Earth-prints repository, logo   DSpace

About DSpace Software
|earth-prints home page | roma library | bologna library | catania library | milano library | napoli library | palermo library
Please use this identifier to cite or link to this item:

Authors: Bizzarri, A.*
Spudich, P.*
Title: Effects of supershear rupture speed on the high-frequency content of S waves investigated using spontaneous dynamic rupture models and isochrone theory
Title of journal: Journal of Geophysical Research
Series/Report no.: /113 (2008)
Publisher: AGU
Issue Date: 7-May-2008
DOI: 10.1029/2007JB005146
Keywords: supershear ruptures
Abstract: In this paper we achieve three goals: (1) We demonstrate that crack tips governed by friction laws, including slip weakening, rate- and state-dependent laws, and thermal pressurization of pore fluids, propagating at supershear speed have slip velocity functions with reduced high-frequency content compared to crack tips traveling at subshear speeds. This is demonstrated using a fully dynamic, spontaneous, three-dimensional earthquake model, in which we calculate fault slip velocity at nine points (locations) distributed along a quarter circle on the fault where the rupture is traveling at supershear speed in the inplane direction and subshear speed in the antiplane direction. This holds for a fault governed by the linear slip-weakening constitutive equation, by slip weakening with thermal pressurization of pore fluid, and by rate- and state-dependent laws with thermal pressurization. The same is also true even assuming a highly heterogeneous initial shear stress field on the fault. (2) Using isochrone theory, we derive a general expression for the spectral characteristics and geometric spreading of two pulses arising from supershear rupture, the well-known Mach wave, and a second lesser known pulse caused by rupture acceleration. (3) We demonstrate that the Mach cone amplification of high frequencies overwhelms the de-amplification of high-frequency content in the slip velocity functions in supershear ruptures. Consequently, when earthquake ruptures travel at supershear speed, a net enhancement of high-frequency radiation is expected, and the alleged ‘‘low’’ peak accelerations observed for the 2002 Denali and other large earthquakes are probably not caused by diminished high-frequency content in the slip velocity function, as has been speculated.
Appears in Collections:04.06.09. Waves and wave analysis
Papers Published / Papers in press

Files in This Item:

File SizeFormatVisibility
2007JB005146.pdf1.41 MBAdobe PDFView/Open

This item is licensed under a Creative Commons License
Creative Commons

Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.

Share this record




Stumble it!



Valid XHTML 1.0! ICT Support, development & maintenance are provided by CINECA. Powered on DSpace Software. CINECA