SEISMIC STRUCTURE OF THE LITHOSPHERE FROM TELESEISMIC CONVERTED ARRIVALS OBSERVED AT SMALL ARRAYS IN THE SOUTHERN SIERRA-NEVADA AND VICINITY, CALIFORNIA

21 well-distributed teleseisms (30 degrees to 100 degrees distance) we re recorded by mixed broad-band (BB) and short-period (SP) seismic arr ays at Mineral King (MK) and Horseshoe Meadow (HM) in the southern Sie rra Nevada and at Darwin Plateau (DP) between the Inyo and Argus range s. These arrays permit identification and separation of direct P and S arrivals, reflections from topography, scattered energy, and arrivals from different back azimuths (multipath arrivals). P-to-S conversions can be identified from beamed BE or SP seismograms. Least squares tim e domain processing recovered single-event receiver functions from the se beamed seismograms. Converted phases attributable to the Moho are c lear and uncomplicated at DP; Ps-P times of 3.9-4.2 s correspond to cr ustal thicknesses of 31-33 km, assuming a mean P crustal velocity of 6 .2 km/s and a Poisson's ratio (v) of 0.255. Ps-P times at HM (eastern Sierra) are 3.9-4.6 s (32-37 km) excepting some unusual seismograms fr om events at back azimuths of 225 degrees-239 degrees. MK (western Sie rra) times for Ps-P show a strong E-W asymmetry: 3.9-4.1 s (31-33 km) from the east, and 4.8-5.3 s (39-42 km) from the west. The MK arrivals from the east are multiple and substantially weaker by comparison wit h HM and DP. These results confirm the absence of a thick crust under the southern High Sierra inferred from both a refraction experiment co incident with this experiment and some earlier studies. At DP the Moho event follows an intracrustal negative polarity event defining the to p of an S wave low-velocity zone. This feature dips west under the Sie rran crest at HM but is absent farther west at MK. This feature appear s to be a manifestation of extensional strain and thus indicates that the surficially undeformed Sierra overlies a tectonized lower crust. S ub-Moho energy is absent under the Basin and Range (DP) but is conspic uous under the High Sierra at positive arrivals similar to 7.3 s (MK) and similar to 9 s (HM) after the P. These arrivals might be from the base of a low-velocity, low-density upper mantle body supporting the S ierra.