| Popis: |
The question of time-dependent seismic hazard models is still an open one. While most hazard studies assume stationarity of seismicity, there has been some debate on the relative merits of Poissonian and non-Poissonian recurrence models, and opinions about the viability of the seismic gap hypothesis also vary. Previous attempts to treat seismic hazard as time-dependent have, however, concentrated on large earthquakes, which do not always control the hazard at a site. In this study, earthquake interarrival times are studied for several regions in Japan and Greece. It is found that a lognormal distribution provides a good model and that seismicity can be represented by the equation ln IAT = a + b M ± c where ln IAT is the log interarrival time of earthquakes exceeding magnitude M and a, b , and c are regional constants. This power law is clearly related to the normal Gutenberg-Richter magnitude-frequency law, but actually contains more information. This law provides a basis for time-dependent seismic hazard analysis in which the whole earthquake catalog is used, rather than just the largest events. A question still remains as to whether c (the standard deviation) is significantly dependent on magnitude. Manuscript received 10 January 2000. |
