HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Figures Only Full Text Full Text (PDF) Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via ISI Web of Science (20) Citing Articles via Google Scholar Google Scholar Articles by Felzer, K. R. Articles by Ekström, G. Search for Related Content GeoRef GeoRef Citation

Secondary Aftershocks and Their Importance for Aftershock Forecasting

Department of Earth and Planetary Sciences
Harvard University
20 Oxford St.
Cambridge, Massachusetts 02138
(K.R.F., G.E.)
Department of Earth Sciences
Boston University
685 Commonwealth Ave.
Boston, Massachusetts 02215
(R.E.A.)

Manuscript received 20 November 2002.

The potential locations of aftershocks, which can be large and damaging, are often forecast by calculating where the mainshock increased stress. We find, however, that the mainshock-induced stress field is often rapidly altered by aftershock-induced stresses. We find that the percentage of aftershocks that are secondary aftershocks, or aftershocks triggered by previous aftershocks, increases with time after the mainshock. If we only consider aftershock sequences in which all aftershocks are smaller than the mainshock, the percentage of aftershocks that are secondary also increases with mainshock magnitude. Using the California earthquake catalog and Monte Carlo trials we estimate that on average more than 50% of aftershocks produced 8 or more days after M 5 mainshocks, and more than 50% of all aftershocks produced by M 7 mainshocks that have aftershock sequences lasting at least 15 days, are triggered by previous aftershocks. These results suggest that previous aftershock times and locations may be important predictors for new aftershocks. We find that for four large aftershock sequences in California, an updated forecast method using previous aftershock data (and neglecting mainshock-induced stress changes) can outperform forecasts made by calculating the static Coulomb stress change induced solely by the mainshock.

This article has been cited by other articles:

				M. C. Gerstenberger, L. M. Jones, and S. Wiemer Short-term Aftershock Probabilities: Case Studies in California Seismological Research Letters, January 1, 2007; 78(1): 66 - 77. [Full Text] [PDF]

				A. Ziv What Controls the Spatial Distribution of Remote Aftershocks? Bulletin of the Seismological Society of America, December 1, 2006; 96(6): 2231 - 2241. [Abstract] [Full Text] [PDF]

				R. Shcherbakov, D. L. Turcotte, and J. B. Rundle Scaling Properties of the Parkfield Aftershock Sequence Bulletin of the Seismological Society of America, September 1, 2006; 96(4B): S376 - S384. [Abstract] [Full Text] [PDF]

				A. Ziv On the Role of Multiple Interactions in Remote Aftershock Triggering: The Landers and the Hector Mine Case Studies Bulletin of the Seismological Society of America, February 1, 2006; 96(1): 80 - 89. [Abstract] [Full Text] [PDF]

				A. Helmstetter, Y. Y. Kagan, and D. D. Jackson Comparison of Short-Term and Time-Independent Earthquake Forecast Models for Southern California Bulletin of the Seismological Society of America, February 1, 2006; 96(1): 90 - 106. [Abstract] [Full Text] [PDF]