Earthquakes usually strike without warning and cause massive landslides, bring down even earthquake-resistant structures, and cause major fires. People get trapped under collapsed buildings, fires are caused due to broken gas mains, anti-social activities especially looting of property can occur. Also, buildings that have remained intact or partially damaged need to be stabilized so that they do not collapse in the aftershocks that follow. To initiate rescue operations, Civil defense organizations need to get their disaster control centers immediately into the act.
Most of the hazards to people come from man-made structures. Liquefaction occurring underneath a building can make the building lean, or collapse, or sink several feet (UPSeis – MichiganTech, 2007) (Fig. 1). Hence, liquefaction is a risk especially in areas where the groundwater table is high and the soil is sandy. Also, the strong surface waves generated by an earthquake can make the ground heave and lurch, and thereby cause damage to buildings.
Another major earthquake hazard is a fire due to broken gas lines and snapped power lines. The Great San Francisco Earthquake of 1906 made the city burn for three days (Fig. 2), and destroyed most of the city. Flooding due to cracking of dams and levees is yet another major earthquake hazard.
The recent earthquake in Japan, the Chile earthquake of 2010 and the earthquake off Sumatra- Indonesia in 2004 were some of the earthquakes in recent times that caused immense havoc through the generation of tsunamis (Fig. 3A and B). In the Japan earthquake, the huge tsunami waves reaching up to 33 feet in some places reached nearly 6 miles (10 kilometers) inland in Miyagi Prefecture (National Geographic Daily News).
It is not possible to ascertain if a volcano has become extinct. A volcano that lay dormant for 5000 years erupted in 1973 on Heimaey island near Iceland (USGS, 1983). Furthermore, the eruption of volcanoes can neither be prevented nor controlled.