EARTHQUAKES AND THERE ENVIRONMENTAL EFFECTS

Earthquakes and there Environmental Effects

Earthquakes and there Environmental Effects

Q1- Earthquakes and there Tectonic Setting

The process of tectonic loading due to relative plate motion can be rationally modelled by considering viscoelastic stress relaxation in the asthenosphere and realistic frictional properties of the fault. The fundamental cause of tectonic loading is the increase of slip decit in high-strength seismogenic regions on a plate boundary. In the stress accumulation and release process of a complex fault system, interaction between adjacent seismic faults is essential. Earthquakes are naturally occurring geologic phenomena resulting from the cooling of the earth and the consequent release of energy from it interior. Although some earthquakes result from the settling of earths mass and can occur almost anywhere on the surface of Earth, most are due to the movement and interaction of tectonic plates and therefore tend to occur at or near plate boundaries. The purpose of this lab is three-fold.

2) Earthquake hazards to humans and their activities include discussion of- (why do people live in tectonically active regions, - the geological processes associated with each identified hazard, -Risks to humans

Ans. Earthquakes are vibrations or tremors that occur in the Earth as a result of rocks suddenly moving against each other. The epicentre of an earthquake is the point on the Earth's surface that is directly above where the movement occurred. The focus of an earthquake is the exact position of the earthquake. The precise location of an earthquake can be described by stating the map coordinates for the epicentre and a depth for the focus.

The Australian continent lies entirely within the Australia-India plate, and so it does not experience plate boundary processes. Plate margin earthquakes account for ninety percent of all earthquakes and are the result of the constant movement of the rocks at plate boundaries against each other. (Scheirer, D.S., Page, W.R., and Miller, J.J., 2006, Pp. 116-118.)

Intra-plate earthquakes are those that occasionally occur in the crust of plates and away from the more active plate boundaries. The causes of intra plate earthquakes are not well understood, but they are usually caused by compressive stress in rocks.

Australia has three distinct regions of earthquake activity. These are:

the Eastern region, covering the eastern highlands and coastal areas the Central region, extending from near Adelaide to the Simpson Desert the Western region, encompassing several distinct zones. In the central seismic region of Australia, earthquakes have been associated with a 120 kilometre long fault as a result of north-south compressive forces. (D. S. Brumbaugh, 1998 Pp. 180-183)

The stress causing intra-plate earthquakes may be associated with isostasy, which is the tendency for rock masses to rise or sink to achieve a balance between downward weight forces and upward buoyancy forces. Erosion and deposition change historically balanced isostatic forces, causing new regions of stress and strain.

Some intra-plate earthquakes may be related to the stress at plate boundaries and to temperature changes in the lithosphere caused by processes in the ...