MEXICO CITY, Mexico (AFP)— Two people were killed and dozens of buildings were damaged by a powerful 7.7 magnitude earthquake that struck Mexico on the anniversary of two devastating tremors, authorities said Tuesday.

A woman died of injuries caused by a falling wall in Manzanillo in the western state of Colima, civil defense national coordinator Laura Velazquez told reporters.

A man had been killed by falling debris in a shopping centre in the same city due to Monday’s earthquake, which caused buildings to shake and sway in Mexico City.

Nine others were injured across Colima, where more than 150 houses and other buildings were damaged, officials said.

President Andres Manuel Lopez Obrador said it was lucky that the death toll was not higher.

“It was a tremor of considerable intensity,” he said.

The epicenter was located near the Pacific coast, around 400 kilometres (250 miles) west of the capital and 59 kilometres south of Coalcoman in the state of Michoacan, according to seismologists.

The depth was estimated at 15 kilometres.

There were hundreds of aftershocks, the most powerful of which was magnitude 5.8, according to the national seismological agency.

The earthquake struck less than an hour after millions of people in Mexico City participated in emergency drills on the anniversary of two previous disasters.

“It was very scary. I thought: on the 19th again, it can’t be,” said Laura Plaza, a retired teacher.

On September 19, 1985, an 8.1 magnitude quake killed more than 10,000 people and destroyed hundreds of buildings.

On the anniversary of that earthquake in 2017, a 7.1 quake left around 370 people dead, mainly in the capital.

The timing of Monday’s tremor was no more than a coincidence, the national seismological agency said.

“There is no scientific reason to explain it,” it added.

Mexico sits in the world’s most seismically and volcanically active zone, known as the Ring of Fire, where the Pacific plate meets surrounding tectonic plates.

Mexico City, which together with surrounding urban areas is home to more than 20 million people, is built in a natural basin filled with the sediment of a former lake, making it particularly vulnerable to earthquakes.

The capital has an early warning alarm system using seismic monitors that aims to give residents enough time to evacuate buildings when earthquakes hit seismic zones near the Pacific Coast.