India's Earthquake Early Warning System: A Few Seconds' Notice in the Himalayas
India does not have the technology to predict earthquakes with certainty, but it has deployed seismic monitoring networks and earthquake early warning (EEW) systems in the Himalayan region that can provide a few seconds of advance notice once a quake begins, the government informed Parliament in December.
The National Centre for Seismology (NCS) is developing and testing prototype EEW algorithms using regional data sets, focusing on reliable detection of primary waves (P-waves), rapid magnitude estimation, and early shaking prediction. P-waves travel faster than the more destructive secondary waves (S-waves) and usually cause less damage. An EEW system detects the first P-waves near the epicentre and sends alerts to locations farther off before the stronger waves arrive, giving authorities and citizens a few precious seconds to take cover or activate emergency protocols.
The most successful effort in extending EEW in India has been led by IIT Roorkee in collaboration with the Uttarakhand government. They developed an app called BhuDEV, a cutting-edge early warning system that leverages technology to enhance safety and resilience against seismic threats. Sensor networks are primarily installed in the Garhwal and Kumaon regions of Uttarakhand, placed close to active fault zones. When these sensors detect P-waves, alerts can be transmitted to downstream cities before stronger tremors arrive.
The available warning time depends on the distance from the epicentre. Near the epicentre, there is little or no warning, but locations hundreds or thousands of kilometres away may have a margin of a few seconds. This limited window is nonetheless valuable for automated systems like trains, elevators, and gas lines to shut down, and for people to drop, cover, and hold on.
India's system is part of a global effort. Japan, Taiwan, and the United States have some of the most advanced EEW systems, providing few seconds to tens of seconds of warning. While India's system is still evolving, it represents a significant step in disaster preparedness for the seismically active Himalayan region.
It is important to note that early warning is not earthquake prediction. Scientists cannot predict the exact time and place of a quake. EEW systems only work after an earthquake has started, using the time lag between P-waves and S-waves to alert distant areas. Continued investment in sensor networks and public education is essential to maximize the life-saving potential of these systems.
