The 1985 Mexico City earthquake, a severe earthquake that occurred on September 19, 1985, off the coast of the Mexican state of Michoacán, caused widespread death and injuries and catastrophic damage in Mexico City’s capital. The magnitude-8.0 quake occurred at 7:18 a.m.
The magnitude-8.0 quake occurred at 7:18 am. Many sources place the location of the epicenter in the state of Michoacán—approximately 200 miles (320 km) from Mexico City—in a region of tectonic tension between the North American Plate and the subducting Cocos Plate. Some accounts, however, place the epicenter just off the coast of Michoacán in the Pacific Ocean.
The expanse of the subduction zone along which the quake occurred was part of the Middle America Trench, the eastern boundary of the tectonically volatile Circum-Pacific Belt. That expanse was known as the Michoacán seismic gap because seismic energy had accumulated there since a 1911 earthquake; temblors had occurred on either side during the 1970s. A nearly equal magnitude second tremor occurred the following evening southeast of the first quake.
Although some damage occurred in Michoacán and surrounding regions—including the state of Jalisco, where nearly 600 adobe houses were reduced to rubble in Ciudad Guzmán—the destruction was concentrated in Mexico City as a result of the unique topography upon which the capital is situated. The central city, constructed on the dry bed of the drained Lake Texcoco, endured the heaviest shaking because loose lacustrine sediments amplified the shock waves. The ground motion in this area measured five times that in the outlying districts, which had different soil foundations. Buildings of 5 to 15 stories were most affected, as their interaction with the shock waves created a harmonic resonance, exacerbating the degree of swaying. More than 400 buildings collapsed, and thousands more were damaged.
The chaos in Mexico City was compounded by the loss of electricity, leaving the capital without public transit or working traffic lights. Though power was restored the day after the first quake, the tremor that evening knocked it out again. Damage to the telephone system rendered the city incommunicado for several days.
Furthermore, Mexican Pres. Miguel de la Madrid and his advisers refused to fully deploy the national emergency plan. Some observers interpreted this inaction as a maneuver designed to prevent the military from appreciating political cachet by coordinating the rescue operations. De la Madrid declined early offers of international assistance as well but quickly reversed course, accepting supplies and money from a range of countries coordinated by the United Nations.
A second quake struck Central Mexico with 7.1 magnitude force on September 19, 2017, the anniversary of a devastating earthquake in 1985 that had left 10,000 people dead.
On September 7, 2017, an 8.1-magnitude earthquake jolted Mexico, claiming at least 98 lives. It was the strongest to strike there in a century. Just days later, a 7.1-magnitude earthquake shook Mexico City on September 19, 2017, toppling structures and prompting evacuations across Mexico’s capital.
220 were killed in Mexico City, 74 in the state of Morelos, 45 in Puebla, 15 in Mexico State, six in Guerrero, and one in Oaxaca.
Reactions to the third major earthquake to hit Mexico in 40 years on September 19,
“No way!” and “Ah shit, here we go again …” were among the reactions on social media to Monday’s powerful earthquake, the third in fewer than 40 years to afflict Mexico on September 19.
Hopefully, this year we will not have an earthquake on this date…
San Miguel Times
Newsroom
