Recurrence Periods of Earthquake-Induced Submarine Landslides

Wednesday, 17 December 2014: 10:20 AM
Rafael Rodríguez-Ochoa1 and Farrokh Nadim1,2, (1)University of Oslo, Geosciences, Oslo, Norway, (2)Norwegian Geotechnical Institute, Landslides and Georisk, Oslo, Norway
Submarine landslides represent a constant threat to offshore installations deployed along the continental slope, therefore the estimation of the recurrence period of slope failures is a key parameter to assess the risk associated with potential massive transport of soil sediments. The initiation of submarine slope failures may be due to long-term triggers like the formation of weak layers, sedimentation rates and fault displacements, as well as short-term triggers like earthquakes and storm waves, or a combination of both of them.

The recurrence period of submarine slope failures can be linked to the recurrence period of their triggers. When the main trigger of slope failure is an earthquake, it is possible to estimate numerically the probability density of the return period for slope failure by using the seismic hazard curve and a mechanical model for earthquake-triggered slope instability.

This paper presents a procedure to calculate the conditional probability of slope failure with the maximum probability density (peak) to obtain the return period of the earthquake event with the largest probability of inducing a slope failure. The conditional probability corresponding to the maximum probability density is estimated after obtaining several conditional cumulative probability points for different earthquake return periods, and matching a cumulative distribution function (CDF) to those points; finally, the maximum probability density of the corresponding probability density function (PDF) is obtained.

The suggested analytical procedure is applied and compared with available geological evidence in a site located in the Gulf of Mexico.