Most of the buildings in and around Gangtok and adjoining areas devastated by the September 18 earthquake were built on land with a fragile sub-surface, the Geological Survey of India Thursday said.
The GSI submitted a report to the Sikkim government on the earthquake which claimed over 75 lives.
"Most of the damage was to buildings in and around Gangtok and the adjoining areas as the rock below was very fragile," Director, GSI (Sikkim Unit), K Premchand said.
"Another cause was the heavy construction. In future, people should construct less floors and take permission from structural engineers," he said.
According to Premchand, slight tremors would continue for over a month which was natural.
After the earthquake, GSI officials visited all the affected villages to assess damage and collected data from the seismic stations in the state.
The reports have been sent to the Earthquake Geology Division of GSI in Shillong for interpretation, which was awaited, Premchand said, adding the full report would be submitted within this month.
He said he recently visited north Sikkim and saw that there were major damage to mainly to the Mangan-Chungthang, Chungthang-Lachen and Chungthang-Lachung roads, which were littered with landslides triggered by the earthquake.
