spectrum in the range of 20–140 km in the Swiss Foreland and from 70 to 140 km in the Swiss Alps.

[1]  D. Fäh,et al.  Derivation of a Reference Shear-Wave Velocity Model from Empirical Site Amplification , 2011 .

[2]  Benjamin Edwards,et al.  Earthquakes in Switzerland and surrounding regions during 2009 , 2010 .

[3]  Benjamin Edwards,et al.  Automatic computation of moment magnitudes for small earthquakes and the scaling of local to moment magnitude , 2010 .

[4]  Won-Young Kim,et al.  The 2002 M5 Au Sable Forks, NY, earthquake sequence: Source scaling relationships and energy budget , 2010 .

[5]  G. McVerry,et al.  Influence of the 3D Distribution of Q and Crustal Structure on Ground Motions from the 2003 Mw 7.2 Fiordland, New Zealand, Earthquake , 2010 .

[6]  Stéphane Drouet,et al.  vS30, κ, regional attenuation and Mw from accelerograms: application to magnitude 3–5 French earthquakes , 2010 .

[7]  John Douglas,et al.  A κ Model for Mainland France , 2010 .

[8]  Luca Malagnini,et al.  Source radiation invariant property of local and near‐regional shear‐wave coda: Application to source scaling for the Mw 5.9 Wells, Nevada sequence , 2010 .

[9]  Donat Fäh,et al.  Estimating Rayleigh wave particle motion from three-component array analysis of ambient vibrations , 2010 .

[10]  Benjamin Edwards,et al.  A Comparative Study on Attenuation and Source-Scaling Relations in the Kanto, Tokai, and Chubu Regions of Japan, Using Data from Hi-Net and KiK-Net , 2009 .

[11]  E. Morozova,et al.  Frequency Dependence of Coda Q, Part I: Numerical Modeling and Examples from Peaceful Nuclear Explosions , 2008 .

[12]  Julian J. Bommer,et al.  The Acquisition of Source, Path, and Site Effects from Microearthquake Recordings Using Q Tomography: Application to the United Kingdom , 2008 .

[13]  D. Eberhart‐Phillips,et al.  Three-dimensional attenuation structure of central and southern South Island, New Zealand, from local earthquakes , 2008 .

[14]  Donat Fäh,et al.  Analysis of three-component ambient vibration array measurements , 2008 .

[15]  Earth heterogeneity and scattering effects on seismic waves , 2008 .

[16]  Donat Fäh,et al.  S‐wave velocity measurements applied to the seismic microzonation of Basel, Upper Rhine Graben , 2007 .

[17]  Gail M. Atkinson,et al.  Earthquake Ground-Motion Prediction Equations for Eastern , 2007 .

[18]  Gail M. Atkinson,et al.  Earthquake Ground-Motion Prediction Equations for Eastern North America , 2006 .

[19]  N. Lam,et al.  Near-surface attenuation modelling based on rock shear-wave velocity profile , 2006 .

[20]  Luca Malagnini,et al.  Ground-Motion Scaling in the Western Alps , 2006 .

[21]  Julian J. Bommer,et al.  Criteria for Selecting and Adjusting Ground-Motion Models for Specific Target Regions: Application to Central Europe and Rock Sites , 2006 .

[22]  Frank Scherbaum,et al.  The Estimation of Minimum-Misfit Stochastic Models from Empirical Ground-Motion Prediction Equations , 2006 .

[23]  D. Giardini,et al.  Predictive ground motion scaling in Switzerland: Best estimates and uncertainties , 2005 .

[24]  W. Ellsworth,et al.  Apparent break in earthquake scaling due to path and site effects on deep borehole recordings , 2003 .

[25]  David M. Boore,et al.  Simulation of Ground Motion Using the Stochastic Method , 2003 .

[26]  D. Giardini,et al.  Spectral Shear-Wave Ground-Motion Scaling in Switzerland , 2003 .

[27]  Andreas Rietbrock,et al.  P wave attenuation structure in the fault area of the 1995 Kobe earthquake , 2001 .

[28]  R. Herrmann,et al.  Regional Ground-Motion Scaling in Central Europe , 2000 .

[29]  D. Giardini,et al.  Earthquakes in Switzerland and Surrounding Regions During 1999 , 2000 .

[30]  Luca Malagnini,et al.  Attenuation and excitation of three-component ground motion in southern California , 1999 .

[31]  Walter H. F. Smith,et al.  New, improved version of generic mapping tools released , 1998 .

[32]  G. R. Toro,et al.  Model of Strong Ground Motions from Earthquakes in Central and Eastern North America: Best Estimates and Uncertainties , 1997 .

[33]  J. Lees,et al.  Multiple-taper spectral analysis: a stand-alone C-subroutine , 1995 .

[34]  Gail M. Atkinson,et al.  The shape of ground motion attenuation curves in southeastern Canada , 1992, Bulletin of the Seismological Society of America.

[35]  David M. Boore,et al.  Fitting the stochastic ω−2 source model to observed response spectra in western north America: Trade-offs between Δσ and κ , 1992, Bulletin of the Seismological Society of America.

[36]  A. Frankel.  Mechanisms of seismic attenuation in the crust: Scattering and anelasticity in New York State, South Africa, and southern California , 1991 .

[37]  Frank Scherbaum,et al.  Combined inversion for the three-dimensional Q structure and source parameters using microearthquake spectra , 1990 .

[38]  Frank L. Vernon,et al.  Multitaper spectral analysis of high-frequency seismograms , 1987 .

[39]  William H. Press,et al.  Numerical recipes in C. The art of scientific computing , 1987 .

[40]  David M. Boore,et al.  Average body-wave radiation coefficients , 1984 .

[41]  John G. Anderson,et al.  A MODEL FOR THE SHAPE OF THE FOURIER AMPLITUDE SPECTRUM OF ACCELERATION AT HIGH FREQUENCIES , 1984 .

[42]  Clifford H. Thurber,et al.  Earthquake locations and three‐dimensional crustal structure in the Coyote Lake Area, central California , 1983 .

[43]  J. Brune.  Tectonic stress and the spectra of seismic shear waves from earthquakes , 1970 .

[44]  J. D. Eshelby.  The determination of the elastic field of an ellipsoidal inclusion, and related problems , 1957, Proceedings of the Royal Society of London. Series A. Mathematical and Physical Sciences.