Earthquake Rapid Warning Systems

Earthquake Rapid Warning Systems Earthquake warning AlertMap showing the predicted distribution of ground shaking for the October 30, 2007, Mw 5.4 earthquake near San Jose, California. The test system detected the earthquake and assessed the hazard before ground shaking was felt in San Francisco. Photos show the type of damage that large events, such as the 1989 Loma Prieta earthquake, have caused in the region. (Image courtesy of R. Allen.)

Before a future earthquake, you might get a warning. Maybe not much of a warning—perhaps a few seconds or a few tens of seconds at best. But it may be enough time to allow you to dive under that table, move away from that bookcase, or step back from that window. Your train could slow or stop and the highway on-ramp meter lights could turn red. Nuclear power plants could lower their control rods while refineries isolate tanks and vulnerable pipelines. With sufficient investments to link modern digital seismic networks and communication systems with decisionmaking systems and clear regulatory guidelines, a warning can be provided that comes before strong shaking starts at your location. This scenario is now plausible by very rapidly detecting earthquakes, locating and estimating their completed or potential energy release, and alerting surrounding regions after the earthquake has started but before the seismic waves reach regions away from the earthquake source. In fact, the first steps in earthquake early warning have already been taken in some parts of the world. In October 2007, Japan launched the first national earthquake warning system. The system uses a network of over 1000 seismic stations linked together to detect earthquakes ruptures automatically after they have initiated and while sliding may still be underway, and issue immediate warnings to the public. Taiwan, Turkey, Mexico, and Romania also have limited warning systems in place, and many other countries, including the United States, have prototype systems under development, but major investments will be required to make these systems operational. Dense geophysical instrumentation in earthquake source regions is required, with rapid and robust telemetry, and automated processing. Similar strategies underlie enhanced tsunami-warning systems, which exploit the fact that the sea wave generated by an underwater earthquake travels at less than the speed of a jet airplane, much slower than seismic waves traveling through rock.


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