earthquakes Essay

In Mexico City of 1985 and San Francisco of 1989 there were big earthquakes. Many people died and may buildings were destroyed. About 100,000 people were killed and over 300,000 buildings were destroyed or damaged. Both of these Earthquakes were quite similar.

The 1985 Mexico City earthquake was one of the most devastating earthquakes in the history of the Americas. On Thursday, September 19, 1985, at 7:19 am. local time, Mexico City was struck by an earthquake of magnitude 8.1 on the Richter scale. The epicenter of the earthquake was off the Pacific coast of the Mexican state of Michoacán, a distance of 350 km, in the Cocos Plate subduction zone. It was felt as far away as Los Angeles, California. Many residents of Mexico City dispute the official statistics, and believe that deaths from the quake exceeded 60,000 and more likely approached 100,000.
There was an additional magnitude 7.5 aftershock 36 hours later (the evening of Friday, September 20), which caused widespread panic among the already battered population of the city. A magnitude of 7.5 is enough to destroy buildings within a radius of 150 kilometers. Building damage was worsened by soil liquefaction which causes the loss of foundation support and contributes to dramatic settlement of large buildings. The buildings most damaged were from 6-15 stories in height. The extensive damage was due in part to lax enforcement of building codes and the lack of deep foundations in many Mexico city buildings. Adding to this damage, the water and sewage systems were destroyed, contaminating the city's water supply. Electricity lines were also destroyed and the sparking edges of the wires caused fires. Additionally international communications were severely disrupted due to the collapse of the Central Communications Center of the Ministry of Communications and Transport isolating the city from immediate help and assistance. The quake caused major portions of three of the city's largest hospitals to collapse,...