What We Know About the Earthquake in Myanmar

A 7.7-magnitude earthquake struck central Myanmar on Friday, sending shock waves across a vast expanse of Southeast Asia and causing deaths and damage hundreds of miles away from the epicenter.

The earthquake shook buildings in neighboring Thailand and China, and rattled bridges and homes as far away as Vietnam. At least 23 people have died, and the death toll is expected to rise, especially in Myanmar, where the injured are arriving at hospitals in the country’s second-largest city, Mandalay.

Where was the epicenter?

The quake struck near Mandalay, in central Myanmar, at roughly 12:50 p.m. local time, according to the U.S. Geological Survey. Approximately 12 minutes later, an aftershock with a magnitude of 6.4 hit the same area.

An earthquake with a magnitude of 7.7 is considered major, and the magnitude of the aftershock is categorized as strong and likely to cause damage, particularly in densely populated areas, according to the agency.

Central Myanmar, where large plates of the Earth’s crust are in motion, is particularly prone to powerful earthquakes. The country lies on the eastern end of the Alpide Belt, one world’s most active zones of seismic activity. Three quakes of magnitude 7.7 or greater have struck in or near Myanmar in the last century, according to a U.S.G.S. database, with the most recent in 1988.

The earthquake on Friday struck at a relatively shallow depth of six miles, meaning it was likely to cause more violent shaking. That shaking was felt as far away as Thailand’s capital, Bangkok, more than 800 miles away from the epicenter.

Which countries have been affected?

Despite the limited information from the authorities in Myanmar, the earthquake was almost certainly most detrimental to the country, the second-largest by landmass in Southeast Asia. The epicenter of the quake occurred in central Myanmar, outside Mandalay, a city with an estimated population of 1.5 million people.

Neighboring Thailand also felt the might of the earthquake, particularly in Bangkok, where around 11 million people live in the metropolitan area. Prime Minister Paetongtarn Shinawatra declared the city an “area of emergency,” asking residents to evacuate from tall buildings to avoid aftershocks.

In China, news media outlets in Yunnan Province, neighboring Myanmar, reported damage to buildings in the busy border city of Ruili.

The shaking was also felt in Bangladesh, to Myanmar’s west, but there were no immediate reports of damage.

What is the death toll, and what damage has been caused?

The death toll is expected to rise as rescue workers dig through the rubble, as are the numbers of injured people making their way to hospitals. In Myanmar, at least 20 people were reported dead, and another 300 were injured, according to a doctor at the Mandalay General Hospital.

Images of the extent of the damage in Mandalay showed that the Ava Bridge, originally built by the British in the 1930s, had partly collapsed, according to footage verified by The New York Times. But heavy censorship enforced by Myanmar’s military government has made it hard to see the full picture of the damage.

In Thailand, three people died when a skyscraper that had been under construction collapsed in Bangkok. More people, probably construction workers, remained stuck under the rubble, according to the authorities. The city’s elevated train service was shut down and people fled from tall buildings after the city was placed in a state of emergency.

Chinese state media reported that an unspecified number of people were injured, with houses and buildings damaged in the city of Ruili.

Reporting was contributed by Sui-Lee Wee, John Yoon, Keith Bradsher, John Keefe, Richard C. Paddock, Muktita Suhartono, Adam Satariano and Paul Mozur.