Originally registered as a 6.4-magnitude temblor, Mexico’s National Seismology Service (SSN) recalculated the quake’s strength at magnitude 6.0 and at a depth of 8 kilometers.
The quake caused minor damage to buildings in Pacific Coast communities near the epicenter in the town of Pinotepa Nacional in the state of Oaxaca, says Victor Hugo Espindola, seismologist at the SSN.
The earthquake occurred at 2:22 a.m., 120 kilometers from Oaxaca city and 355 kilometers south/southeast of Mexico City, said the US Geological Survey, which calculated the quake at 6.2 magnitude with the epicenter at a depth of 20 kilometers.
In Mexico City, people emptied buildings in the middle of the night in their pajamas. Helicopters circled the city Wednesday morning to survey damage.
“We were a bit scared in the moment, especially the foreigners, because we didn’t know if it would stop,” Mr. Sampedro says. The hotel had been damaged in the devastating 1985 earthquake, which killed at least 9,500 and left more than 100,000 homeless.
Only 10 buildings called for assistance but they did not suffer structural damage, says Elias Miguel Moreno, the capital city’s civil protection minister.
Seismic activity is frequent from the coastal state of Jalisco down to Central America due to movement of the Cocos Plate descending underneath the North American Plate in a process called subduction, Mr. Espindola of the SSN says.
The plate moves 6 centimeters every year, causing small weekly tremors along the belt as well as stronger, magnitude 6 earthquakes and above every two or three years, Espindola says.
Today's earthquake occurred at a shallow depth of less than 5 miles, but strong building construction codes and a slightly weaker magnitude helped prevent the scale of devastation that occurred after recent quakes in Haiti and Chile, Espindola says.
Seven aftershocks of magnitude 4 or less occurred throughout the early morning.
In 1999, a 7.5-magnitude quake was also centered in the Mexican state of Oaxaca, damaging nearly 8,000 homes and killing about 20 people.
In April, northern Mexico, near Mexicali, was struck by a 7.2-magnitude earthquake that also rocked swaths of the American southwest. It was the region's most powerful in decades – more powerful than the one that hit Haiti.