Mexico City, Mexico - Two separate, powerful earthquakes rocked Mexico in an eight hour period yesterday.

A strong earthquake struck in the mountains of western Mexico on Wednesday, shaking buildings more than 200 miles away in Mexico City and sending people rushing out of offices onto the streets.

City officials reported no signs of damage after investigative helicopter flights around the city, and Mayor Marcelo Ebrard said that key services in the capital, including its subway system and the international airport, were operating normally.

Authorities in Michoacan state, where the tremor was centered, also had no immediate reports of damage.

The epicenter of the earthquake was 238 miles west-south-west of Mexico City according to the US Geological Survey. The 6.5 magnitude quake struck in the western state of Michoacan at a depth of 12.4 miles and was originally estimated at a strength of magnitude 7.0, but later downgraded.

A quake of that magnitude is capable of producing severe damage in a metropolitan area, but this one occurred in a scantly populated region and emergency services in Michoacan and in the neighboring state of Guerrero, which has been hit by a series of recent quakes, reported no major problems.

Another earthquake, the latest in this series of temblors, struck off the coast of Mexico on Thursday morning only hours after the Michoacan shaker. This one was reported as a 6.9 magnitude and hit the waters between the Baja peninsula and the northern state of Sonora at 12:15 am local time; waking up residents living near the Gulf of California.

This seism was centered 82 miles northeast of Guerrero Negro, and 133 miles west of Hermosillo, and it hit some 6.4 miles below the surface.

According to USGS geophysicist Dale Grant, these events are not aftershocks of the 7.4 magnitude temblor that struck southern Mexico three weeks ago that damaged thousands of homes and killed at least 2 people, although there have been close to 400 aftershocks, including one of magnitude 6.0.

"These are completely separate earthquakes," Grant said, "and there is the potential for more aftershocks."

A quake alert application for Blackberrys that Mexico City's government touted last week did not work. Mexico City Mayor Marcelo Ebrard said the alert system has been working for quakes centered in two southern states and will begin to work for any tremors in Michoacan in the next few days.