Large Events, Seismic Gaps, and Stress Diffusion in Central Chile
The time and space distribution of rupture segments along south-central Chile suggest the high probability of of a large magnitude earthquake occurring in the proposed seismic gap (34.3°–37.2°S) located between the 1960 and 1985 rupture regions. Three lines of evidence support the occurrence of a magnitude 8+ event within the next couple of decades. First the repeat time of large magnitude earthquakes is 90±6 years; the last such shock was in 1928. The second line of evidence is related to a possible cause-effect relationship between events within the gap. The distribution of events exhibits a coupling of earthquakes from north to south. The average inter-occurrence time is 16 ±6 years and the last quake in the northern part was in 1985. The last line of evidence arises from an analysis of all the data in this century. A southward migration of ca. 7 km/year is apparent in the sequence indicating that the possible “stress front” will arrive at the seismic gap within the first decade of the next century. The observed velocities and recurrence periods are consistent with a stress diffusion model. This analysis by no means excludes the possibility of earlier activity, such as occurred in 1971 prior to the 1985 mainshock.
KeywordsMigration Assure Beach Lithosphere Asthenosphere
Unable to display preview. Download preview PDF.
- Campos J, Kausel E (1990) The large 1939 intraplate earthquake of southern Chile. Seismol Res Lett 61:43Google Scholar
- Darwin C (1851) Geological observations on coral reefs, volcanic islands and on South America: being the geologist of the voyage of the Beagle, under the command of Captain Fitz Roy RN, during the years 1832–1836. London, 768 ppGoogle Scholar
- Fedotov SA (1965) Regularities of the distribution of strong earthquakes in Kamchatka, the Kuril Islands, and northeast Japan. Tr Inst Phys Earth Acad Sci USSR 36:66–93Google Scholar
- Gutenberg B, Richter CF (1954) Seismicity of the earth and associated phenomena, 2nd edn., Princeton University Press, Princeton, 310 ppGoogle Scholar
- Kausel E, Campos J (1989) The Ms = 8 tensional earthquake of December 9, 1950, in northern Chile and its relation to the seismic potential of the region. IASPEI Abstr p 235Google Scholar
- Lomnitz C (1983) On the epicenter of the great Santiago earthquake of 1647. Bull Seismol Soc Am 73:885–886Google Scholar
- McCann WR, Nishenko SP, Sykes LR, Krause J (1978) Seismic gaps and plate tectonics: seismic potential for major plate boundaries. In Proceedings of Conference VI. Methodology for identifying seismic gaps and soon-to-break gaps. US Geol Surv Open-File Rep 78–943: 441–584Google Scholar
- Mogi K (1969) Some features of recent seismic activity in and near Japan. Bull Earthq Res Inst Tokyo Univ 46:1225–1236Google Scholar
- Montessus de Ballore F (1911) Historia sísmica de los Andes Meridionales al Sur del Paratelo XVI. Litografía Barcelona, Santiago, vol 5, 407 ppGoogle Scholar
- Nishenko SP, McCann WR. (1981) Seismic potential for the world’s major plate boundaries. In: Simpson DW, Richards PG (eds) Earthquake prediction: an international review. Maurice Ewing Ser, vol 4, AGU, Washington D C, pp 20–28Google Scholar
- Ramírez D (1988) Estimación de algunos parámetras focales de grandes terremotos históricos chilenos. Tesis para optar al grado de Magister en Geofísica, Universidad de Chile, SantiagoGoogle Scholar
- Richter CF (1958) Elementary seismology. Freeman, San Francisco, 768 ppGoogle Scholar