Annual modulation of triggered seismicity following the 1992 Landers earthquake in California

Citation
Ss. Gao et al., Annual modulation of triggered seismicity following the 1992 Landers earthquake in California, NATURE, 406(6795), 2000, pp. 500-504
Citations number
13
Categorie Soggetti
Multidisciplinary,Multidisciplinary,Multidisciplinary
Journal title
NATURE
ISSN journal
00280836 → ACNP
Volume
406
Issue
6795
Year of publication
2000
Pages
500 - 504
Database
ISI
SICI code
0028-0836(20000803)406:6795<500:AMOTSF>2.0.ZU;2-Y
Abstract
The mechanism responsible for the triggering of earthquakes remains one of the least-understood aspects of the earthquake process. The magnitude-7.3 L anders, California earthquake of 28 June 1992 was followed for several week s by triggered seismic activity over a large area, encompassing much of the western United States(1). Here we show that this triggered seismicity mark ed the beginning of a five-year trend, consisting of an elevated microearth quake rate that was modulated by an annual cycle, decaying with time. The a nnual cycle is mainly associated with several hydrothermal or volcanic regi ons where short-term triggering was also observed. These data indicate that the Landers earthquake produced long-term physical changes in these areas, and that an environmental source of stress-plausibly barometric pressure-m ight be responsible for the annual variation.