Fallen leaf lake tahoe1/30/2024 ![]() Based on extent and timing, we suggest that four of the slides were triggered by events on the WTDPF if correct, these coseismic slides extend the paleoseismic record for the WTDPF and provide new insights into the rupture patterns along strike, and possibly between faults. Compressed high intensity radar pulse (Chirp) data beneath the Lake Tahoe subbasins Fallen Leaf Lake, Cascade Lake, and Emerald Bay image several large slide deposits correlated temporally between the three subbasins, as well as with previously dated slides in Lake Tahoe ( Smith et al., 2013). ![]() Several lines of evidence argue for seismic triggering of slide deposits, but the most convincing is a record of synchronous deposits across broad areas and multiple basins. Historic earthquakes have been shown to trigger mass movements in lacustrine and marine environments ( Hampton et al., 1996 Lee et al., 2009) recent studies have used slide deposits observed in sediment cores and seismic reflection data to estimate earthquake recurrence intervals ( Goldfinger et al., 2007 Schnellmann et al., 2002 Strasser et al., 2006 Upton and Osterberg, 2007). Furthermore, rupture timing patterns between the three WTDPF segments, Incline Village fault, and Stateline–North Tahoe fault remain poorly understood. (2005) based on slip-rate models, but the paleoseismic record has not been extended past the MREs on the Fallen Leaf Lake and Rubicon segments. A recurrence interval for the WTDPF of ∼4.8 k.y. The MRE on the Rubicon segment was dated as ca. The most recent event (MRE) on the Fallen Leaf Lake segment was 4.57–4.85 k.y. The WTDPF is a major north-south–striking normal fault, extending >50 km along the western margin of the Lake Tahoe Basin, and is divided by geomorphic discontinuities into three main segments: the southern Fallen Leaf Lake segment, central Rubicon segment, and northern Dollar Point segment ( Fig. Recent work in Fallen Leaf Lake has helped identify the WTDPF as potentially the most hazardous fault in the Lake Tahoe Basin, with the potential to produce M >7.0 earthquakes ( Brothers et al., 2009). These faults, the Stateline–North Tahoe fault, Incline Village fault, and the West Tahoe–Dollar Point fault (WTDPF), exhibit down to the east normal displacement ( Dingler et al., 2009) ( Fig. Onshore and offshore research in the Lake Tahoe Basin (northern Sierra Nevada, western United States) has defined the geometry and slip rates of the major faults accommodating active extension across the basin ( Brothers et al., 2009 Dingler et al., 2009 Gardner et al., 2000 Karlin et al., 2005 Kent et al., 2005 Schweickert et al., 2004 Seitz et al., 2006, 2005). ![]() This improved mapping of the WTDPF reveals the fault geometry and architecture south of Lake Tahoe and improves the geohazard assessment of the region. The Cascade Lake data combined with onshore Lidar allow us to map the WTDPF continuously between Fallen Leaf Lake and Cascade Lake. In addition, Chirp data beneath Cascade Lake image strands of the WTDPF offsetting the lake floor as much as ∼7.5 m. for large earthquakes on the Fallen Leaf Lake segment of the WTDPF, and the time since the most recent event (∼4.5 k.y. If this correlation is correct, we postulate a recurrence interval of ∼3–4 k.y. The temporal correlation of slides between multiple basins suggests triggering by earthquakes on the WTDPF system. Slide deposits imaged beneath Fallen Leaf Lake appear to be synchronous with slides in Lake Tahoe, Emerald Bay, and Cascade Lake. Here we present results from high-resolution seismic Chirp (compressed high intensity radar pulse) surveys in Fallen Leaf Lake and Cascade Lake, multibeam bathymetry coverage of Fallen Leaf Lake, onshore Lidar (light detection and ranging) data for the southern Lake Tahoe Basin, and radiocarbon dates from piston cores in Fallen Leaf Lake and Emerald Bay. Fallen Leaf Lake, Cascade Lake, and Emerald Bay are three subbasins of the Lake Tahoe Basin, located south of Lake Tahoe, and provide an opportunity to image primary earthquake deformation along the WTDPF and associated landslide deposits. The West Tahoe–Dollar Point fault (WTDPF) extends along the western margin of the Lake Tahoe Basin (northern Sierra Nevada, western United States) and is characterized as its most hazardous fault.
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