May 13, 2015
The latest earthquake which shook Nepal yesterday at 12:52 pm was large enough – 7.3 – to trigger its own sequence of aftershocks as stress redistributes around the ruptured fault line.
It is part of the same fault system as the April 25 earthquake.
When a fault ruptures during an earthquake, the stress along the portion of the fault that slipped is relieved while the stress at the locked ends increases. Located between Kathmandu and Mount Everest, yesterday’s event and its aftershocks are far enough east of the older earthquakes that it appears a critical stress threshold was exceeded and the adjacent segment of the fault system ruptured. While unfortunate, this is not uncommon.
Cumulative damage is absolutely a problem with this latest earthquake. The intense shaking was a trigger to set off another round of landslides in the dramatically steep terrain, further complicating transportation within the region. It was also enough to collapse already-damaged buildings, although thankfully the causalities from this latest disaster should be lower with people already evacuated from the previous earthquakes.
The upcoming monsoon season will no doubt increase the possibility of landslides.
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