By Dhiman Ranjan Mondal, Post-Doctoral Research Scientist at Haystack Observatory, Massachusetts
[...]
The state of California in the USA recently introduced an early alert system that is designed to send alerts over a cell phone network after detecting any seismic activity. A cell phone application was released which will alert the user if an earthquake of magnitude 5 or higher is detected. The earthquake system installed in CA, USA is comprised of a dense network of 600 seismometers and efficient and very fast computer programmes. The principle behind this system follows simple seismological laws. When an earthquake occurs it produces two types of seismic waves, P-wave and S-wave. P-wave travels much faster than S-wave. But, the latter causes more damage than the former. Telecommunication signal travels faster than these two types of seismic waves, at a speed of light. Thus, the idea behind this alert system is to capture the shaking from P-wave using multiple seismographs from near the source (as close as possible), process the signal to calculate preliminary magnitude, predict which area will feel the jolts and issue an alert. It gives people up to 10s of seconds to prepare and to make possible life-saving actions which of course depends on the distance between the source and the seismograph. Several countries have developed a similar system before this; Canada developed the early warning spending about 5 million Canadian dollars.
[…]
A comprehensive alert system similar to this is much needed for Bangladesh, given that Bangladesh is located in the vicinity of two major tectonic faults, along the Himalayan range in the north and Indo-Burma range in the east. There will be some limitations but the government should start thinking now about developing an earthquake alert system. P- and S-wave travel at the rate of roughly 5.6 km and 3.2 km, every second. Therefore, P-wave generated from an earthquake occurred 100 km away will reach Dhaka city in 17 seconds, and the following S-wave will reach in 34 seconds. If an earthquake can be detected near the source, for example, 100 km away, the city will get about 30 seconds to prepare, assuming that there are some ways to send signals through high-speed communication. Further away the city is from the epicentre, the more time the city will have between the warning and the jolts, thus more time to be prepared.
[…]
Different institutions in Bangladesh such as Dhaka University Earth Observatory (DUEO), Bangladesh University of Engineering and Technology (BUET), Geological Survey of Bangladesh (GSB) and Bangladesh Meteorological Department (BMD) operate seismic monitoring networks separately. BUET and AIUB have conducted a study on developing electronics for earthquake early warning system. A collective effort is needed to develop proper hardware, software, and scientific objectives to implement such a project. Given that, BMD already has a network with operational seismograms and communication network, a pilot project can be conducted as a kick-off.
[...]