Despite Massive Quake Nepal Fault Remains “Nearly Fully Locked”: AIR

Despite Massive Quake Nepal Fault Remains “Nearly Fully Locked”: AIR

The fault that caused the massive Nepalese earthquake on Saturday remains essentially stuck, gathering energy that could cause similar catastrophic events.

“The repeat occurrence of large earthquakes along [Main Himalaya thrust fault zone] (MHT) indicates that the MHT is nearly fully locked,” according to a statement from catastrophe modelling firm AIR Worldwide.

A locked fault is “is not slipping because frictional resistance on the fault is greater than the shear stress across the fault (it is stuck)”, according to a definition from the United States Geological Service (USGS). “Such faults may store strain for extended periods that is eventually released in an earthquake when frictional resistance is overcome.”

AIR explained that the epicenter of Saturday’s event is located in the central section of the MHT, where earlier historic ruptures occurred in 1505 and 1833.

The 2,500 km Main Himalayan thrust fault zone lies on the plate boundary between India and Eurasia plate.

“Since the location of the 1505 and 1833 earthquake are both poorly known, today’s earthquake could represent a repeat of either earthquake,” AIR said. The firm added that the central section of the MHT “is seismically most active fault segment.”

The western section of the MHT, however, has been historically very quiet with only one earthquake in 1905, AIR said. While the fault remains locked, AIR explained, the accumulated energy in the western section of the MHT could generate earthquakes larger than 8.

“The 2005 Kashmir earthquake [which killed 46,000 thousand people] released only a very small portion of the accumulated energy,” AIR said

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