Rosalía Jiménez Marilu Alvarado Cristopher Mendoza September 1985, Mexico City
What is an earthquake? • An earthquake is the shaking of the Earth sudden and fast traveling through the the Earth’s crust.
What causes an earthquake? • It is caused by disruption and displacement of ground plates releasing stored energy in the form of seismic waves. • Sometimes the plates are very close or can not move, so energy accumulates between them.
Richter Scale • According to this scale the magnitude of an earthquake is determined from the logarithm of the amplitude of waves recorded by the seismograph.
September 19th of 1985 • On the coasts of Michoacan, almost 400 kilometers from Mexico City, Cocos tectonic plates and North American, slipped violently. • The shock wave took about two minutes to cross the mountains, climb to the plateau and hit the capital. • 7:17-7:19 (Started in Mexico City)
Why Mexico city was the most affected ? Jorge Flores Valdes, emeritus researcher at the Institute of Physics of the National Autonomous University of Mexico (UNAM) "We saw that the seismic response of Mexico City has the characteristics of a Doorway state, which means that there is a state by which energy enters."
Part.2 Explanation According to Flores Valdes, "the seismic waves originating from Acapulco, Michoacan or Guerrero enter the city below, come walking down the rock and suddenly find themselves with this area of mud, which has 90% by volume water, that is, is almost water. " He emphasizes: "They travel seismic waves which are essentially transverse to get here and become longitudinal waves, like sound waves."
Part.3 Results The type mud floor of Mexico City provide a Doorway state that amplifies seismic waves, lengthen its duration and finally determines a frequency of 0.5 Hz constant movement.
Why it is so important? • In two minutes, the great earthquake of 8.1 degrees collapsed a total of 400 buildings and left another thousand ready to be demolished.
Political • The lack of resources to face the emergency and the paralyzation of the city, along with the initial denial of the president De la Madrid of accepting international help increased the damages. Social • The system of collective transportation was affected in 32 stations • The social secure baseball stadium was used to accommodate and recognized bodies. Economical • The damage cause in Mexico City were equivalent to the 10 percent of the GDP of Federal District • 2,831 buildings with structural damages, 880 left in ruins, 370 that could inhabit again with important reparations, and 1,581 with minor reparations. • The damages represent the 2.39% of the country's GDP
How natural components affect the structure of societies? • Most of the buildings that collapsed were construct over what used to be the lake of “ Tenochtitlan”. • In the part of mountains that surrounded the lake, nothing collapsed. • There is a function of trapped wave in the lake that is a resonance
References Anónimo. (S.F.). Terremoto. octubre 21, 2016, de GeoEnciclopedia Sitio web: http://www.geoenciclopedia.com/terremoto/ Aula. (September 19, 2014). El entorno económico de México en el sismo de 1985. Octubre 28,2016, de Dinero en imagen Sitio web: http://www.dineroenimagen.com/2014-09-19/43619 Jorge Castañeda. (September 18, 2015). Terremoto de 1985, la resonancia y la Ecología. Octubre 28, 2016, de Foro Ambiental Sitio web: http://www.foroambiental.com.mx/terremoto-de-1985-la-resonancia-y-la-ecologia/