4th earthquake strikes Indonesia

JAKARTA, Indonesia (CNN) -- An earthquake with a preliminary magnitude of 6.2 struck northeast of Sulawesi, Indonesia, Thursday afternoon, a day after three major earthquakes struck the region, according to the U.S. Geological Survey.

The quake struck underwater at a depth of about 20 kilometers (13 miles) about 300 km northeast of Bitung at 5:48 a.m. ET. The area is 2445 km northeast of Jakarta.

The National Oceanic and Atmospheric Administration's Pacific Tsunami Warning Center did not issue a tsunami threat following the earthquake.

"Based on all available data a destructive Pacific-wide tsunami is not expected," a NOAA statement said.

In the past 24 hours the region has been rocked by heavy seismic activity -- with a total of at least 60 tremors rattling the country, according to Indonesia's Social Welfare Minister Aburizal Bakrie.

The seismic shakedown began Wednesday night with a deadly 8.4-magnitude quake -- centered in southern Sumatra, which is west northwest of Jakarta.

A 7.8-magnitude earthquake struck Thursday morning at about 6:45 a.m. (7:45 p.m. Wednesday ET), USGS said. The epicenter was about 185 km south-southeast of Padang and about 200 km northwest of Bengkulu.

About four hours later, the USGS reported that a 7.1-magnitude quake had rocked the region. Sandwiched in-between were half a dozen temblors measuring 5.0 and above.

It was not immediately known whether Thursday's quakes were aftershocks of Wednesday's event.

At least 10 aftershocks of magnitude 5.1 to 6.0 were felt in the region after the larger quake, which shook buildings hundreds of miles away, killed at least nine people and generated a small tsunami about 60 cm high along the Sumatran coast.

"Our main concern is the people," Bakrie said from Padang. "The victims are not as dire as we thought and everything has been taken care of."

People in the Indian Ocean region have been extremely skittish about the possibility of earthquake-induced tsunamis since December 2004, when gigantic waves triggered by a 9.1-magnitude quake that killed more than 200,000 people in seven countries.

Wednesday evening's quake killed at least nine people in Bengkulu province and Padang, and an unknown number were injured or missing, according to officials. Search-and-rescue operations, suspended overnight, resumed at daylight Thursday, which also marked the start of the holy month of Ramadan in the mostly Muslim country.

The relatively light loss of life can be attributed to national and provincial governments being battle-tested by a string of powerful earthquakes over the last three years, Bakrie said.

"The people understand more about the problems and the danger of the earthquakes," according to Bakrie. "The central government as well as the district government, at the provincial level, has warned the people ... so the system works."

The powerful quake shook buildings about 385 miles away in the Indonesian capital, Jakarta, and also in Singapore, about 435 miles from the epicenter.

"Doors started to creak, and the whole apartment seemed to ... make a cracking noise," said Rahayu Saraswati, who lives on the 35th floor of a building in Jakarta. "We ran out to the emergency staircase with other residents of the floor and ran all the way down to the lobby."

Bakrie said thousands of homes have been damaged in Sumatra.

Indonesia, a chain of islands in a seismically active area, is highly prone to earthquakes. Since the devastating tsunami of December 2004, Indonesia has fallen victim to 15 earthquakes with magnitudes of 6.3 or higher, according to the USGS. The quakes have killed almost 8,000 people, with the bulk of the deaths coming last summer.

The deadliest quake last summer came on May 26, 2006, when a magnitude-6.3 quake 16 km south-southeast of Yogyakarta left 5,749 dead. On July 17, 2006, a magnitude-7.7 temblor hit 145 miles south-southwest of Tasikmalaya, in Indonesia's Java region. The quake killed 730 people.

Another devastating quake on March 28, 2005 -- a magnitude-8.7 about 201 km west-northwest of Sibolga -- killed 1,313 people. E-mail to a friend

CNN's Andy Saputra contributed to this report.

All About Sumatra • Pacific Tsunami Warning Center • Indonesia