Ring-Shaped Seismicity Structures in Southern California: Possible Preparation for Large Earthquake in the Los Angeles Basin
- 21 Downloads
Some characteristics of seismicity in Southern California are studied. It is found that ring-shaped seismicity structures with threshold magnitudes Mth of 4.1, 4.1, and 3.8 formed prior to three large (M w > 7.0) earthquakes in 1992, 1999, and 2010, respectively. The sizes of these structures are several times smaller than for intracontinental strike-slip events with similar magnitudes. Two ring-shaped structures are identified in areas east of the city of Los Angeles, where relatively large earthquakes have not occurred for at least 150 years. The magnitudes of large events which can occur in the areas of these structures are estimated on the basis of the previously obtained correlation dependence of ring sizes on magnitudes of the strike-slip earthquakes. Large events with magnitudes of M w = 6.9 ± 0.2 and M w = 8.6 ± 0.2 can occur in the area to the east of the city of Los Angeles and in the rupture zone of the 1857 great Fort Tejon earthquake, respectively. We believe that ring-structure formation, similarly to the other regions, is connected with deep-seated fluid migration.
KeywordsEarth’s crust ring-shaped seismicity structures large earthquakes deep-seated fluids
Unable to display preview. Download preview PDF.
- Glubinnoe stroenie slaboseismichnykh regionov SSSR (The Deep Structure of Weakly Seismic Regions of the USSR), Shchukin, Yu.K. and Ryaba, V.Z, Eds., Moscow: Nauka, 1987.Google Scholar
- Kopnichev, Yu.F. and Sokolova, I.N., Inhomogeneities in the field of absorption of short-period S-waves near the source of the Maule earthquake (Chile, February 27, 2010, M w = 8.8) and their relation to seismicity and volcanism, Geofiz. Issled., 2011b, vol. 12, no. 3, pp. 22–33.Google Scholar
- Kopnichev, Yu.F. and Sokolova, I.N., Inhomogeneities in the field of S-wave absorption and ring structures of seismicity in the area of the Baikal Rift Zone, Vestn. Nats. Yad. Tsentra Resp. Kaz., 2012, no. 4, pp. 33–41.Google Scholar
- Kopnichev, Yu.F. and Sokolova, I.N., Ring structures of seismicity generated in the continental areas before strong earthquakes with different source mechanisms, Geofiz. Issled., 2013a, vol. 14, no. 1, pp. 5–15.Google Scholar
- Kopnichev, Yu.F. and Sokolova, I.N., Ring structures of seismicity generated before strong earthquakes in the northwestern and eastern Pacific, Vestn. Nats. Yad. Tsentra Resp. Kaz., 2013b, no. 2, pp. 131–140.Google Scholar
- Kopnichev, Yu.F. and Sokolova, I.N., Ring structures of seismicity in northern Chile and a successful forecast of the place and magnitude of the Iquique earthquake on April 1, 2014 (M w = 8.2), Vestn. Nats. Yad. Tsentra Resp. Kaz., 2015, no. 4, pp. 153–159.Google Scholar
- Letnikov, F.A., Sinergetika geologicheskikh sistem (Synergetics of Geological Processes), Novosibirsk: Nauka, 1992.Google Scholar
- Rodkin, M.V., Rol’ glubinnogo flyuidnogo rezhima v geodinamike i seismotektonike (The Role of the Deep Fluid Regime in Geodynamics and Seismotectonics), Moscow, 1993.Google Scholar
- Sieh K. Slip along the San Andreas fault associated with the great 1857 earthquake // Bull. Seismol. Soc. Amer. 1978. V. 68, N 5. P. 1421–1448.Google Scholar