PRESENTATION ON EARTHQUAKE

Prepared by :

Nirav R Dabhi 11CLD09Simal B Gandhi 11CLD10Parth J Bhavsar 11CLD12 Ketul P Mandavia 11CLD14

SILVER OAK COLLEGE OF ENGINEERING & TECHNOLOGY

Adviser :

Dulari MehtaKhushbu Bhojak

• An earthquake (also known as a quake, tremor or temblor) is theresult of a sudden release of energy in theEarth's crust thatcreatesseismic waves.

• An earthquakeis caused by a sudden rupture (break) of the earth

• The most largest earthquakeof 9.5 magnitudeearthquakein• The most largest earthquakeof 9.5 magnitudeearthquakeinChile in 1960.

• The most recent earthquake of9.0 magnitude earthquake inJapan in 2011(as of March 2011), and it was the largest Japaneseearthquake since records began.

• It struck at 7.58amon December 26, 41 miles off the coast ofnorth-west Sumatra where 200,000 are nowthought to have beenkilled in just 15 minutes.

• Passing the Elastic Limit Causes Faulting

• Applied stresses can cause rocks to bend and stretch• Eventually rocks will break away fromone another• Area in which the rocks break and move is called a fault• Vibrations produced is called an earthquake• Earth’s crust movement causes the stresses applied

• Response of material to the arrival of energyfronts released by rupture

• Two types:• Bodywaves• Bodywaves

• P and S• Surface waves

• R and L

• P or primary waves• Fastest waves• Travel through solids,

liquids, or gases• Compression wave,

material movement isin thesamedirectionas

• Body waves

material movement isin thesamedirectionaswave movement

• Energy waves thatcause rocks to moveback and force in thesame direction

• Compression andstretching forces arecreated

••

• S or secondary waves• Slower than P waves• Travel through solids

only• Shear waves - move

material perpendicularto wavemovementto wavemovement

• Energy waves thatcause rocks to move atright angles to thewave

• Surface Waves• Travel just belowor along the ground’s surface• Slower than body waves; rolling and side-to-side

movement• Especially damaging to buildings• Energy waves that move rocks in an elliptical motion

• Earthquake focus• Focus – the point in Earth’s

interior where the energywaves are produced

• Seismicwaves

Seismic waves do not travel through earth’s surface at the same speedPrimary waves are the fastestSurface waves are the slowest

• Seismicwaves• Seismic wave - the energy

waves that move outward fromthe earthquake focus and makethe ground quake

• Epicenter• The point on Earth’s surface

directly above the earthquakefocus

• Earth’s plates moveapart

• Movement of the platescauses tensionRocks above the fault

• Normal Fault

• Rocks above the faultsurface move downwardin relation to the rocksbelowthe fault surface

• Compression forces areapplied because Earth’splates are comingtogether

• Causes rocks to bend

• Reverse Faults

and break

• Rocks above the faultsurface are forced upand over the rocksbelowthe fault surface

• Earth’s plates movesideways to oneanother

• Creates a shear force

• Rocks on either side

• Strike-slip Fault

• Rocks on either sideof the fault surfaceare moving past eachother without muchupward or downwardmovement

• Record the informationfrom the earthquake byrecording the different

• Seismograph stations

recording the differenttypes of waves as theyreach the station

• If information is receivedfrom the earthquake atthree stations, then theepicenter can be located

• A circle is drawn aroundeachstationonamap

• Epicenter Location

eachstationonamap• The radius is equal to the

distance fromthe stationto the epicenter

• The point in which allthree circles intersect isthe earthquake epicenter

• Seismology• Seismologists - People who study earthquakes and seismic

waves

• Use instruments called seismographs

• Recordseismicwaves• Recordseismicwaves

• A drum with a sheet of paper vibrates and a stationarypen marks the vibrations on the paper

• The height of the lines are used to measure the energyreleased fromthe earthquake called the magnitude

