The Hindu : Kerala News : C-DAC develops quake-warning system

Online edition of India's National Newspaper
Friday, Feb 10, 2006

Kerala

Kerala

C-DAC develops quake-warning system

T. Nandakumar

Seismic fence can identify harmless seismic waves that precede a quake

MAJOR DEVELOPMENT: K.R. Rajesh who led a team of young scientists to develop the sensor; (right) the equipment developed by the team.

Thiruvananthapuram: A team of young scientists attached to the Centre for Development of Advanced Computing (C-DAC) here has developed a low-cost sensor-based system for early warning of earthquakes.

The system is designed to identify the harmless seismic waves that precede the destructive force of an earthquake and provide enough advance warning to shut down vulnerable facilities.

Team leader scientist K.R. Rajesh won the Young Scientist Best Paper award in Engineering and Technology at the 18th Kerala Science Congress held here in January.

He has applied for a patent on the device. A prototype has been successfully tested and an engineered version is on the drawing board.

Named seismic fence, the system uses state-of-the-art sensors and a high-speed digital signal processor to identify the precursor of the destructive waves of an earthquake.

The seismic sensor used in the device was conceptualised and built at the Strategic Electronics Group, C- DAC. It is based on a MEMS (Micro Electro Mechanical Systems) platform.

According to Mr. Rajesh, the system is capable of providing an advance warning of 20 seconds for an earthquake originating 200 km away.

"Those few moments would enable vital installations such as atomic power plants and oil refineries to be shut down. It could also save human lives," he adds.

When an earthquake occurs, energy radiates outward in all direction from the epicentre. It travels through and around the earth as three types of seismic waves, namely primary, secondary and surface waves.

P (primary) waves are the fastest while surface waves are the slowest and most destructive. Both the P and S (secondary) waves have such small energies that are not threatening.

The seismic fence is designed to detect the precursor waves to predict the arrival of the damaging surface waves.

The ground vibration signals are acquired using a sensitive accelerometer and analysed by a digital processor.

Alarm system

The system activates an alarm when the signal crosses a pre-set threshold. The Richter magnitude and epicentre distance of the incoming earthquake can also be calculated.

Developed at a cost of $100,the prototype was extensively tested with simulated signals and using vibration test facility at the Electronics Regional Test Laboratory, Thiruvananthapuram.

It was also exposed to noisy environment such as vehicle and rail traffic and quarries to rule out false alarms.

Mr. Rajesh said the cost of the seismic fence could be brought down in the production stage. The system can also be upgraded with more sophisticated components such as geophones.

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