A magnitude-6.9 earthquake rocked northwestern Mexico’s Gulf of California region early Thursday, the U.S. Geological Survey, or USGS, said.

The temblor occurred at 12:15 a.m. some 134 kilometers (83 miles) northwest of Guerrero Negro, a city in Baja California Sur state.

The earthquake’s epicenter was 162 kilometers (about 100 miles) from La Doce, a city in Sonora state, and 180 kilometers (112 miles) from Santa Rosalia, a city in Baja California Sur.

There are no reports yet of injuries or damage.

On April 2, a magnitude-6.0 earthquake rocked an area between the southern states of Guerrero and Oaxaca.

The temblor was less powerful than the magnitude-7.4 earthquake that occurred on March 20 and was an aftershock, the Mexican Seismology Institute said.

The March 20 temblor, which killed two people, was followed by dozens of aftershocks on the day it occurred.

Mexico, one of the countries with the highest levels of seismic activity in the world, sits on the North American tectonic plate and is surrounded by three other plates in the Pacific: the Rivera microplate, at the mouth of the Gulf of California; the Pacific plate; and the Cocos plate.

That last tectonic plate stretches from Colima state south and has the potential to cause the most damage since it affects Mexico City, which has a population of 20 million and was constructed over what was once Lake Texcoco.

The magnitude-8.1 earthquake that hit Mexico City on Sept. 19, 1985, was the most destructive to ever hit Mexico, killing some 10,000 people, injuring more than 40,000 others and leaving 80,000 people homeless.

The most recent powerful quake to hit Mexico was a magnitude-7.6 temblor that rocked Colima on Jan. 21, 2003.