academy Earthquake Presented By Bhumika Saini
Earthquake - The shaking or trembling of earth caused by - Usually associated with transient disturbance the sudden release of energy in the underlying rocks It may be due to faulting, folding, plate movement, volcaninc eruptions and anthropogenic factors like dams and reservoirs . Continuing adjustment of position results in aftershocks
Terminology Used in the Study of Earthquakes Earthquake intensity Earthquake magnitude Richter Scale Mercalli Scale Fault Focus Seismic wave Seismograph
The Focus and Epicenter of an Earthquake . The point within Earth where faulting begins is the focus, or hypocenter The point directly above the focus on the surface is the epicenter Epicenter Focus
Fault scarp Epicenter Wave fronts Focus Fault
Measurement 2 parameters- Intensity and magnitude 2 scales - 1. Richter scale- By charles.F. Richter - It measures the magnitude of energy released Scale range from o-9. An earthquake that registers 5.o on the Richter scale has a shaking amplitude 10 times that of an earthquake that registered 4.o, and thus corresponds to a release of energy 31.6 times tha earthquake - t released by the lesser
Richter scale 10 Largest Recorded*** (Offshore Chile, 1960) 8.9 RICHTER SCALE Alaska, 1964 Hew Madrid, MO, 1812 GRAPHIC REPRESENTATION GREAT San Francisco, 1906 E 10 8 Great Devastation Fatalities Possible Loma Prieta, CA, 1989 MAJORand Many SEISMOGRAPH TOO K FROM EPCENTER 10 0 MICRONS 7 1 CM) STRONG O 10 6 MODERATE Damage Be ins Fatalities Rare SMALL 1NOT FELT -1 O1 2 3 4 5 6 7 8 9 MAGNITUDE LOGARITHM (BASE 10) OF MAXIMUM AMPLITUDE MEASURED IN MICRONS
Mercalli intensity scale The Mercalli intensity scale is a seismic scale used for measuring the intensity of an earthquake - It measures the effects of an earthquake Scale range 1-12
Modified Mercalli Scale l Detected only by sensitive instruments 1.5 Felt by few persons at rest, especially l on upper floors; delicately suspended objects may swing Felt noticeably indoors, but not always recognized as earthquake; standing autos| rock slightly, vibration like passing truck 2.5 2.5 Felt indoors by many, outdoors by few, at3 doors disturbed; autos rock noticeably IV night some may awaken; dishes, windows Felt by most people; some breakage V of dishes, windows, and plaster; disturbance of tall objects Felt by all, many frightened and run damage small Everybody runs outdoors; damage to construction; noticed by drivers of autos Panel walls thrown out of frames; fall of .5 mud ejected; drivers of autos disturbed V outdoors; falling plaster and chimneys, 4.5_ VII buildings varies depending on quality of 5 5.5 VIII walls, monuments, chimneys; sand and IX cracked, thrown out of plumb: ground X destroyed; ground cracked, rails XI destroyed, fissures in ground, pipes Buildings shifted off foundations, cracked; underground pipes broken Most masonry and frame structures bent, landslides 6.5 dent, uindinideund cracked, rails7 Few structures remain standing; bridges 7.5 broken, landslides, rails bent Damage total; waves seen on ground XII surface, lines of sight and lev distorted, objects thrown up in air
Seismic Waves - Seismic waves are the waves of energy caused by - They are the energy that travels through the earth - The two main types of waves are body waves and the sudden breaking of rock within the earth They are the energy that travels through the earth and is recorded on seismographs. The two main types of waves are body waves and surface waves.
Body Waves wave (transverse wave) - The second type of body wave is the S wave or secondary wave An S wave is slower than a P wave and can only move through solid rock. This wave moves rock Up and down, or side-to-side. s Wave Double Ampliitude
Surface Waves Rayleigh Waves The other kind of surface wave is the Rayleigh wave, named after Lord Rayleigh - A Rayleigh wave rolls along the ground just like a wave rolls across a lake -Because it rolls, it moves the ground up and down, and side-to-side in or an ocean the same direction that the wave is movin Most of the shaking felt from an earthquake is due to the Rayleigh wave, which can be much larger than the other waves. Rayleigh Wave C>
Surface Waves: R and L waves (a) Rayleigh wave Rayleigh wave Love wave b) Love wave
B Tech from MNIT, Jaipur. Appeared in CSE interview thrice. Loves teaching and playing badminton.