Earthquake and its Effect in Environment.pptx

EARTHQUAKE

1. EARTHQUAKE

2. Earthquakes are the result of sudden movement along faults within the Earth. The movement releases stored-up ‘elastic strain’ energy in the form of seismic waves, which propagate through the Earth and cause the ground surface to shake. Such movement on the faults is generally a response to long-term deformation and the buildup of stress. Earthquake

3. WHAT CAUSES AN EARTHQUAKE?

4. Seismic waves from large earthquakes pass throughout the Earth. These waves contain vital information about the internal structure of the Earth. As seismic waves pass through the Earth, they are refracted, or bent, like rays of light bend when they pass through a glass prism. Because the speed of the seismic waves depends on density, we can use the travel time of seismic waves to map change in density with depth and show that the Earth is composed of several layers. The structure of the Earth

5. The Earth’s outermost layer is fragmented into about 15 major slabs called tectonic plates. These slabs form the lithosphere, which is comprised of the crust (continental and oceanic) and the upper part of the mantle. Tectonic plates move very slowly relative to each other, typically a few centimeters per year, but this still causes a huge amount of deformation at the plate boundaries, which in turn results in earthquakes. Plate tectonics

6. What drives the movement of tectonic plates? Three of the forces that have been proposed as the main drivers of tectonic plate movement are: mantle convection currents: warm mantle currents drive and carry plates of lithosphere along a like a conveyor belt ridge push (buoyant upwelling mantle at mid-ocean ridges): newly formed plates at oceanic ridges are warm, so they have a higher elevation at the oceanic ridge than the colder, more dense plate material further away; gravity causes the higher plate at the ridge to push away the lithosphere that lies further from the ridge slab pull: older, colder plates sink at subduction zones because, as they cool, they become more dense than the underlying mantle and the cooler, sinking plate pulls the rest of the warmer plate along behind it

7. https://www.bgs.ac.uk/discovering-geology/earth-hazards/earthquakes/what-causes-earthquakes/ Reference