Understanding Extreme Geohazards: The Science of the Disaster Risk Management Cycle

European Science Foundation Conference
November 28 to December 1, 2011, Sant Feliu de Guixols, Spain

The 'M9 Conundrum' - why the most critical earthquakes are also the most illusive

Robert Muir-Wood
Risk Management Solutions, London. United Kingdom, robertm@rms.com

The occurrence of the Tohoku earthquake in Japan has shaken confidence in earthquake hazard methodologies around upper bound magnitudes. Two M9 earthquakes have occurred in the European region in history: along the Hellenic Arc subduction zone in 365AD and in 1755 to the southwest of Iberia. Whether M9 earthquakes can occur along a particular active or incipient subduction zone has enormous importance for earthquake, tsunami and critical facility risk management. Should we rather start with the question - where can M9 earthquakes NOT occur?