Quick Search:    advanced search

GSW Home   GeoRef Home   My GSW Alerts   Contact GSW   About GSW   Journals List   Help

This Article Full Text (PDF) References Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Nostro, C. Articles by Belardinelli, M. E. Search for Related Content GeoRef GeoRef Citation

Static stress changes in extensional regimes: An application to southern Apennines (Italy)

Istituto Nazionale di Geofisica, Via di Vigna Murata, 605, 00143 Rome, Italy

Abstract

The analysis of static stress changes due to co-seismic dislocations has been widely applied in recent years to study the variation in failure stress on well-known segmented seismogenic faults. These studies assert that earthquakes induce changes in static stress on neighboring faults that may delay, advance, or trigger impending earthquakes. So far, most of the investigations have focused on California strike-slip faults and, more recently, on thrust faults. In this work, we study the static stress changes in an extensional tectonic setting. Following Okada (1992), we calculate static stress changes caused by normal-faulting earthquakes in the southern Apennines (Italy) using a 3D dislocation model in an elastic half-space. We first studied the static stress changes produced by the 1980 Irpinia earthquake. This normal-faulting event consisted of four fault segments that ruptured together within 40 sec. The last two subevents occurred 20 and 40 sec after the nucleation on two normal faults parallel to the main one. Because the rupture of these subvents are separated by a sufficiently long time interval, we assume that, before each subevent, the dynamic stress has reached its static configuration. Therefore, we analyze the static stress changes caused by each subevent in order to determine the variations of the initial conditions for subsequent ruptures. Moreover, we applied our procedure to study the static stress changes after the 1980 Irpinia earthquake on the fault zone where the 1990 and 1991 Potenza earthquakes (M 5) occurred. Our calculations indicate that, even if the amount of stress change depends on the fault geometry assumed for the 20-sec subevent of the Irpinia fault, the static stress increased on the Potenza fault after the 1980 Irpinia earthquake. This event also increased the static stress on seismogenic faults that are believed to have ruptured in the 1732 and 1857 earthquakes (M 6.5). In these calculations, we have considered the effect of a regional extensional stress field whose minimum principal axis is horizontal and oriented 216° N. The results show that the 1980 Irpinia earthquake increased the static stress by roughly 1 bar on the 1732 fault zone. Right lateral strike-slip faults oriented nearly E-W, such as the Potenza fault, are favorably oriented with respect to the total stress resulting from the extensional regional stress field and the coseismic stress induced by the Irpinia earthquake. Finally, we investigate the static stress changes caused by several historical earthquakes that occurred along the southern Apennines seismogenic belt. Most of the large historical earthquakes occurred in areas of static stress increase, yielding evidence for fault interaction.

This article has been cited by other articles:

				D. S. Brothers, G. M. Kent, N. W. Driscoll, S. B. Smith, R. Karlin, J. A. Dingler, A. J. Harding, G. G. Seitz, and J. M. Babcock New Constraints on Deformation, Slip Rate, and Timing of the Most Recent Earthquake on the West Tahoe-Dollar Point Fault, Lake Tahoe Basin, California Bulletin of the Seismological Society of America, April 1, 2009; 99(2A): 499 - 519. [Abstract] [Full Text] [PDF]

				P. Burrato and G. Valensise Rise and Fall of a Hypothesized Seismic Gap: Source Complexity in the Mw 7.0 16 December 1857 Southern Italy Earthquake Bulletin of the Seismological Society of America, February 1, 2008; 98(1): 139 - 148. [Abstract] [Full Text] [PDF]

				D. Di Bucci, B. Massa, and A. Zuppetta Relay ramps in active normal fault zones: A clue to the identification of seismogenic sources (1688 Sannio earthquake, Italy) Geological Society of America Bulletin, March 1, 2006; 118(3-4): 430 - 448. [Abstract] [Full Text] [PDF]

				Stress Triggering of Conjugate Normal Faulting: Late Aftershocks of the 1983 Ms 7.3 Borah Peak, Idaho, Earthquake Bulletin of the Seismological Society of America, June 1, 2004; 94(3): 828 - 844.

				A Model of Tectonic Stress State and Rate Using the 1994 Northridge Earthquake Sequence Bulletin of the Seismological Society of America, April 1, 2001; 91(2): 263 - 275.