Multistation infrasonic observations of the Chilean earthquake of 2005 June 13

SUMMARY On 2005 June 13, a major earthquake (M7.8) occurred in the Tarapaca region (North Chile), within the region of high mountains. At large distances from the epicentre, this event produced coherent infrasonic waves detected by three infrasound stations that are part of the International Monitoring System. The observed azimuth variations and the long signal durations suggest that wide regions in the Andes Mountains radiated infrasonic waves. From these observations, the main sources' regions are reconstructed. Such an event recorded by multiple stations offers an unique opportunity to evaluate the relative contributions of the different source mechanisms involved in large earthquakes as well as to improve our understanding of the amplification of ground displacement caused by the topography. With a review of infrasound signals from past earthquakes, extended empirical scaling relations are derived. We show that beyond the seismic magnitude, both seismic source and topographic features also play a predominant role in the generation of infrasound.

[1]  A. Gault,et al.  Infrasonic Signal Detection and Source Location at the Prototype International Data Centre , 2002 .

[2]  Rodney W. Whitaker,et al.  Infrasound from earthquakes , 2005 .

[3]  M. Vallée,et al.  Infrasonic imaging of the Kunlun Mountains for the great 2001 China earthquake , 2003 .

[4]  Giuliano F. Panza,et al.  Theoretical and Observed Depth Correction for Ms , 2001 .

[5]  T. Mikumo.  Atmospheric pressure waves and tectonic deformation associated with the Alaskan earthquake of March 28, 1964 , 1968 .

[6]  M. Bouchon.  A simple method to calculate Green's functions for elastic layered media , 1981 .

[7]  J. Virieux,et al.  Infrasound modeling in a spherical heterogeneous atmosphere , 2005 .

[8]  M. Vallée,et al.  Imaging coseismic rupture in far field by slip patches , 2004 .

[9]  Lars Ceranna,et al.  Infrasound associated with 2004–2005 large Sumatra earthquakes and tsunami , 2005 .

[10]  Brian W. Stump,et al.  Local infrasound signals from the Tokachi‐Oki earthquake , 2004 .

[11]  Nicolas Brachet,et al.  Ground‐coupled air waves and diffracted infrasound from the Arequipa earthquake of June 23, 2001 , 2001 .

[12]  Roger Hansen,et al.  Infrasound associated with the 2002 Denali fault earthquake, Alaska , 2003 .

[13]  E. Posmentier,et al.  Ground‐coupled air waves from the Great Alaskan Earthquake , 1964 .

[14]  H. Bass,et al.  Deep infrasound radiated by the Sumatra earthquake and tsunami , 2005 .

[15]  Christian Madshus,et al.  Air-ground interaction in long range propagation of low frequency sound and vibration - field tests and model verification , 2005 .

[16]  J. Virieux,et al.  Paraxial ray tracing for atmospheric wave propagation , 2004 .

[17]  Charles R. Wilson,et al.  Listening to the secret sounds of Earth's atmosphere , 2002 .

[18]  Yves Cansi,et al.  An automatic seismic event processing for detection and location: The P.M.C.C. Method , 1995 .

[19]  J. M. Young,et al.  Anomalous infrasound generated by the Alaskan earthquake of 28 March 1964 , 1982 .

[20]  Milton Garces,et al.  Traveltimes for infrasonic waves propagating in a stratified atmosphere , 1998 .

[21]  Milton Garces,et al.  Global morphology of infrasound propagation , 2003 .

[22]  Henry E. Bass,et al.  Atmospheric absorption in the atmosphere up to 160 km , 2004 .