"The waves were like riding on the ocean after the initial shock subsided," Ian Pierce, one of a team of researchers from the University of Nevada, Reno's Nevada Seismological Laboratory studying the Himalayan earthquake fault, said about the 7.3 aftershock that struck Nepal and India Tuesday, May 12.
The team is safe in Kathmandu following the strong aftershock that caused additional loss of life and destruction in the region where disaster struck two weeks ago with a magnitude 7.8 earthquake. They spent the day south of Kathmandu towards India in the immediate aftershock zone where they continue their study of the hundreds-of-miles long Himalayan fault.
They are documenting their progress in daily updates, when internet connections are possible, on the University's College of Science website. The team, director of the University's Center for Neotectonic Studies and College of Science geoscientist Steve Wesnousky and his two doctoral students Steve Angster and Ian Pierce, have been there about a week. Wesnousky left Nepal by plane just before the aftershock.
One of the first scientists to enter Nepal following the April 25 Gorkha earthquake, Wesnousky has been on the ground in the Himalayas searching for geophysical signs of the magnitude 7.8 earthquake.
"Just before it hit, I heard a commotion from nearby dogs and goats, and then we were moving," Angster wrote on his website. "Scary feeling, but we all felt relatively safe where we were standing. We saw seiche (water splashing and swaying) in ponds, bricks falling off of chimneys that we were measuring, and dust billowing up from collapsed structures on the horizon. Shaking felt long and slow, kinda like being on a boat in rough water, but not seeing the boat sway. "
"It was difficult to stand during the first few seconds," Pierce said. "Shaking like a boat lasted several minutes, likely waves bouncing around the valley. Intense shaking maybe 20 or 30 seconds, but we weren't counting."
Tomorrow the pair will head to Pokerah as a jump off point to get to Gorkha where the main shock was two weeks ago.
"Our prayers and thoughts go out to Nepalese people tonight," Angster said. "Saw lots of people camping out in open spaces tonight. There are so few open spaces that we even saw people in medians in between busy streets."
The aftershock hit near the town of Namche Bazar, near Mount Everest. The U.S. Geological Survey reported it as magnitude 7.3. The April 25 earthquake centered in western Nepal was magnitude 7.8, four times stronger than today's aftershock. It was felt as far away as Delhi, the capital of India, and Dhaka, the capital of Bangladesh. Strong tremors were felt in the capital of Nepal, Kathmandu, which was badly damaged in last month's earthquake.
What the team finds may help scientists to calibrate results from earlier studies and to quantify what the potential is for additional earthquakes in the magnitude 8 or magnitude 9 range. The team plans to be there for two weeks, possibly longer if they are successful in finding ground ruptures.