Chapter 2 Seismic hazard

Abstract It is often thought that earthquakes do not occur in the UK; however, the seismicity of the UK is usually classified as low-to-moderate. On average, a magnitude 3.2 Mw moment magnitude or larger earthquake occurs once per year, and 4.2 Mw or larger every 10 years. The latter is capable of causing non-structural damage to property. The damage caused by British earthquakes is generally not life-threatening, and no-one has been killed in a British earthquake (at the time of writing, May 2013) since 1940. Damage is caused by shaking, not by ground rupture, so the discovery of a fault surface trace at a construction site is not something to be worried about as far as seismic hazard is concerned. For most ordinary construction in the UK, earthquake hazard can be safely discounted; this is not the case with high-consequence facilities such as dams, bridges and nuclear power plants.