Earthquake

An earthquake (also known as a tremor or temblor) is the result of a sudden release of energy in the Earth's crust that creates seismic waves. Earthquakes are recorded with a seismometer, also known as a seismograph. The moment magnitude of an earthquake is conventionally reported, or the related and mostly obsolete Richter magnitude, with magnitude 3 or lower earthquakes being mostly imperceptible and magnitude 7 causing serious damage over large areas. Intensity of shaking is measured on the modified Mercalli scale.

At the Earth's surface, earthquakes manifest themselves by shaking and sometimes displacing the ground. When a large earthquake epicenter is located offshore, the seabed sometimes suffers sufficient displacement to cause a tsunami. The shaking in earthquakes can also trigger landslides and occasionally volcanic activity.

In its most generic sense, the word earthquake is used to describe any seismic event—whether a natural phenomenon or an event caused by humans—that generates seismic waves. Earthquakes are caused mostly by rupture of geological faults, but also by volcanic activity, landslides, mine blasts, and nuclear experiments. An earthquake's point of initial rupture is called its focus or hypocenter.

Seismometer are used by seismologists to measure and record seismic waves.
There also exist an earthquake detection system such as California's earthquake warning system is rather lackluster, especially if compared to similar programs.

California scientists are developing a new earthquake warning system that theoretically would be able to save lives, they said during the American Geophysical Union conference. Even though current tests are becoming more realistic, major upgrades and more seismic monitoring stations need to be built before something can become the official warning system for California.

Scientists are researching systems designed to provide valuable seconds and possibly minutes of warning before large earthquakes strike. Earthquake safety experts tell DailyTech a mere 10 to 15 seconds could be the difference between life or death if a strong earthquake occurs somewhere in California.

With help using software written by UC Seismological Lab's Richard Allen, scientists can detect tremors seconds before they occur and are felt. For example, during a 5.4 magnitude earthquake in the California Bay Area on Oct. 30, Allen's software was able to pick up "ground-shaking capability" fast enough to alert people in several Bay Area cities. He plans to keep testing the system until July 2009, but said much work still must be done before the software can be implemented.

Also during AGU, representatives of 14 European Union nations reported success with test systems in three European nations. In one of the test cities, Bucharest, nuclear power plants are able to receive up to 35 seconds of notice before a a large earthquake strikes.

Japan, a nation often ravaged by strong earthquakes, recently implemented a system able to provide warning to public buildings and government offices.

The U.S. Geological Survey also was present at AGU to discuss how government agencies are creating technology to test the feasibility of warning systems in California and across the nation. The USGS and California Integrated Seismic Network (CISN) are evaluating three different algorithms, including Allen's, to determine their effectiveness. Both agencies are carefully seeing how systems in Japan, the EU, Mexico and Taiwan, which help evaluate what kind of technology setups they can implement.