Many parts of the Indian Himalayas fall into highly seismic zones that are prone to dangerous tremors. The Indian plate is rubbing against the Eurasian plate at a rate of 5 centimeters per year. This draw, while slow and painful, soaks the region with frequent earthquakes that eventually cause widespread destruction of life and infrastructure.
But a new study has shown that there may be another silent killer lurking in these cracks that we haven’t adequately explained. Satellite observations have revealed that even weak tremors can trigger strong landslides during seismic activity. Amazingly, this can happen even years after the initial tremors shake the area, debunking the myth that an area becomes safe only after enough time has passed.
25% of tragic losses during earthquakes in hilly terrains
The study focused specifically on earthquake-accelerated landslides, which can harbor accelerated motion from an earthquake in an area long after the tremors have passed. In earthquake-prone areas, the result is usually severe loss of life. In fact, studies show that about 25% of tragic losses during earthquakes in hilly terrains such as the Himalayas or the North-East range can be attributed to subsequent landslides that hit the area. Add to that the fact that these regions also receive large amounts of rainfall for about half of the year, further increasing the risk of landslides.
The current hope is that this new observation may help with better preparedness for such natural disasters. Every year we lose about 18,000 lives worldwide due to landslides, with about 50 million people affected. In India alone, landslides have claimed nearly 3,500 lives over the past decade. These are extremely high numbers, and preventive mitigation measures could serve to significantly reduce them.
Professor Utili, from Newcastle University’s School of Engineering, explains: “This study presents a cost-effective and efficient methodology based on satellite imagery to identify and assess the risk posed by ground motions that will become catastrophic landslides after an earthquake in the long term. The next steps will be on the civil authorities to adopt the methods.”
