At least 58 people have died in the most powerful earthquake to hit Mexico in more than eight decades.
- The quake is Mexico's strongest since 1932
- Waves rose as high as 0.7 metres, but a tsunami threat has passed
- Authorities say there have been dozens of aftershocks and more are likely
The magnitude-8.1 quake off Mexico's southern coast late Thursday (local time) was stronger than a devastating 1985 quake that flattened swathes of Mexico City and killed thousands.
This time damage to the city was limited, as the quake was deeper and further from the capital.
The southern town of Juchitan in Oaxaca state, near the epicentre, was hit particularly hard, with sections of the town hall and other buildings reduced to rubble.
"The situation is Juchitan is critical, this is the most terrible moment in its history," mayor Gloria Sanchez said.
The head of Mexico's civil defence agency Luis Felipe Puente said 45 people had been confirmed dead in the southern state of Oaxaca, where the quake hit the hardest.
Another 10 people died in Chiapas and three more in the Gulf coast state of Tabasco, he said.
'There are so many bodies'
People ran into the streets in Mexico City as the quake struck.
"It almost knocked me over," Gildardo Arenas Rios, a 64-year-old security guard in Mexico City's Juarez neighbourhood, said.
In Juchitan, shocked residents stepped through the rubble of dozens of collapsed buildings.
"Look at what it did to my house," Maria Magdalena Lopez said, in tears outside its shattered walls. "It was horrifying, it fell down."
Alma Rosa, sitting in vigil with a relative by the body of a loved one draped in a red shroud, said: "We went to buy a coffin, but there aren't any because there are so many bodies."
Waves rose as high as 0.7 metres in Mexico, the Pacific Tsunami Warning Centre said, though that threat passed.
The US Geological Survey (USGS) said the quake's epicentre was in the Pacific, 87 kilometres southwest of the town of Pijijiapan at a depth of 69 kilometres.
John Bellini, a geophysicist at the USGS National Earthquake Information Centre in Golden, Colorado, said Thursday's quake was the strongest in Mexico since a magnitude-8.1 quake struck the western state of Jalisco in 1932.
Across the Pacific, the national disaster agency of the Philippines put the country's eastern seaboard on alert for possible tsunamis, although no evacuations were ordered.
More aftershocks likely
Rescue workers searched through the night for anyone trapped in collapsed buildings, but by early on Friday the toll appeared to be less severe than that seen in many far less powerful tremors.
Windows were shattered at Mexico City airport and power went out in several neighbourhoods of the capital, affecting more than 1 million people.
The 1985 earthquake was by the coast, about 322 kilometres from Mexico City.
Thursday's quake was 756 kilometres from the city.
Authorities reported dozens of aftershocks, and President Pena Nieto said the quake was felt by around 50 million of Mexico's roughly 120 million population, with further aftershocks likely.
He advised people to check their homes and offices for damage and gas leaks.