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In general, natural hazards losses are measured in dollars in developed nations and lives in developing ones. But you're right, a 7.9 is huge. Even under southern California it would be devastating (see [1] for an idea based on the 1857 Fort Tejon quake). Nepal has had a lot of aid from Western nations to build more earthquake-resistant structures. But a big part of the problem isn't the structures themselves, it's the location of the building (the slope, substrate, and so forth). The options for ideal locations in much of Nepal are very limited because of the terrain. People also live where they do because they have for thousands of years, vs. the US where population densities are lower and we have built our cities more recently, looking for areas that suit modern techniques. North/central Europe doesn't have the exposure to earthquakes but Italy has problems with this; see L'Aquila for an example of the damage caused by very moderate seismicity. The most recent analogous earthquake to this would be the 2008 Wenchuan, China earthquake: It was a very similar-sized earthquake, of somewhat similar type (it was reverse and strike-slip, while this is a thrust earthquake), and it occurred on a continental fault at similar depth, rather than a subduction zone where most of the shaking is offshore. It was a real killer, and a lot of the damage was caused by landsliding rather than actual ground shaking [2]. I fear this could be a big problem here. The Himalaya are eroding very rapidly, and are very prone to landslides anyways. I am not sure about the effects of mountain agriculture but I would assume that the clearing, irrigation and terracing that is necessary for the Nepalese to live in the mountains makes the hazards worse by stripping the plant roots and saturating the soil with water (wet soil/rock is more prone to landslides). The Himalaya (esp. Bhutan[3]) also has a lot of lakes where glacial sediments have dammed creeks very high up in the mountains, and a huge concern is the failure of the dams during even moderate seismicity; this could cause huge, scouring floods to rip through villages. I think the upside of this is that it is 'only' a Mw 7.9. Many of us in the active tectonics community have been very worries about the possibility of an 8.5-9 earthquake on the Main Himalayan Thrust; there is some evidence for this in the past, based on the length and size of old earthquake scarps at the Himalayan rangefront, and by analogy to other convergent plate margins. It is much, much better if the accumulated seismic energy is released in smaller amounts like more frequent 7.9s than a less frequent 9 (an earthquake of this size would basically rupture the Himalayan front from Assam to Dehradun). [1]: http://earthquake.usgs.gov/earthquakes/shakemap/sc/shake/185...
[2]: http://landslides.usgs.gov/learn/photos/international/landsl...
[3]: http://www.nlcap.net/fileadmin/NCAP/Resources/Bhutan_present... |