Investing $20 million to set up earthquake early warning system based on real time seismology may be a huge amount for Nepal at this stage when it faces the daunting challenge of rehabilitation and reconstruction, but experts say it is a worthwhile investment.

Geophysicist Subesh Ghimire said if super computers were set up and if sophisticated broadband seismometers were installed across the country, it would roughly cost $ 20 million, but that could save lives when powerful earthquakes occur.

The system helps alert the public immediately when a quake hits a region and people have a few more seconds to run for safety.

Engineering Geologist Sunil Kumar Dwivedi echoed Ghimire. “We are a quake-prone country, and after seeing the devastation caused by the April 25 earthquake, the government must seriously think of installing earthquake early warning system,” he added.

When a powerful earthquake, Ghimire said, hits a region, it releases primary (P) and Secondary (S) waves as body waves. P-waves propagate faster than S-waves, such that the time lag between the arrivals of S- and P-waves ranges from one to two seconds to a couple of minutes depending upon the epicentral distance. In real time seismology, P-waves are called information carriers and the most powerful and devastating S-waves are called energy carriers. “Earthquake early warning system calculates the magnitude and intensity of the quake in one to two seconds using P-waves and alerts the public about the duration of the quake and its intensity. Yet such dissemination may not give enough time to the residents in epicentre areas (zero time region) to run for safety, people away from the epicentre area will have at least a few seconds to run for safety or move to safer places before the devastating energy shakes the ground,” Ghimire said.

The system electronically transmits real time information about earthquakes. “Such information can be transmitted immediately through mobile phones and telephones and other electronic devices,” he said.

Dwivedi said had Nepal had earthquake early warning system, it could have lessened the loss of life caused by the April 25 quake and its aftershocks.

This system also helps alert high speed trains to stop immediately and avoid casualties. “This system has proved very useful in Japan, particularly for high speed trains that run 300-400 km/hour,” Ghimire added.

Ghimire said the government needed to inform the public about earthquakes through formal and informal education. “Those who have enough knowledge about earthquakes will not unnecessarily panic,” he said.

Chief of National Seismological Centre Lok Bijaya Adhikari said his office was thinking of installing earthquake early warning system, but it might not be as useful as in Japan.

“In Japan, earthquakes normally happen under the sea which is far from the mainland. Japan thus has an advantage of disseminating real time earthquake warning early,” he said. According to him, Japan has almost 4,000 earthquake early warning stations in the mainland and under the sea.

Adhikari said in Nepal, cities and villages are close to areas where earthquakes occur, therefore, even if earthquake early warning system was installed, it might not be as useful as in the case of Japan.

“Besides, it may not be difficult to install the system initially but maintaining it could be more expensive,” he said.

source:the himalayan times,20 may 2015