Earthquakes

Views:
 
     
 

Presentation Description

No description available.

Comments

Presentation Transcript

Slide 1: 

Causes Safety Measures Rishabh K.V. Ganeshkhind, Pune

Earthquake : 

Earthquake An earthquake is the result of a sudden release of energy in the Earth's crust that creates seismic waves. Earthquakes are recorded with a seismograph. The moment magnitude (or the related and mostly obsolete Richter magnitude) of an earthquake is conventionally reported, with magnitude 3 or lower earthquakes being mostly unrecognizable and magnitude 7 causing serious damage over large areas.

How does an Earthquake occur? : 

How does an Earthquake occur? Tectonic earthquakes will occur anywhere within the earth where there is sufficient stored elastic strain energy to drive fracture propagation along a fault plane. In the case of transform or convergent type plate boundaries, which form the largest fault surfaces on earth, they will move past each other smoothly and only if there are no irregularities along the boundary that increase the frictional resistance. Most boundaries do have such asperities and this leads to a form of stick-slip behavior. Once the boundary has locked, continued relative motion between the plates leads to increasing stress and therefore, stored strain energy in the volume around the fault surface. This continues until the stress has risen sufficiently to break through the asperity, suddenly allowing sliding over the locked portion of the fault, releasing the stored energy. This energy is released as a combination of radiated seismic waves, frictional heating of the fault surface, and cracking of the rock, thus causing an earthquake.

Seismograph : 

Seismograph Seismographs are instruments that measure and record motions of the ground, including those of seismic waves generated by earthquakes, nuclear explosions, and other seismic sources. Records of seismic waves allow seismologists to map the interior of the Earth, and locate and measure the size of these different sources.

Tectonic Plates : 

Tectonic Plates

Faults : 

Faults There are three main types of fault that may cause an earthquake: normal, reverse (thrust) and strike-slip. Normal and reverse faulting are examples of dip-slip, where the displacement along the fault is in the direction of dip and movement on them involves a vertical component. Normal faults occur mainly in areas where the crust is being extended such as a divergent boundary. Reverse faults occur in areas where the crust is being shortened such as at a convergent boundary. Strike-slip faults are steep structures where the two sides of the fault slip horizontally past each other ; transform boundaries are a particular type of strike-slip fault. Many earthquakes are caused by movement on faults that have components of both dip-slip and strike-slip; this is known as oblique slip.

Safety Measures : 

Safety Measures Planning for an earthquake: Identify safe spots and places in each room. Have a first-aid box which can be accessible in case of an earthquake. Fix tall heavy furniture like a cupboard to a wall firmly. Keep electrical appliance that use breakable substance like TV in a stable place. Keep glass objects on lower ground. Keep away flammable substances. If an earthquake occurs: Take cover below wooden desks and tables. Keep away from windows Lie down on the floor and cover your head with your hands. Try to exit your apartment and go outside to a road. Contact emergency services.

authorStream Live Help