An engineer who works on earthquake risks says the 7.8-magnitude temblor that struck on Saturday may not be the Big One for Nepal.

GeoHazards International's Hari Kumar says: "We were expecting an 8-magnitude to happen along the Himalayas, this is not it."

Kumar is the Southeast Asia regional coordinator for the non-profit group that works on assessing and managing quake risks worldwide.

Immense seismic pressure is still building up along the Nepal-India border, and he says, "The stress which was developing west of this earthquake has not been released."

Nepal's worst recorded earthquake was an 8.0-magnitude temblor in 1934 that all but destroyed the cities of Kathmandu, Bhaktapur and Patan.

Kumar said he hoped Nepal would be able to look beyond the horror and see a chance to rebuild properly. "For Kathmandu, this is their moment of change. I know it is a tragic time, many of their buildings are (fallen) down, but I think this is their time to turn it around."