Earthquakes, faulting, and stress in the Los Angeles Basin

摘要: Since 1920 fourteen moderate-sized (M_L = 4.9–6.4) earthquakes have been reported in the Los Angeles basin. These events are associated with both mappable surficial faults and concealed beneath basin sediments. To determine style of faulting state stress basin, single-event focal mechanisms for 244 M ≥ 2.5 that occurred during 1977–1989 calculated. Fifty-nine percent strike-slip mostly located near two major, northwest striking right-lateral Newport-Inglewood fault Palos Verdes fault. The 1988 Pasadena Upland showed left-lateral on northeast faults. Numerous small eastern part show form a trend Yorba Linda. Thirty-two reverse distributed along broad zones. first, Elysian Park fold thrust belt, coincides anticlines northern flank extending into Santa Monica Bay. second, Torrance-Wilmington mapped southwest extends from offshore Newport Beach to Oblique could be inferred by merging compressional tectonics does not occur Instead, coexistence zones thrusting large suggests movements decoupled. A few normal appear related orthogonal axes plunging anticlines. maximum horizontal varies N1°W N31°E across consistently forms high angles axes. field exists flanks has vertical minimum axis. This ongoing folding suggest tectonic deformation is concentrated deep central Today consists uplift crustal thickening lateral block movement accommodate north-south compression