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Moho depth variation in southern California from teleseismic receiver functions

Zhu, Lupei and Kanamori, Hiroo (2000) Moho depth variation in southern California from teleseismic receiver functions. Journal of Geophysical Research B, 105 (B2). pp. 2969-2980. ISSN 0148-0227. doi:10.1029/1999JB900322.

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The number of broadband three-component seismic stations in southern California has more than tripled recently. In this study we use the teleseismic receiver function technique to determine the crustal thicknesses and V_p/V_s ratios for these stations and map out the lateral variation of Moho depth under southern California. It is shown that a receiver function can provide a very good “point” measurement of crustal thickness under a broadband station and is not sensitive to crustal P velocity. However, the crustal thickness estimated only from the delay time of the Moho P-to-S converted phase trades off strongly with the crustal V_p/V_s ratio. The ambiguity can be reduced significantly by incorporating the later multiple converted phases, namely, the PpPs and PpSs+PsPs. We propose a stacking algorithm which sums the amplitudes of receiver function at the predicted arrival times of these phases by different crustal thicknesses H and Vp/Vs ratios. This transforms the time domain receiver functions directly into the H-V_p/V_s domain without need to identify these phases and to pick their arrival times. The best estimations of crustal thickness and V_p/V_s ratio are found when the three phases are stacked coherently. By stacking receiver functions from different distances and directions, effects of lateral structural variation are suppressed, and an average crustal model is obtained. Applying this technique to 84 digital broadband stations in southern California reveals that the Moho depth is 29 km on average and varies from 21 to 37 km. Deeper Mohos are found under the eastern Transverse Range, the Peninsular Range, and the Sierra Nevada Range. The central Transverse Range, however, does not have a crustal root. Thin crusts exist in the Inner California Borderland (21–22 km) and the Salton Trough (22 km). The Moho is relatively flat at the average depth in the western and central Mojave Desert and becomes shallower to the east under the Eastern California Shear Zone (ECSZ). Southern California crust has an average V_p/V_s ratio of 1.78, with higher ratios of 1.8 to 1.85 in the mountain ranges with Mesozoic basement and lower ratios in the Mojave Block except for the ECSZ, where the ratio increases.

Item Type:Article
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Kanamori, Hiroo0000-0001-8219-9428
Additional Information:© 2000 American Geophysical Union. Received March 23, 1999; revised September 6, 1999: accepted September 14, 1999. Article first published online: 20 Sep 2012. Paper number 1999JB900322. We are grateful to the staff at the SCEC data center and IRIS DMC, who helped retrieving the waveform data. Chuck Ammon provided the tele-seismic waveform of LAC. Comments from G. Zandt, C. Thurber, and an anonymous reviewer have greatly improve the manuscript. This research was supported by the Southern California Earthquake Center. SCEC is funded by NSF Cooperative Agreement EAR-8920136 and USGS Cooperative Agreements 14-08-0001-A0899 and 1434-HQ-97AG01718. This is SCEC contribution 464 and Division of Geological and Planetary Sciences, Caltech, contribution 8621.
Group:UNSPECIFIED, Division of Geological and Planetary Sciences
Funding AgencyGrant Number
Southern California Earthquake Center (SCEC)UNSPECIFIED
NSF Cooperative AgreementEAR-8920136
USGS Cooperative Agreement14-08-0001-A0899
USGS Cooperative Agreement1434-HQ-97AG01718
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Other Numbering System NameOther Numbering System ID
Southern California Earthquake Center (SCEC)464
Caltech Division of Geological and Planetary Sciences8621
Issue or Number:B2
Record Number:CaltechAUTHORS:20141112-103948033
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Official Citation:Zhu, L., and H. Kanamori (2000), Moho depth variation in southern California from teleseismic receiver functions, J. Geophys. Res., 105(B2), 2969–2980, doi:10.1029/1999JB900322.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:51645
Deposited By: Ruth Sustaita
Deposited On:12 Nov 2014 20:54
Last Modified:12 Oct 2022 16:19

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