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Sensitivity densities for rotational ground-motion measurements

Andreas Fichtner and Heiner Igel
Sensitivity densities for rotational ground-motion measurements (in Rotational seismology and engineering applications, William H. K. Lee (editor), M. Celebi (editor), M. I. Todorovska (editor) and Heiner Igel (editor))
Bulletin of the Seismological Society of America (May 2009) 99 (2B): 1302-1314

Abstract

We derive and analyze sensitivity densities for two quantities derived from rotational ground-motion measurements: the rms (root-mean-square) amplitude A (sub omega ) of the rotation seismogram omega =1/2Xu and the apparent shear-wave speed beta (super a) =1/2 A (sub upsilon ) /A (sub omega ) , where A (sub v) denotes the rms amplitude of the velocity seismogram. In the case of a plane S wave in a homogeneous and isotropic medium, beta (sub a) coincides with the true shear-wave speed beta . Based on analytical and numerical examples, we demonstrate that the beta (sub a) kernels attain large absolute values only in the vicinity of the receiver but not in the vicinity of the source. This effect is pronounced in the case of both body S waves and surface waves (Love+Rayleigh). Moreover, the beta (sub a) kernels are dominated by the higher Fresnel zones while reaching only small absolute values in the first Fresnel zone. This implies (1) that measurements of beta (sub a) are to the first order independent of the Earth structure near the source, (2) that such measurements may be used for one-station local shear-wave speed tomography, and (3) that comparatively low-frequency signals can be used in order to invert for small-scale structures. The sensitivity densities corresponding to the rotation amplitude measurement A (sub omega ) resemble those for the velocity amplitude measurements A (sub v) . It is, therefore, the combination of A (sub omega ) with A (sub v) , and not one of them alone, that is likely to provide additional constraints on the Earth's structure near the receiver.


ISSN: 0037-1106
EISSN: 1943-3573
Coden: BSSAAP
Serial Title: Bulletin of the Seismological Society of America
Serial Volume: 99
Serial Issue: 2B
Title: Sensitivity densities for rotational ground-motion measurements
Title: Rotational seismology and engineering applications
Author(s): Fichtner, AndreasIgel, Heiner
Author(s): Lee, William H. K.editor
Author(s): Celebi, M.editor
Author(s): Todorovska, M. I.editor
Author(s): Igel, Heinereditor
Affiliation: Ludwig Maximilian University, Department of Earth and Environmental Sciences, Munich, Federal Republic of Germany
Affiliation: U. S. Geological Survey, Palo Alto, CA, United States
Pages: 1302-1314
Published: 200905
Text Language: English
Publisher: Seismological Society of America, Berkeley, CA, United States
Meeting name: First international workshop on Rotational seismology and engineering applications
Meeting location: Menlo Park, CA, USA, United States
Meeting date: 20070918Sept. 18-19, 2007
References: 24
Accession Number: 2009-050057
Categories: Seismology
Document Type: Serial Conference document
Bibliographic Level: Analytic
Illustration Description: illus.
Secondary Affiliation: University of Southern California, USA, United StatesLudwig Maximilians Universitaet Muenchen, DEU, Federal Republic of Germany
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Abstract, Copyright, Seismological Society of America. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 200927
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