Map: 7.4-Magnitude Earthquake in Indonesia Raises Tsunami Alerts

Note: Map shows the area with a shake intensity of 4 or greater, which U.S.G.S. defines as “light,” though the earthquake may be felt outside the areas shown. All times on the map are Eastern Indonesia time. The New York Times

A major, 7.4-magnitude earthquake struck in Indonesia on Thursday, according to the United States Geological Survey.

The U.S. Pacific Warning Center initially said “hazardous tsunami waves are forecast for some coasts” in the region and that tsunami waves had been observed as a result of the quake. After about two hours and 15 minutes, the center said the danger had passed.

The temblor happened at 7:48 a.m. Eastern Indonesia time about 79 miles northwest of Ternate, Indonesia, data from the U.S.G.S. shows.

As seismologists review available data, they may revise the earthquake’s reported magnitude. Additional information collected about the earthquake may also prompt U.S.G.S. scientists to update the shake-severity map.

Aftershocks in the region

An aftershock is usually a smaller earthquake that follows a larger one in the same general area. Aftershocks are typically minor adjustments along the portion of a fault that slipped at the time of the initial earthquake.

Quakes and aftershocks within 100 miles

Aftershocks can occur days, weeks or even years after the first earthquake. These events can be of equal or larger magnitude to the initial earthquake, and they can continue to affect already damaged locations.

When quakes and aftershocks occurred

Source: United States Geological Survey | Notes: Shaking categories are based on the Modified Mercalli Intensity scale. When aftershock data is available, the corresponding maps and charts include earthquakes within 100 miles and seven days of the initial quake. All times above are Eastern Indonesia time. Shake data is as of Thursday, April 2 at 8:05 a.m. Eastern Indonesia time. Aftershocks data is as of Thursday, April 2 at 1:04 p.m. Eastern Indonesia time.