Unlike Latur in 1993, which took quake experts by surprise by occurring in an area seen as seismically serene, this tremblor was consistent with received knowledge and, thus, not completely unexpected. It occurred in a region known for its seismic vulnerability—clocking major earthquakes of intensity going over 7 on the Richter at least once in 50 years, interspersed with frequent minor ones.
Indeed, the earliest recorded quake in Gujarat—in 1819, at 8 on the Richter—happened here. It’s said to have flattened entire villages, including a monument called the Sindree Fort, and crushed 3,500 people. But most famously, it ripped the earth apart and created a 140-km-long scarp—an elevation of bunched-up soil—in the Little Rann of Kutch. Awestruck mortals dubbed it Allah Bund.
Not that scientists can explain things much better. Experts at the Indian Meteorology Department (imd) believe the Bhuj quake is a reawakening of the Allah Bund fault. "Maybe so," says H.K. Gupta, chief of Hyderabad’s National Geophysical Research Institute (ngri), "but the rupture of any one of many faults in the region could have triggered it." He, for one, plumps for the notorious Narmada-Sone lineament, which runs through central India and has been implicated in many earthquakes, the latest being the 1997 Jabalpur tremors.
The magnitude is also contentious. The imd declared 6.9 Richter in its first readings from monitoring stations in Bhuj, Bhopal and Pune. Other observatories around the world reported 7.9. Gupta feels both are right as the two readings represent two kinds of waves—body waves, which the imd recorded, and surface waves, recorded by others. He admits it is surface waves that are always used to measure the magnitude of big quakes. The latest analysis of recordings from 80 labs revised it to 8.0.
The rest of the story is commonplace. The Indian plate is constantly pushing against the Eurasian one, creating tectonic tension that spreads out over the Indian landmass. This accumulating stress can make faults slip and trigger quakes. Scientists can’t predict a quake but destruction can be mitigated with quake-resistant buildings. The ngri has prepared a seismic hazard map of India. The next step is to translate this into risk, which can then be managed. The Centre has been dragging its feet. Only now, says Gupta, has the dst begun a project in Jabalpur, which should be replicated in all quake-prone areas. The Bureau of Indian Standards has prepared guidelines for constructions in quake-prone zones. It’s not too late to enforce them. For, the next one could be even more catastrophic.