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| La Jolla Slide | |
|---|---|
| Name | La Jolla Slide |
| Type | submarine landslide |
| Location | La Jolla, San Diego County, California |
| Epoch | Holocene |
La Jolla Slide is a large submerged mass-wasting feature off the coast of La Jolla in San Diego County, California, representing one of the more studied submarine slides on the continental margin of the Pacific Ocean. The feature has been investigated by researchers from institutions including Scripps Institution of Oceanography, United States Geological Survey, and Naval Research Laboratory using seismic profiling, coring, and bathymetric mapping. Its geomorphic expression, stratigraphic record, and inferred tsunami potential have linked it to wider discussions of slope failure along the California Continental Borderlands, Eastern Pacific margins, and other notable slides such as the Hueneme Slide and Monterey Canyon failures.
The slide occupies parts of the nearshore continental shelf and upper slope adjacent to La Jolla and shows classic geomorphic elements including a headscarp, translational blocky terrain, and a distal lobate deposit. High-resolution multibeam bathymetry and subbottom seismic profiles reveal scarps incised into Pleistocene and Holocene strata and a hummocky terrain comparable to features documented at Storegga Slide and Nankai Trough margin examples. Lithologies involved include Quaternary shelf sands, late Pleistocene terrestrial deposits, and locally derived Tertiary shelf sediments. Morphodynamic processes governing its morphology include oversteepening, pore-pressure alteration, and sediment remobilization analogous to mechanisms observed at the Gulf of Mexico slope and Cascadia margin failures.
The slide lies offshore of La Jolla and extends along the inner continental shelf-slope break southwest of Point La Jolla toward the Scripps Canyon area. Bathymetric surveys place its headscarp within tens to a few hundred meters of the modern shoreline, with runout extending onto the upper slope and into adjacent basins near La Jolla Canyon and the outer shelf. Spatially it is juxtaposed to anthropogenic landmarks including coastal installations in San Diego and proximal to natural features like La Jolla Shores and Torrey Pines State Reserve. The lateral extent and areal footprint have been constrained by studies employing multibeam echo sounder mosaics and seismic-reflection transects collected by research vessels associated with Scripps Institution of Oceanography and NOAA.
The slide occurs within the complex transform- and convergent-influenced tectonic mosaic of southern California. Regional plate interactions involve the Pacific Plate and the North American Plate and are modulated by local structures including the Rose Canyon Fault and other coastal fault systems. Seismotectonic activity, including earthquakes on the Rose Canyon Fault, San Andreas Fault system stress transfer, and regional uplift and subsidence, contributes to slope destabilization. Additional triggers include rapid sedimentation sourced from ancient river systems and cliff erosion at Torrey Pines and La Jolla bluffs, elevated pore pressures in fine-grained intervals, and ground-shaking comparable to historic events such as the 1857 Fort Tejon earthquake and later 1933 Long Beach earthquake—all analogous forcings documented at other submarine slide sites.
Stratigraphic correlation and radiocarbon-dated cores indicate episodes of failure spanning the Late Pleistocene into the Holocene, with some studies identifying discrete, possibly multiple collapse events. Sediment cores recovered by teams from Scripps Institution of Oceanography and USGS show mixed ages within chaotic deposits, consistent with rapid emplacement during single or successive failures. Chronologies inferred from foraminiferal assemblages and radiocarbon dating align some major events with episodes of sea-level rise following the Last Glacial Maximum and with regional seismic episodes recorded in the paleoseismic record along southern California coasts.
Deposits attributed to the slide comprise a heterogeneous assemblage of blocky, matrix-supported debris, turbidite-like lobes, and reworked shelf sediments containing shallow marine fossils and terrestrial organic matter. Grain-size distributions and sedimentary structures preserved in cores display graded beds, chaotic acoustic facies, and slump folding analogous to deposits documented at Hawaii and Canary Islands submarine failures. Geochemical signatures, including organic carbon content and microfossil assemblages, have been used by Scripps Institution of Oceanography researchers to differentiate slide-derived deposits from background hemipelagic sedimentation and to reconstruct emplacement dynamics.
Given its proximity to populated areas of San Diego and recreational beaches like La Jolla Shores, the slide has been evaluated for its tsunami-generating potential. Modeling studies referenced by NOAA and academic groups suggest that large rapid failures could generate locally significant coastal waves, comparable in hazard scope to tsunamis modeled for the Hueneme Slide and other southern California mass-wasting events. Hazard assessments integrate slide volume estimates, runout dynamics, and coupling efficiency to the water column, and they are considered alongside seismic scenarios for the Rose Canyon Fault and regional rupture models used by emergency planners in San Diego County.
Investigation has combined multibeam bathymetry, side-scan sonar, high-resolution seismic-reflection profiling, piston and gravity coring, sedimentological analysis, and numerical tsunami and slope-stability modeling. Collaborative programs involving Scripps Institution of Oceanography, USGS, NOAA, and university research vessels deploy autonomous underwater vehicles and remotely operated vehicles for visual inspection. Continuous efforts tie marine geophysical data to onshore paleoseismic records from San Diego area trenching studies and to seismic networks operated by Caltech and USGS for improved real-time monitoring and probabilistic hazard estimation.
Category:Submarine landslides