Probabilistic Seismic Hazard Analysis at Regional and National Scales: State of the Art and Future Challenges

• Published in: Reviews of geophysics (1985) Vol. 58; no. 2
• Main Authors: Gerstenberger, M. C., Marzocchi, W., Allen, T., Pagani, M., Adams, J., Danciu, L., Field, E. H., Fujiwara, H., Luco, N., Ma, K.‐F., Meletti, C., Petersen, M. D.
• Format: Journal Article
• Language: English
• Published: Washington Blackwell Publishing Ltd 01-06-2020
• Subjects: Building codes; Building design; Complex systems; Computer models; Computer simulation; Decision making; Earth surface; earthquake forecast; Earthquake forecasting; earthquake hazard; Earthquake prediction; Earthquakes; Forecasting; Geological hazards; Ground motion; ground motion prediction; Hazard assessment; Information processing; Mathematical models; Modelling; NSHM; PSHA; Reviews; Seismic activity; Seismic analysis; Seismic hazard; Shaking; State-of-the-art reviews; Time dependence; Uncertainty
• ISSN: 8755-1209; 1944-9208
• DOI: 10.1029/2019RG000653

Seismic hazard modeling is a multidisciplinary science that aims to forecast earthquake occurrence and its resultant ground shaking. Such models consist of a probabilistic framework that quantifies uncertainty across a complex system; typically, this includes at least two model components developed from Earth science: seismic source and ground motion models. Although there is no scientific prescription for the forecast length, the most common probabilistic seismic hazard analyses consider forecasting windows of 30 to 50 years, which are typically an engineering demand for building code purposes. These types of analyses are the topic of this review paper. Although the core methods and assumptions of seismic hazard modeling have largely remained unchanged for more than 50 years, we review the most recent initiatives, which face the difficult task of meeting both the increasingly sophisticated demands of society and keeping pace with advances in scientific understanding. A need for more accurate and spatially precise hazard forecasting must be balanced with increased quantification of uncertainty and new challenges such as moving from time‐independent hazard to forecasts that are time dependent and specific to the time period of interest. Meeting these challenges requires the development of science‐driven models, which integrate all information available, the adoption of proper mathematical frameworks to quantify the different types of uncertainties in the hazard model, and the development of a proper testing phase of the model to quantify its consistency and skill. We review the state of the art of the National Seismic Hazard Modeling and how the most innovative approaches try to address future challenges.
Plain Language Summary
In this review paper we describe the state of the art in modeling earthquake hazard at the national scale. National hazard models take our understanding of fundamental earthquake processes and develop models of earthquake shaking relevant to the decades to come. The shaking estimates from the models provide important inputs into societal decision making across a wide range of uses including such things as building design requirements or for guiding insurance policy. Here were introduce national models from 10 regions around the world, including multinational models that aim to make results comparable from nation to nation. We describe key challenges and assumptions in making the models and provide recommendations about research for improving future generations of national models. An emerging and overriding philosophy is the need to better quantify and make useful the uncertainties in our knowledge of earthquake processes. Future models will better be able to include this uncertainty and will aim to better quantify the ability of the models to provide the outputs society needs. Finally, future models will become increasingly reliant on computer models that simulate how earthquakes interact with each other and cause shaking at the surface of the Earth.
Key Points
National Seismic Hazard Models (NSHMs) are regional models that take our understanding of earthquake occurrence and their consequent shaking intensities and make this information useful for decision makers and society
Key goals in modern probabilistic NSHMs are the improved quantification of uncertainty and research to understand the skill and usefulness of the forecasts
Current PSHA‐based methods used by NSHMs from diverse tectonic settings around the world are reviewed