HR: 08:45h
AN: G51D-04    [Abstracts]
TI: Neotectonics and Contemporary Strain Accumulation Across the Walker Lane and Northern Great Basin, USA
AU: * Wesnousky, S G
EM: stevew@seismo.unr.edu
AF: Center for Neotectonic Studies, University of Nevada, Reno MS 169, Reno, NV, NV 89557 United States
AB: Neotectonic and paleoseismic studies provide an initial basis for comparison of Late Pleistocene strain release to modern measures of geodetic strain accumulation across the northern Great Basin, a region of diffuse continental extension. Available observations across the Great Basin between the 40th and 41st parallels indicate that geodetic strain accumulation and late Pleistocene recurrence of large surface rupture paleoearthquakes are each elevated along the Basin margins as compared to the interior. The central Nevada seismic belt, a north-northeast trending alignment of historical surface rupture earthquakes that trends into the interior of the Basin, shows a greater recurrence rate of late Pleistocene surface ruptures and increased levels of strain accumulation as compared to the interior Basin to the north and east. The observations when taken together suggest the pattern of strain release observed historically across the Basin and within the central Nevada seismic belt have been operative over at least the late Pleistocene. Thus, while the historical alignment of surface ruptures that defines the central Nevada seismic belt remains a unique clustering of earthquakes in time and space, the likelihood of the cluster at its observed location appears greater than would be expected to the east or northward in the interior of the Basin. The Walker Lane is composed of a discontinuous set of right-slip faults that strike subparallel to the San Andreas and along the western border of the Basin. Contemporary strain accumulation across the Lane decreases by up to a factor of 2 from north to south. The decrease in strain rate reflects a widening of the contemporary deformation field to include normal faults of the western Great Basin at about the latitude of the Central Walker Lane. The pattern of deformation appears long-lived. The northern limits of strike-slip faults in the Central Walker Lane are abrupt, the broadening of the geodetic strain field correlates spatially to the `Black Rock - Carson Sink Zone of Extension' originally defined by Wallace (1984) and interpreted as an area of possibly more rapid extension than surrounding areas during late Tertiary time, and measures of cumulative slip across the Walker Lane show a similar decrease from north to south.
DE: 6924 Interferometry (1207, 1209, 1242)
DE: 8107 Continental neotectonics (8002)
DE: 8109 Continental tectonics: extensional (0905)
SC: Geodesy [G]
MN: Fall Meeting 2005