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Mitigating artifacts in back-projection source imaging with implications for frequency-dependent properties of the Tohoku-Oki earthquake

Meng, Lingsen and Ampuero, Jean-Paul and Luo, Yingdi and Wu, Wenbo and Ni, Sidao (2013) Mitigating artifacts in back-projection source imaging with implications for frequency-dependent properties of the Tohoku-Oki earthquake. Earth Planets and Space, 64 (12). pp. 1101-1109. ISSN 1343-8832. http://resolver.caltech.edu/CaltechAUTHORS:20130308-073907285

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Abstract

Comparing teleseismic array back-projection source images of the 2011 Tohoku-Oki earthquake with results from static and kinematic finite source inversions has revealed little overlap between the regions of high- and low-frequency slip. Motivated by this interesting observation, back-projection studies extended to intermediate frequencies, down to about 0.1 Hz, have suggested that a progressive transition of rupture properties as a function of frequency is observable. Here, by adapting the concept of array response function to non-stationary signals, we demonstrate that the "swimming artifact", a systematic drift resulting from signal non-stationarity, induces significant bias on beamforming back-projection at low frequencies. We introduce a "reference window strategy" into the multitaper-MUSIC back-projection technique and significantly mitigate the "swimming artifact" at high frequencies (1 s to 4 s). At lower frequencies, this modification yields notable, but significantly smaller, artifacts than time-domain stacking. We perform extensive synthetic tests that include a 3D regional velocity model for Japan. We analyze the recordings of the Tohoku-Oki earthquake at the USArray and at the European array at periods from 1 s to 16 s. The migration of the source location as a function of period, regardless of the back-projection methods, has characteristics that are consistent with the expected effect of the "swimming artifact". In particular, the apparent up-dip migration as a function of frequency obtained with the USArray can be explained by the "swimming artifact". This indicates that the most substantial frequency-dependence of the Tohoku-Oki earthquake source occurs at periods longer than 16 s. Thus, low-frequency back-projection needs to be further tested and validated in order to contribute to the characterization of frequency-dependent rupture properties.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.5047/eps.2012.05.010DOIArticle
http://www.terrapub.co.jp/journals/EPS/abstract/6412/64121101.htmlPublisherArticle
https://earth-planets-space.springeropen.com/articles/10.5047/eps.2012.05.010PublisherArticle
ORCID:
AuthorORCID
Ampuero, Jean-Paul0000-0002-4827-7987
Luo, Yingdi0000-0002-1165-6107
Additional Information:© 2013 The Society of Geomagnetism and Earth, Planetary and Space Sciences (SGEPSS); The Seismological Society of Japan; The Volcanological Society of Japan; The Geodetic Society of Japan; The Japanese Society for Planetary Sciences; TERRAPUB. Received December 27, 2011; Revised May 4, 2012; Accepted May 17, 2012; Online published January 28, 2013. This research was supported by NSF grant EAR-1015704, by the Gordon and Betty Moore Foundation and by the Southern California Earthquake Center, which is funded by NSF Cooperative Agreement EAR-0106924 and USGS Cooperative Agreement 02HQAG0008. The EarthScope USArray and the European ORFEUS data center were used to access the data. This paper is Caltech Tectonics Observatory contribution #198 and Caltech Seismolab contribution #10075.
Group:Caltech Tectonics Observatory, Seismological Laboratory
Funders:
Funding AgencyGrant Number
NSFEAR-1015704
Gordon and Betty Moore FoundationUNSPECIFIED
Southern California Earthquake Center (SCEC)UNSPECIFIED
NSFEAR-0106924
USGS02HQAG0008
Subject Keywords:Back-projection; Tohoku-Oki earthquake; frequency-dependent rupture properties; MUSIC; swimming artifact
Other Numbering System:
Other Numbering System NameOther Numbering System ID
Caltech Tectonics Observatory198
Caltech Division of Geological and Planetary Sciences10075
Record Number:CaltechAUTHORS:20130308-073907285
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20130308-073907285
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:37398
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:15 Apr 2013 19:00
Last Modified:26 Oct 2017 19:02

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