1.+Earthquakes

====Earthquakes happen when the earth's crust slide past each other, releasing massive amounts of energy in the form of seismic waves. These waves, depeding on the intensity of the crust's movement can cause large cities to be destroyed in seconds and the loss of many human lives. Earthquakes usually occur on tectonic plate boundaries because that is where the unstable movement of the earth's crust occurs the most (refer to Figure 2). Often the earthquake occurs with movement over a large area, but there is usually one point where it is most intense. This point is called the focus or hypocentre (refer to figure 2.1).====

=Figure 2= The earthquake locations effectively delineate the plate boundaries. The thickest array of dots running from the tip of Afria, down around India to split above Australia, is called the Mediterranian-Himalayan Belt and the other assortment of black dots down the left of Northern and Southern America (which branches off the right side of the diagram) is known as the Circum-Pacific Belt. These are where earthquakes frequently occur. Cited from **//http://academic.evergreen.edu/g/grossmaz/HAMMVM/index.html//**

=**Figure 2.1**= The most surface damage in an earthquake occurs in the area directly above the focus --> the epicentre. Cited from **//http://visual.merriam-webster.com/earth/geology/earthquake/earthquake.php//**

INTERACTIVE! Construct your own Earthquake --> []

= = =The Scale of An Earthquake. The Modified Mercalli Scale V.S. The Ritcher Scale.= = = -from the National Earthquake Information Center/Magnitude vs Intensity August 30, 2000.
 * Magnitude || Intensity || Description ||
 * 1.0 to 3.0 || I || I) Not felt except by a very few under especially favorable conditions. ||
 * 3.0 to 3.9 || II to III || II) Felt only by a few persons at rest, especially on upper floors of buildings. ||
 * 4.0 to 4.9 || IV to V || IV) Felt indoors by many, outdoors by few during the day. At night, some awakened. Dishes, windows, doors disturbed; walls making cracking sound. Sensation like heavy truck striking building. Standing motor cars rocked noticeably. ||
 * ||  || V) Felt by nearly everyone; many awakened. Some dishes, windows broken. Unstable objects overturned. Pendulum clocks may stop. ||
 * 5.0 to 5.9 || VI to VII || VI) Felt by all, many frightened. Some heavy furniture moved; a few instances of fallen plaster. Damage slight. ||
 * ||  || VII) Damage negligible in buildings of good design and construction; slight to moderate in well-built ordinary structures; considerable damage in poorly built or badly designed structures; some chimneys broken. ||
 * 6.0 to 6.9 || VII to IX || VIII) Damage slight in specially designed structures; considerable damage in ordinary substantial buildings with partial collapse. Damage great in poorly built structures. Fall of chimneys, factory stacks, columns, monuments, walls. Heavy furniture overturned. ||
 * ||  || IX) Damage considerable in specially designed structures, well-designed frame structures thrown out of plumb. Damage great in substantial buildings, with partial collapse. Buildings shifted off foundations. ||
 * 7.0 and Higher || X or Higher || X) Some well-built wooden structure destroyed; most masonry and frame structures destroyed with foundations; Rails bent. ||
 * ||  || XI) Few, if any (masonry) structures remain standing. Bridges destroyed. Rails bent greatly. ||
 * ||  || XII) Damage total. Lines of sight and level are distorted. Objects thrown into the air. ||