UrEDAS, the Earthquake Warning System: Today and Tomorrow

Abstract

The most important countermeasure against earthquake risk is to have all structures vulnerable enough for the possible earthquake load. In this regard, an early warning system should be installed to reduce the possibility of earthquake disaster. An early warning system is required mainly to issue an alarm to have a time margin for evacuating or shutting down key facilities, and not to determine exact earthquake parameters. Thus the early warning system must be realized independently and the government and other public authorities must release accurate earthquake information immediately.

The necessary qualities for early warning systems may be summarized as follows:

• Fully Automated: As the time margin is limited, the facility should be directly controlled without human judgment.

• Quick and Reliable: As there is limited time to respond to earthquake motion, this kind of system is required to be quick and reliable.

• Small and Cheap: To install easily, the system must be small and cheap.

• Independence: To issue fail-safe alarms, the system must be independent of other systems.

• Easy to Connect Network: To deliver the earthquake information, the system must be easy to connect network.

• Accuracy is Better: For the alarm, accuracy of the information is not such a serious problem.

UrEDAS, Urgent Earthquake Detection and Alarm System, is the first real-time P-wave alarm system in practical use in the world. It is able to process digitized waveforms step by step without storing the waveform data. As the amount of processing does not differ whether or not an earthquake occurs, system failure due to overload will not occur.

Here, the present condition of the P-wave early detection system UrEDAS is viewed under working conditions and the results of test observations where faults exist are also reported. Then a new real-time data processing system for new generation will be considered.