Natural Disaster. "An earthquake is a sudden and rapid shaking of the earth caused by the breaking and shifting of rock beneath the earth's surface. This shaking can sometimes trigger landslides, avalanches, flash floods, fires and tsunamis. Unlike other natural disasters such as hurricanes, there are no specific seasons for earthquakes.... In the United States about 5,000 quakes strike each year. Since 1900 earthquakes have occurred in 39 states and caused damage in all 50.... The potential cost of earthquakes has been growing because of increasing urban development in seismically active areas and the vulnerability of older buildings, which may not have been built or upgraded to current building codes..... only about 12 percent of homeowners in California now buy earthquake coverage..... In April 2008 experts from the U.S. Geological Survey, USC's Southern California Earthquake Center and the State Geological Survey released an earthquake forecast indicating that a huge quake is far more likely in Southern California than in Northern California in the next 30 years. The report also concluded that the state is virtually certain to be hit by a major earthquake by 2028. The researchers found that the chance of a 6.7 magnitude temblor, equal to the 1994 Northridge quake, is 97 percent in Southern California and 93 percent in Northern California. The likelihood of a 7.5 quake, which is 16 times more intense than a 6.7 quake, is 37 percent in Southern California and 15 percent in Northern California. The study used new information about prehistoric earthquakes, locations of faults and their slip rates, and satellite data of the movement of the Earth's crust to calculate the likelihood of earthquakes in the state. Thomas Jordan, director of the Southern California Earthquake Center, said that both the data and the method of its collection have been improving. The report will be used to update seismic hazard maps that warn residents and local governments about areas at highest risk of property damage and loss of life". (III, Earthquakes: Risk & Insurance Issues, May 2008)