CaltechAUTHORS
  A Caltech Library Service

Spurious velocity changes caused by temporal variations in ambient noise frequency content

Zhan, Zhongwen and Tsai, Victor C. and Clayton, Robert W. (2013) Spurious velocity changes caused by temporal variations in ambient noise frequency content. Geophysical Journal International, 194 (3). pp. 1574-1581. ISSN 0956-540X. http://resolver.caltech.edu/CaltechAUTHORS:20130919-113717281

[img]
Preview
PDF - Published Version
See Usage Policy.

4Mb

Use this Persistent URL to link to this item: http://resolver.caltech.edu/CaltechAUTHORS:20130919-113717281

Abstract

Ambient seismic noise cross-correlations are now being used to detect temporal variations of seismic velocity, which are typically on the order of 0.1 per cent. At this small level, temporal variations in the properties of noise sources can cause apparent velocity changes. For example, the spatial distribution and frequency content of ambient noise have seasonal variations due to the seasonal hemispherical shift of storms. Here, we show that if the stretching method is used to measure time-shifts, then the temporal variability of noise frequency content causes apparent velocity changes due to the changes in both amplitude and phase spectra caused by waveform stretching. With realistic seasonal variations of frequency content in the Los Angeles Basin, our numerical tests produce about 0.05 per cent apparent velocity change, comparable to what Meier et al. observed in the Los Angeles Basin. We find that the apparent velocity change from waveform stretching depends on time windows and station-pair distances, and hence it is important to test a range of these parameters to diagnose the stretching bias. Better understanding of spatiotemporal noise source properties is critical for more accurate and reliable passive monitoring.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1093/gji/ggt170DOIArticle
http://gji.oxfordjournals.org/content/194/3/1574PublisherArticle
ORCID:
AuthorORCID
Tsai, Victor C.0000-0003-1809-6672
Clayton, Robert W.0000-0003-3323-3508
Additional Information:© The Authors 2013. Published by Oxford University Press on behalf of The Royal Astronomical Society. Accepted 2013 April 23; Received 2013 April 22; In original form 2013 February 18. We thank Fan-Chi Lin and Dongzhou Zhang for helpful discussions. We thank the editorMichael Ritzwoller and two anonymous reviewers for their comments that improved the manuscript. The facilities of the Southern California Earthquake Data Center (SCEDC), and the Southern California Seismic Network (SCSN), were used for access to waveforms data required in this study. This work is partially supported by the NSF/EAR-0838247 and Southern California Earthquake Center (12064).
Group:Seismological Laboratory
Funders:
Funding AgencyGrant Number
NSFEAR-0838247
Southern California Earthquake Center (SCEC)12064
Subject Keywords:Time-series analysis; Interferometry; Surface waves and free oscillations; Coda waves
Record Number:CaltechAUTHORS:20130919-113717281
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20130919-113717281
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:41411
Collection:CaltechAUTHORS
Deposited By: Jason Perez
Deposited On:19 Sep 2013 20:59
Last Modified:23 Nov 2016 19:41

Repository Staff Only: item control page