• Earthquake Magnitude• Usually determines the strength of the break

• Doesn’t determine the duration or the size

• For each increase of 1 is 10 times stronger

• An earthquake of 4 is 10 times stronger than an earthquakeof 3

Causedby themovementof theoceanfloor• Causedby themovementof theoceanfloor• Causes a disruption in the water

• Some are so wide that a large ship can travel over the wavewithout knowing

• Recent earthquake in the Indian Ocean created a tsunamisthat was 100 feet high and moving at 500 mph

• Shaking and Ground rupture

• Shaking and groundrupture are the maineffects created byearthquakes, principallyearthquakes, principallyresulting in more or lesssevere damage tobuildings and other rigidstructures.

• The severity of the local effects depends on the complexcombination of the earthquakemagnitude, the distancefrom the epicenter, and the local geological andgeomorphologic conditions, which may amplify or reducewave propagation.

• The ground-shaking is measured byground acceleration.

• Landslides and avalanches

• Earthquakes, along withsevere storms, volcanicactivity, coastal waveattack, and wildfires, canproduce slope instabilityleading to landslides, aleading to landslides, amajor geological hazard.

• Landslide danger maypersist while emergencypersonnel are attemptingrescue.

• Fires

• Earthquakes can causefiresby damaging electricalpower or gas lines. In theevent of water mainsrupturing and a loss ofpressure, it may also becomedifficult to stopthespreadofdifficult to stopthespreadofa fire once it has started.

• For example, more deathsin the 1906 San Franciscoearthquakewere caused byfire than by the earthquakeitself.

• Soil liquefaction

• Soil liquefaction occurswhen, because of theshaking, water-saturatedgranular material (such assand) temporarily loses itsstrength and transformsstrength and transformsfrom asolid to aliquid.

• Soil liquefaction maycause rigid structures, likebuildings and bridges, to tiltor sink into the liquefieddeposits.

• This can be a devastating effect of earthquakes. Forexample, in the1964 Alaska earthquake, soil liquefactioncaused many buildings to sink into the ground, eventuallycollapsing upon themselves.

• Tsunami

• Tsunamis are long-wavelength, long-period seawaves produced by the suddenor abrupt movement of largevolumes of water.

• In the open ocean the• In the open ocean thedistance between wave crestscan surpass 100 kilometers(62 mi), and the wave periodscan vary fromfive minutes toone hour.

• Such tsunamis travel 600-800 kilometers per hour (373–497miles per hour), depending on water depth.

• Large waves produced by an earthquake or a submarinelandslide can overrun nearby coastal areas in a matter ofminutes.

• Tsunamis can also travel thousands of kilometers across openocean and wreak destructionon far shoreshours after theocean and wreak destructionon far shoreshours after theearthquake that generated them.

• Floods

• A flood is an overflowofany amount of water thatreaches land.

• Floods occur usually whenthe volume of water within abody of water, such as abody of water, such as ariver or lake, exceeds thetotal capacity of theformation, and as a resultsome of the water flows orsits outside of the normalperimeter of the body.

• However, floods may be secondary effects ofearthquakes, if dams are damaged.

• Earthquakes may cause landslips to damrivers, whichcollapse and cause floods.

• Human impacts

• An earthquake may causeinjury and loss of life, road andbridge damage, generalproperty damage(which mayor may not be covered byearthquake insurance), andcollapse or destabilizationcollapse or destabilization(potentially leading to futurecollapse) of buildings.

• The aftermath may bringdisease, lack of basicnecessities, and higherinsurance premiums.

• Seismic safe structures• Structures that are resistant to the vibrations of Earth’s

crust

• Structures are made with moorings

• Made of steel and are filled with alternating layers of• Made of steel and are filled with alternating layers ofrubber and steel

• These structures absorb the energy produced fromtheearthquake

Damage in Oakland, CA, 1989• Building

collapse• Fire• Tsunami• Ground failure