Physical Care: Lessening Impacts from Other Natural Hazards

Abstract

Earthquakes happen by the thousands each year but only a small number annually release the seismic energy that can kill and injure people and damage and destroy structures and infrastructure. A regional recurrence interval for major earthquakes as well as the probable Richter scale magnitude can only be very roughly estimated (guesstimated?). For example, the United States Geological Survey gives probabilities of high magnitude earthquakes hitting the Los Angeles and San Francisco areas in 30 years. For Los Angeles, there is a 60% probability that there will be an earthquake of 6.7 (destructive) magnitude. For San Francisco, there is a 72% probability that there will be a 6.7 magnitude earthquake. Whatever the weakness in prediction and the inability to prevent an earthquake, locations must prepare so as to limit an earthquake impact on citizens and assets. The probabilities that greater magnitude earthquakes will hit the two California areas are given in Table 5.1. Other countries at risk of earthquakes in coastal cities make similar estimates. For example, 2012 data from Tokyo University Earthquake Research Institute gave a probability of 70% for a magnitude 7 earthquake impacting Tokyo in 4 years. It did not happen. A prediction of a 98% probability in 30 years, 2042, has 23 years to occur or not.