Abstract. The seismic effects in Nyalam, Gyirong, Tingri and
Dinggye counties along the southern border of Tibet were investigated during
2–8 May 2015, a week after the great Nepal earthquake along the Main
Himalaya Thrust. The intensity was VIII in the region and reached IX at two
towns on the Nepal border, resulting in the destruction of 2700 buildings,
seriously damaging over 40 000 others, while killing 27 people and injuring
856 in this sparsely populated region. The main geologic effects in this
steep rugged region are collapses, landslides, rockfalls, and ground
fissures, many of which are reactivations of older land slips. These did
great damage to the buildings, roads, and bridges in the region. Most of the
effects are along four incised valleys which are controlled by N-trending
rifts and contain rivers that pass through the Himalaya Mountains and flow
into Nepal; at least two of the larger aftershocks occurred along the normal
faults. And, the damage is not related to the faulting of N-trending rifts
but rather is distributed along the intensity of Nepal earthquake. Areas weakened by
the earthquake pose post-seismic hazards. Another main characteristic of
damage is the recurrence of the old landslide and rockfalls. In addition,
there is an increased seismic hazard along active N-trending grabens in
southern Tibet due to the shift in stress resulting from the thrust movement
that caused the Nepal earthquake. NW-trending right-lateral strike-slip
faults also may be susceptible to movement. The results of the findings are
incorporated in some principle recommendations for the repair and
reconstruction after the earthquake.
The stop-start control of seismicity by fault bends along the Main Himalayan Thrust
