Geohazard Risk Assessment and Seismicity

Abstract

Abstract Major infrastructure projects in marine environments are exposed to a wide range of geological and seismic hazards, and invariably these projects benefit from careful consideration of their unique geological conditions. In offshore projects, it is necessary to characterize hazards during all phases of a project as understanding the nature of a hazard can enable steps to be taken that can reduce the risk to the system. Risk is the product of three important parameters, including geological hazard, structural vulnerability, and consequence. There are five general types of geological or seismic hazards, including (i) surface fault rupture, (ii) strong ground shaking, (iii) liquefaction‐related ground deformation, (iv) seismically induced slope failure, and (v) tsunami. Ground motion hazards can be assessed using the probabilistic seismic hazard analyses (PSHA) approach. This approach is particularly useful in characterizing the hazard because the results are presented in terms of an annual frequency of exceedance, or frequency of occurrence, which is one of the primary factors necessary to consider hazards in a risk‐based framework. Performing a PSHA requires two basic inputs that describe earthquake sources and the transmission of seismic energy through the earth's crust: the seismic source model and the ground motion model. Treatment of uncertainty is a critical part of developing these inputs.