Question

Identify an earthquake that occurred within the last 6 months and discuss how it is related to plate tectonics (name the plates involved). How could damages or casualties, could have been avoided?

Answer 1

An earthquake occurs when rocks break and slip along a fault in the earth. Energy is released during an earthquake in several forms, including as movement along the fault, as heat, and as seismic waves that radiate out from the "source" in all directions and cause the ground to shake, sometimes hundreds of kilometers away.Most earthquakes occur along the edge of the oceanic and continental plates. The earth's crust (the outer layer of the planet) is made up of several pieces, called plates. The plates under the oceans are called oceanic plates and the rest are continental plates.There are four different types of earthquakes: Tectonic, volcanic, collapse and explosion. A tectonic earthquake is one that occurs when the earth's crust breaks due to geological forces on rocks and adjoining plates that cause physical and chemical changes

For the second time in two weeks, a powerful earthquake struck Mexico, toppling buildings, cracking highways and killing hundreds of people.

The 7.1-magnitude earthquake Tuesday was about 650 kilometers from the epicenter of the 8.1-magnitude earthquake that hit September 8, said Jana Pursley, a geophysicist with the US Geological Survey.

Both earthquakes seem to be a result of the rupture of fault lines within the North American tectonic plate, according to Behzad Fatahi, associate professor of geotechnical and earthquake engineering at the University of Technology Sydney.

"The downtown of Mexico City is notoriously vulnerable to earthquakes because of the very soft and wet ground underneath. Its soil amplifies shaking like Jell-O on a plate, and is prone to liquefaction, which is the ability to transform dirt into a dense liquid when sufficiently churned,

Earthquakes are caused by the slow deformation of the outer, brittle portions of "tectonic plates", the earth's outermost layer of crust and upper mantle. Due to the heating and cooling of the rock below these plates, the resulting convection causes the adjacently overlying plates to move, and, under great stress, deform. The rates of plate movements range from about 2 to 12 centimeters per year. Sometimes, tremendous energy can build up within a single, or between neighbouring plates. If the accumulated stress exceeds the strength of the rocks making up these brittle zones, the rocks can break suddenly, releasing the stored energy as an earthquake.

Most earthquake damage is caused by ground shaking. The magnitude or size (energy release) of an earthquake, distance to the earthquake focus or source, focal depth, type of faulting, and type of material are important factors in determining the amount of ground shaking that might be produced at a particular site. Where there is an extensive history of earthquake activity, these parameters can often be estimated. In general, large earthquakes produce ground motions with large amplitudes and long durations. Large earthquakes also produce strong shaking over much larger areas than do smaller earthquakes. In addition, the amplitude of ground motion decreases with increasing distance from the focus of an earthquake. The frequency content of the shaking also changes with distance. Close to the epicenter, both high (rapid) and low (slow)-frequency motions are present. Farther away, low-frequency motions are dominant, a natural consequence of wave attenuation in rock. The frequency of ground motion is an important factor in determining the severity of damage to structures and which structures are affected.Earthquakes occur all over the world; however, most occur on active faults that define the major tectonic

Fortunately, property damage caused by earthquakes and ensuing fires can be prevented or minimized by following a comprehensive emergency plan before and after an earthquake. Stock up on fire extinguishers and maintain an onsite hose with heavy water pressure

we can prevent earth quake damage by

1. Secure your belongings. The largest financial loss you can incur during an earthquake will be from falling objects and overturned furniture. ...
2. Put latches on cabinet doors and file cabinets. ...
3. Fasten your water heater and other appliances. ...
4. Store hazardous materials in a sturdy place. ...
5. Keep fire extinguishers.