The extent of likely earthquake disasters in the Himalaya and how to reduce them

We estimated the likely numbers of fatalities and injured for 5 line source earthquake scenarios in the Himalaya with 7.6 ≤ M ≤ 8.7. Our confidence in the results is based on verifications for 5 historic Himalayan earthquakes for which the location, M, the isoseismal lines, and the numbers of fatalities are known. The magnitudes of these test earthquakes were 6.6 ≤ M ≤ 7.8. We estimate that the numbers of strongly affected people (affected by intensities I ≥ VI) may number 12 to 78 million. The numbers of fatalities is the most tractable parameter for the extent of an earthquake disaster. We estimate that in our scenarios the number of fatalities will range from 100,000 to 600,000, the numbers of injured 400,000 to 1,000,000. Based on the analysis of 53 earthquakes with 6.3 ≤ M ≤ 8.0, including earthquakes in the Himalaya, more than 90% of casualties will be in the rural population. To concentrate efforts of strengthening buildings in urban agglomerations is therefore not the most useful concept. Instead, the rural population should be helped to install low cost earthquake protection units in dwellings, such as Earthquake Closets (EC, similar to tornado shelters), protective structures over beds, or similar low cost devices. ECs, for example, could be reached within 5 sec to 10 sec, the S-P-time before the strongest shaking. The increased probability of survival in an EC or protected bed is 1,000 to 10,000 fold. Estimating that 25% of the casualties would be saved by ECs or other protective units, one concludes that 25,000 to 150,000 fatalities and 100,000 to 250,000 injuries could be avoided in assumed great earthquakes. Children's lives could be saved if extra strong benches would replace flimsy desks in schools. In addition, the locations, sizes and construction type of critical facilities are poorly known in the Himalaya. An analysis of schools shows that in the Himalaya only about 5% to 10% of schools are mapped in the OpenStreetMap (OSM). We assume that the same is true for health facilities. It seems therefore urgent to launch a campaign involving local people, including students, in mapping hospitals and schools for the OSM. Knowing their locations and conditions would be of immeasurable value to first responders and to retrofitters. This training goes along with fostering awareness regarding all aspects of earthquakes in the population.