This is not scaremongering. Seismologists predict two dangers we have to prepare ourselves for: one is the incomplete tension release after 2015 along faultlines below Kathmandu Valley. This could set off another quake below 8 magnitude in the next decades.
More worrying is the seismic gap in western Nepal where there hasn’t been a mega-earthquake in the last 700 years (see map). Monastic records in Tibet allow us to pinpoint the exact time of the last big earthquake there: 6AM on 1 June 1505. Estimated at 8.9, that earthquake devastated north India, destroyed Agra and other Moghul cities, may have trigged the Annapurna slope collapse that dammed the Seti River unleashing a tsunami when it burst. Pokhara today sits on the debris field of that cataclysmic flood.
Read Also: How prepared are we for the next big one, Sashi Shrestha
Himalayan seismologist Roger Bilham of Colorado University says there is now enough slip deficit beneath western Nepal that can trigger a sudden elastic rebound, moving the terrain southwards and upwards by a shocking 14m in seconds.
An earthquake of 8.5 magnitude epicentred in Surkhet, for instance, would not just destroy much of western Nepal, but also the densely packed cities of the Indo-Gangetic plains. This could conceivably be the greatest loss of life in a natural disaster in human history. The shaking would be intense enough to devastate Kathmandu as well.
As our coverage in this issue points out, it is now time to think beyond reconstruction in the 14 districts affected in 2015 to upgrading preparedness and disaster response in central and western Nepal. Buildings, especially schools and hospitals, need to be urgently retrofitted.
The Gorkha Earthquake three years ago was just a forewarning of an even bigger disaster to come.