1985 Mexico City Earthquake

The 1985 Mexico City earthquake was an earthquake that shook Mexico City on 19 September 1985. The country severed devastating casualties, as well as serious damage to the capital city. The earthquake struck at 7:19 local time. It measured 8.1 on the Richter Scale, and surrounding Mexican States such as Jalisco, Guerrero, and Michoacán were also affected, but the damage was only mild to moderate. Most of the damage was concentrated in a 25 km2 area of Mexico City, 350 km from the epicentre. The damage cost three to four billion USD.

The earthquakes epicentre is located in the Pacific Ocean, off the coast of Michoacán, some 350km away from Mexico City. It lies in the Cocos Plate subduction zone, in the Michoacán Seismic Gap, a section of the fault line. The Cocos Plate pushes against and slides under the North American Plate, creating a convergent plate boundary (see diagram below). This caused many natural disasters, including 42 magnitude 7.0 earthquakes or the 1,985 Mexico City earthquake. The earthquake was felt as far as Los Angeles and Houston, over 825 000 square kilometres during the main event (its energy equivalent to approximately 1 114 20-kiloton atomic bombs).

Mexico suffered bad consequences after the earthquake: 10,000 dead (some sources state that the death toll may reach up to around 30,000), 30,000 injured, 250,000 homeless and 200,000 jobless. Around 5,000 bodies were recovered from the debris. Of the remaining survivors, about 40% of the people were left without electricity and around 70% were left without telephone service. Cuauhtémoc, which includes a historic downtown, suffered the most damage of the entire city. Water drainage and pipes broke in 163 places, which resulted in having water supply either cut off or contaminated. 137 schools collapsed and 1,687 of them were damaged. In addition, over 800 buildings were damaged, including offices, schools and hospitals and a communications tower. Mexico City had no communications with the outside world for many days. When the damage was finally assessed, 3,000 buildings in Mexico City were demolished and another 100,000 suffered serious damage. The property damage mounted up to 5 million USD.

One preparation that was been made for future disasters was an alarm system, Sistema de Alerta Sísmica (SAS), which sends early-warning messages electronically from sensors along the coastal subduction zone in Guerrero. An alarm is supposed to go off if an earthquake of over magnitude 6.0 Is detected.

Bibliography

Wikipedia

http://en.wikipedia.org/wiki/1985_Mexico_City_Earthquake

BBC on This Day

http://news.bbc.co.uk/onthisday/hi/dates/stories/september/19/newsid_4252000/4252078.stm

This Day in History

http://www.history.com/this-day-in-history.do?action=Article&id=50842

CSI: Pompeii

Mount Vesuvius was believed to be a sleeping volcano. Nobody ever knew or heard of a volcano before. When it erupted at 79CE at around 1pm, the people of Pompeii thought that the gods have decided to erase them from the face of the world.

During the reign of Emperor Vespasian, Pompeii was a prosperous city, with public shows gladiatorial fights, streets buzzing with all types of people with different status: Patricians, plebeians, slaves or prisoners. Gladiators roamed the streets as public heroes; love notes left by female fans can be seen almost everywhere. All was pleasant until 10am, when the ground started to tremble slightly. The Romans, however, ignored it, and continued their daily chores. Little did they know of the disaster that was to follow. The earth tremors started to become more obvious, and the inhabitants of the city still ignored what was happening. Then, at 1pm, Mount Vesuvius erupts, spilling ashes everywhere, falling on roofs of the houses in the city. The ashes were becoming larger and larger as more of them rained down. People ran into their houses, seeking shelter – anywhere that could cover them from the horror coming from the once silent mountain. All those who stayed in the streets had their heads smashed open by stones of pumice that fell upon the city. Jupiter had decided to punish them all for all their bad deeds. Patricians hurried to their shrines, begging for mercy from the god of the sky and thunder. Very soon after the eruption, the Roman roofs, which were only built to withstand nothing more than rain, collapsed under the unbearable weight of the ash and pumice, crushing those it housed. A huge dark cloud swept over Pompeii like a blanket, trapping its inhabitants in darkness. Pliny the Elder, who was stationed at Misenum during the eruption, witnessed the eruption. He was an admiral of the Roman Navy and also a naturalist, and claims that the eruption is nothing more than a work of nature. Then, hot ash and lava came out of the volcano and swept into the streets of Pompeii, burning pedestrians and turning them into charcoal. Eyes burnt, skin cells and other soft tissues evaporated and brains exploded in the process. People of other cities near Mount Vesuvius either met the same fate or suffocated when the ash and smoke filled their lungs.