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Since 2000 AD, more than 600,000 people have died in earthquakes, and reconstruction costs in industrialized nations have exceeded $300 billion. But the experiences and consequences of earthquakes around the world are very varied. Four of the ten largest earthquakes since 1900 have happened in the last decade; but these are not the earthquakes responsible for killing the most people (excluding the effects of tsunamis). Many more people die in moderate-sized earthquakes in the interior of continents, particularly in Asia, than in the largest earthquakes, which occur on the margins of the oceans. The reasons for this are partly geological: earthquakes on ocean margins are localized on well-defined faults that move relatively frequently, whereas earthquakes on continents are widely distributed on thousands of faults that move rarely and are often unknown before they move. Consequently, much larger areas are vulnerable on the continents, often with dense urban populations concentrated in dangerous locations (usually chosen because of favourable geological circumstances, such as the control of water supply or access to trade routes) that have been destroyed by forgotten earthquakes in the past. But it is falling buildings and landslides that kill people, not the earthquakes themselves, and variations in building quality are mostly responsible for the contrast between relatively resilient places like Japan, New Zealand, Chile and California and the more vulnerable countries like India, Pakistan, Iran and China. What can be done to improve the situation in vulnerable countries in Asia? It is important to recognize that this is not a problem that can be ‘solved’ by scientists. Earthquake prediction is not possible on a useful timescale, and it is not the reason fewer people die in developed nations. Resilient nations are those where scientists can provide a realistic assessment of earthquake hazard, which is then understood by politicians, engineers, and planners who work with the scientists to educate the public.This requires everyone to take responsibility, to collaborate and, especially, it requires a vigorous and healthy activity in modern earthquake science. Realistic earthquake hazard assessment needs work by geologists and seismologists to identify and characterize earthquake-generating faults and their historical activity and to understand their effect on the landscape. A recent example of the role of modern earthquake science in hazard assessment is the 2015 Gorkha (Nepal) earthquake, where within a few days of the event it was clear from the scientific analysis that the earthquake had not done what was anticipated, and that a substantial hazard remains both south and west of Kathmandu, where great earthquakes have ruptured in the past and will do so again in the future. There is an urgent need to keep the public alert and prepared. Earthquakes in India are not restricted to the Himalaya, but also occur further south as the events in Bhuj (2001), Latur (1993) and Jabalpur (1997) showed. These earthquakes give us insights into why India-Asia collision is so asymmetric, with most of the deformation occurring in Asia, and why the geological history of ancient India is so different from that in younger mountain belts. |