KUMAMOTO, Japan, April 16 (UPI) -- Troops have been deployed to southern Japan after three powerful tremors rocked the region in as many days, leaving a total of an estimated 32 dead.
A major tremor rocked southern Japan on early Saturday in the same region where a quake hit late Thursday, leaving up to 10 dead, according to some reports. Seismologists now believe Thursday's quake, magnitude-6.5, was a "foreshock" leading up to the first of Saturday's two tremors, which had a magnitude of 7.4 on the Richter scale. That quake struck overnight. Hours later, a third tremor measuring 5.3 struck, which seismologists consider an aftershock.
Seismologists said up to 165 smaller aftershocks have hit Kumamoto prefecture, CNN reported.
Authorities ordered 20,000 troops to the region to help local firefighters and police in search and rescue efforts. They reportedly arrived Saturday morning.
Some victims of the quakes are believed still trapped under rubble or buried alive. Rescue efforts are being hampered by heavy rain in the region, which has already experienced significant mudslides as a result of the seismic activity.
A tsunami warning was initially issued after the quake, but later lifted.
The quake caused heavy damage on Kyushu island, where nearly 200,000 homes lost electricity. Japan's Chief Cabinet Secretary Yoshihide Suga said the damage caused by the earthquake was substantial.
At least 92,000 residents in and around Kumamoto have been displaced, BBC said. The Kumamoto government has opened some 100 evacuation shelters and has begun handing out food and blankets to residents.
Suga said more than 50 people remained trapped and nearly two dozen buried alive, ABC News reported. Nearly 500 were injured -- 44 of whom are critically hurt.
ABC's report also said fires and a landslide followed Saturday's earthquake. Rescuers are searching for survivors in buildings that have sustained catastrophic damage.
"No question, this is a large and very important earthquake," Doug Given, a geophysicist with the USGS, said. "And it will do a lot of damage."
As day broke Saturday morning, authorities got a better look at the extensive damage the quakes caused. The earthquake happened around 1:30 a.m. local time -- a little more than 24 hours after Thursday's 6.5 magnitude quake.
Seismic activity is commonplace in Japan and much of the Asian Pacific Rim, which is positioned on the so-called geologic "Ring of Fire," where subterranean tectonic plates converge.
Doug G. Ware contributed to this report.