NEHRP Clearinghouse
- Title
- Implications for the Formation of the Hollywood Basin from Gravity Interpretations of the Northern Los Angeles Basin, California.
- File
- PB2006105465.pdf
- Author(s)
- Hildenbrand, T. G.; Davidson, J. G.; Ponti, D. J.; Langenheim, V. E.
- Source
- January 2001, 32 p.
- Identifying Number(s)
- USGS/OFR-2001-394
- Abstract
- Gravity data provide insights on the complex tectonic history and structural development of the northern Los Angeles Basin region. The Hollywood basin appears to be a long (> 12 km), narrow (up to 2 km wide) trough lying between the Santa Monica Mountains and the Wilshire arch. In the deepest parts of the Hollywood basin, the modeled average thickness ranges from roughly 250 m if filled with only Quaternary sediments to approximately 600 m if Pliocene sediments are also present. Interpretations of conflicting drill hole data force us to consider both these scenarios. Because of the marked density contrast between the dense Santa Monica Mountains and the low-density sediments in the Los Angeles Basin, the gravity method is particularly useful in mapping the maximum displacement along the Santa Monica-Hollywood-Raymond fault zone. The gravity-defined Santa Monica-Hollywood fault zone deviates, in places, from the mapped active fault and fold scarps located with boreholes and trenching and by geomorphologic mapping by Dolan and others (1997).
- Keywords
- Density boundaries; Northern Los Angeles Basin; Geology; California; Shallow sources; Gravity data; Geologic history; Gravity surveys; Inversion models; Seismic surveys; Interpretive techniques; Gravitational effects; Holloywood Basin; Earthquakes