Defining an Earthquake Intensity Based Method for a Rapid Earthquake Classification System

Sammanfattning: Ground motions caused by earthquakes may be strong enough to cause destruction of infrastructure and possibly casualties. If such past destructive earthquakes are analysed, the gained information could be used to develop earthquake warning systems that predicts and possibly reduce the damage potential of further earthquakes. The Swedish National Seismic Network (SNSN) runs an automated early warning system that attempts to predict the damage of an earthquake that just got recorded, and forward the predictions to relevant government agencies. The predictions are based on, e.g. earthquake magnitude, source depth and an estimate of the size of affected human population. The purpose of this thesis is to introduce an additional parameter: earthquake intensity, which is a measure of the intensity with which the ground shakes. Based on this, a new earthquake hazard scheme, the Intensity Based Earthquake Classification (IBEC) scheme, is created. This scheme suggests alternate methods, relative to SNSN, of how earthquake classifications can be made. These methods will use an intensity database established by modelling scenario earthquakes in the open-source software ShakeMap by the U.S. Geological Survey. The database consists of scenarios on the intervals: 4.0 ≤ Mw ≤ 9.0 and 10 ≤ depth ≤ 150 kilometre, and covers the whole intensity scale, Modified Mercalli Intensity, 1.0 ≤ Imm ≤ 10.0. The IBEC classification scheme also enabled the creation of the 'Population-to-Area' criterion. It improves prediction of earthquakes that struck isolated cities, located in e.g. valleys in large mountainous areas and deserts. Even though such earthquakes are relatively uncommon, once they occur, they may cause great damage as many cities in such regions around the world often are less developed regarding resistance to ground motions.