Conditional Probability Approach of the Assessment of Tsunami Potential: Application in Three Tsunamigenic Regions of the Pacific Ocean

Abstract

We develop stochastic approaches to determine the potential for tsunami generation from earthquakes by combining two interrelated time series, one for the earthquake events, and another for the tsunami events. Conditional probabilities for the occurrence of tsunamis as a function of time are calculated by assuming that the inter-arrival times of the past events are lognormally distributed and by taking into account the time of occurrence of the last event in the time series. An alternative approach is based on the total probabilitiy theorem. Then, the probability for the tsunami occurrence equals the product of the ratio, r (= tsunami generating earthquakes/total number of earthquakes) by the conditional probability for the occurrence of the next earthquake in the zone. The probabilities obtained by the total probability theorem are bounded upwards by the ratio r and, therefore, they are not comparable with the conditional probabilities. The two methods were successfully tested in three characteristic seismic zones of the Pacific Ocean: South America, Kuril-Kamchatka and Japan. For time intervals of about 20 years and over the probabilities exceed 0.50 in the three zones. It has been found that the results depend on the approach applied. In fact, the conditional probabilities of tsunami occurrence in Japan are slightly higher than in the South America region and in Kuril-Kamchatka they are clearly lower than in South America. Probabilities calculated by the total probability theorem are systematically higher in South America than in Japan while in Kuril-Kamchatka they are significantly lower than in Japan. The stochastic techniques tested in this paper are promising for the tsunami potential assessment in other tsunamigenic regions of the world.

Preliminary estimation of the tsunami hazards associated with the Makran subduction zone at the northwestern Indian Ocean

“…In addition, application of statistical equations linking tsunami height with earthquake magnitude may not be without deficiency, because the actual tsunami wave height at the coast would be strongly influenced by the local bathymetry and topography. Among researchers who used DSTHA are Pelinovsky (1999), Tinti and Maramai (1999), Kulikov et al (2005), Orfanogiannaki and Papadopoulos (2007).…”

Probabilistic Earthquake–Tsunami Multi-Hazard Analysis: Application to the Tohoku Region, Japan

“…The existing PTHA methods can be grouped in three broad categories. In the first category, PTHA is conducted by using tsunami catalogs (Burroughs and Tebbens, 2005;Tinti et al, 2005;Orfanogiannaki and Papadopoulos, 2007); in the second category, different scenariobased PTHA methods are suggested (Geist and Dmowska, 1999;Downes and Stirling, 2001;Farreras et al, 2007;Liu et al, 2007;Power et al, 2007;Yanagisawa et al, 2007;Burbidge et al, 2008;González et al, 2009;Løvholt et al, 2012). In the third category, a combination of the two previous categories is considered (Geist, 2005;Geist and Parsons, 2006;Annaka et al, 2007;Thio et al, 2007;Burbidge et al, 2008;Parsons and Geist, 2008;Grezio et al, 2010Grezio et al, , 2012Horspool et al, 2014;Fukutani et al, 2016).…”

Bayesian inference in natural hazard analysis for incomplete and uncertain data

“…The associated hazard increases when only the validity index is introduced. However, the introduction of prior information (Orfanogiannaki & Papadopoulos, 2007) reduces this effect ( Figure 6). The historic dataset spans more than 1,000 years compared with 50 years for the assumed instrumental dataset and, therefore, it has a larger influence on the estimates of the recurrence parameters.…”