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Detailed Reference Information |
Clarke, T.J., Silver, P.G., Yeh, Y., James, D.E., Wallace, T.C. and Beck, S.L. (1995). Close in ScS and sScS reverberations from the 9 June 1994 Bolivian Earthquake. Geophysical Research Letters 22: doi: 10.1029/95GL02062. issn: 0094-8276. |
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Recordings of the Bolivian Earthquake of 9 June, 1994 from two portable experiments were analyzed for ScS and sScS reverberations. These stations span the distance range 6¿--22¿, sampling the mantle beneath South America along an EW line from the central Andes to the Brazilian Craton. We used the CORE method to obtain path-averaged locations of the Moho and 400 and 660 km discontinuities. The average depth for D400 is 410 km for the BANJO stations and 395 km beneath Brazil, and the value for D660 is 700 km for BANJO and 675 km for BLSP, while the difference D660-D400≡ΔD is 290 km and 280 km, respectively. These values are much larger than the global average (around 245 km) and suggest 200¿--300¿ colder temperatures in the region sampled. This is most plausibly explained by the reduced temperatures in the slab and surrounding region. We also detect a significant discontinuity at 210 km depth, with a shear wave impedance increase of at least 5%. Finally, we observe systematic variations in duration between P, ScS, and sScS that can only be attributed to source finiteness. These observations constrain the inclination of an equivalent unilateral rupture velocity vector to be -17¿ (positive up from horizontal). Our rupture model is consistent with modes derived from subevent analysis of the P wave arrivals, and implies a source extent of 72 km. ¿ American Geophysical Union 1995 |
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Abstract |
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Keywords
Seismology, Seismicity and seismotectonics, Tectonophysics, Dynamics of lithosphere and mantle—general |
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Publisher
American Geophysical Union 2000 Florida Avenue N.W. Washington, D.C. 20009-1277 USA 1-202-462-6900 1-202-328-0566 service@agu.org |
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