Are megaquakes clustered?
Article first published online: 29 MAR 2012
This paper is not subject to U.S. copyright. Published in 2012 by the American Geophysical Union
Geophysical Research Letters
Volume 39, Issue 6, March 2012
How to Cite
2012), Are megaquakes clustered?, Geophys. Res. Lett., 39, L06308, doi:10.1029/2012GL051465., , , and (
- Issue published online: 29 MAR 2012
- Article first published online: 29 MAR 2012
- Manuscript Accepted: 5 MAR 2012
- Manuscript Received: 22 FEB 2012
- earthquake clustering;
- earthquake hazard;
- statistical seismology
 We study statistical properties of the number of large earthquakes over the past century. We analyze the cumulative distribution of the number of earthquakes with magnitude larger than threshold M in time interval T, and quantify the statistical significance of these results by simulating a large number of synthetic random catalogs. We find that in general, the earthquake record cannot be distinguished from a process that is random in time. This conclusion holds whether aftershocks are removed or not, except at magnitudes below M = 7.3. At long time intervals (T = 2–5 years), we find that statistically significant clustering is present in the catalog for lower magnitude thresholds (M = 7–7.2). However, this clustering is due to a large number of earthquakes on record in the early part of the 20th century, when magnitudes are less certain.