. Bulletin. Science; Natural history; Natural history. MASS MOVEMENT ALONG SOUTHERN CALIFORNIA COAST 69. Fig. 7. The Point Fermin Landslide in February 1941, showing the relationship between mass movement and marine erosion. Reactivation in 1940-41 occurred within the framework of the larger 1929 landslide whose subdued headscarp is visible between buildings towards the top right (Spence Collection, UCLA, February 1941). for more than 1500 m along the crest of the hills may also have formed from landslide activity, perhaps aided by tectonic extension (Merriam 1960; Ehlert 1986). Three areas of
. Bulletin. Science; Natural history; Natural history. MASS MOVEMENT ALONG SOUTHERN CALIFORNIA COAST 69. Fig. 7. The Point Fermin Landslide in February 1941, showing the relationship between mass movement and marine erosion. Reactivation in 1940-41 occurred within the framework of the larger 1929 landslide whose subdued headscarp is visible between buildings towards the top right (Spence Collection, UCLA, February 1941). for more than 1500 m along the crest of the hills may also have formed from landslide activity, perhaps aided by tectonic extension (Merriam 1960; Ehlert 1986). Three areas of reactivation are commonly recognized, namely the Klondike Canyon, Portuguese Bend, and Abalone Cove landslides. Renewed movement of the Klondike Canyon Landslide was recognized in 1979. The mass is underlain by several seaward-dipping tuff beds, including the 15 m thick Portuguese Tuff, and reaches the coast in eroding seacliffs up to 50 m high (Kerwin 1982). The 110 ha Portuguese Bend Landslide began renewed movement in August 1956, again in association with seaward-dipping tuffs and low-angle slide planes, some of the latter overlying inactive landslide material. Los Angeles County was later found legally responsible for this reactivation, having loaded the headscarp area with roadfill during the extension of Crenshaw Boulevard (Ehlig 1982). In- creased groundwater levels associated with home construction and water-line breakage may have aggravated the problem. Certainly, water has since come to be regarded as the primary trigger of continuing activity. Initial movement was a dramatic 7-10 cm/day and, although this later slowed, cumulative lateral dis- placement of 80-240+ m has occurred since 1956. Towards the coast, the slide mass thrusts upwards at a steep angle against the 30 m thick basalt sill that buttresses Portuguese Point and Inspiration Point. In the broad cove to the east, reinforced concrete caissons were emplaced in 1957 to stop movement but these. Please note
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