Abstract Title: Closing the Gap between On and Offshore Records of Active 
Deformation in the Lake Tahoe Basin

Abstract Author(s): Seitz, Gordon, San Diego State University- Kent, Graham, 
Scripps Institution of Oceanography.- Karlin, Bob, University of Nevada Reno  

Abstract: Because Lake Tahoe is one of the oldest lakes in North America its 
sediments provide a unique and detailed record of long-term (3 Ma) basin 
evolution. We have begun to characterize the deformation across three active 
faults, within the Lake Tahoe basin, totaling 80 km in length, using a novel 
combination of swath bathymetry, high resolution seismic CHIRP, airborne laser 
altimetry imagery, AMS C-14 and OSL dated sediment cores. Multiple lines of 
submarine evidence support the conclusion that the Lake Tahoe Basin is 
tectonically active at a level characteristic of the most active Basin and 
Range faults. Currently the most robust extension rate estimate across the 
entire lake basin is 0.5 mm/yr ±0.35 mm/yr over 50 Ka. Most of the active Lake 
Tahoe faults are located in the deeper portions of the lake, however our 2004 
USGS funded research target, the Incline Village fault clearly extends onshore. 
Of the three major faults, the easternmost Incline Village fault creates a 
spectacular on and offshore scarp in late Pleistocene to early Holocene age 
deposits. This presents a unique opportunity to conduct an onshore trenching 
study in close proximity to a detailed offshore high-resolution seismic 3d grid 
with associated sediment coring. We anticipate that results from this study may 
provide the first onshore evidence of past earthquake occurrence for the Lake 
Tahoe Basin. Additionally, these results will provide a test for the 
Òearthquake induced turbidite modelÓ which promises paleoseismic records 
spanning the entire Holocene or longer, and is being applied here and 
elsewhere.