DANCING OF EARTH – THE EARTHQUAKES

by

K. BHANU PRAKASH REDDY – 14BCE1236

EARTHQUAKE An earthquake (also known as a quake, tremor or temblor) is the result of a

sudden release of energy in the Earth's crust that creates seismic waves.

Earthquakes are measured using observations from seismometers.

The moment magnitude is the most common scale on which earthquakeslarger than approximately 5 are reported for the entire globe. Generally itis traditionally measured by using Richter magnitude scale.

Magnitude 3 or lower earthquakes are mostly almost imperceptible or weakand magnitude 7 and over potentially cause serious damage over largerareas, depending on their depth.

The largest earthquakes in historic times have been of magnitude slightlyover 9. The most recent large earthquake was 9.0 magnitude earthquakein Japan in 2011 (as of March 2014), and it was the largest Japaneseearthquake since records began. Intensity of shaking is measured on the

modified Mercalli scale.

Why Do Earthquakes Happen?

The rocks are still pushing against each other, but not moving. After a while, the rocks breakbecause of all the pressure that's built up. When the rocks break, the earthquake occurs.

During the earthquake and afterward, the plates or blocks of rock start moving, and theycontinue to move until they get stuck again. The spot underground where the rock breaks iscalled the focus of the earthquake. The place right above the focus (on top of the ground) iscalled the epicenter of the earthquake.

Earthquakes are usually caused when rockunderground suddenly breaks along a fault.

This sudden release of energy causes the seismicwaves that make the ground shake.

When two blocks of rock or two plates are rubbingagainst each other, they stick a little. They don't justslide smoothly, the rocks catch on each other.

TRY THIS MINI EXPERIMENT… Break a block of foam rubber in half. Put the pieces on a smooth table. Put the rough edges of the foam rubber pieces

together. While pushing the two pieces together lightly, push one

piece away from you along the table top while pulling theother piece toward you. See how they stick?

Keep pushing and pulling smoothly. Soon a little bit of foam rubber along the crack (the

fault) will break and the two pieces will suddenly slippast each other.

That sudden breaking of the foam rubber is theearthquake. That's just what happens along a strike-slipfault.

EFFECTS OF EARTHQUAKES

Shaking and ground rupture :

Shaking and ground rupture are the main effects created byearthquakes, principally resulting in more or less severe damage tobuildings and other rigid structures.

The severity of the local effects depends on the complex combinationof the earthquake magnitude, the distance from the epicenter, and thelocal geological and geomorphological conditions, which may amplify orreduce wave propagation. The ground-shaking is measured by groundacceleration.

Damaged buildings in Port-au-Prince, Haiti, January 2010.

Specific local geological, geomorphological, and geostructural features can induce high levelsof shaking on the ground surface even from low-intensity earthquakes. This effect is calledsite or local amplification.

It is principally due to the transfer of the seismic motion from hard deep soils to softsuperficial soils and to effects of seismic energy focalization owing to typical geometricalsetting of the deposits.

TSUNAMI:

Tsunamis are long-wavelength, long-period sea wavesproduced by the sudden or abrupt movement of largevolumes of water.

In the open ocean the distance between wave crests cansurpass 100 kilometers (62 mi), and the wave periods canvary from five minutes to one hour. Such tsunamis travel600-800 kilometers per hour (373–497 miles 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 acrossopen ocean and wreak destruction on far shores hours after theearthquake that generated them.

Ordinarily, subduction earthquakes under magnitude 7.5 on theRichter scale do not cause tsunamis, although some instances ofthis have been recorded. Most destructive tsunamis are causedby earthquakes of magnitude 7.5 or more.

FLOODS :

A flood is an overflow of any amount of water that reaches land.

Floods occur usually when the volume of water within a body ofwater, such as a river or lake, exceeds the total capacity of theformation, and as a result some of the water flows or sitsoutside of the normal perimeter of the body.

However, floods may be secondary effects of earthquakes, ifdams are damaged. Earthquakes may cause landslips to damrivers, which collapse and cause floods.

The terrain below the Sarez Lake in Tajikistan is indanger of catastrophic flood if the landslide damformed by the earthquake, known as the Usoi Dam,were to fail during a future earthquake.

Impact projections suggest the flood could affectroughly 5 million people.

Human impacts :

An earthquake may cause injury and loss of life, roadand bridge damage, general property damage, andcollapse or destabilization (potentially leading tofuture collapse) of buildings.

The aftermath may bring disease, lack of basicnecessities, and higher insurance premiums.

LANDSLIDES :

Landslides became a symbol of the devastation the 2001 ElSalvador earthquakes left, killing hundreds in its wake.

Earthquakes, along with severe storms, volcanic activity,coastal wave attack, and wildfires, can produce slopeinstability leading to landslides, a major geological hazard.Landslide danger may persist while emergency personnelare attempting rescue.

FIRES :

Earthquakes can cause fires by damaging electrical power or gas lines. In the event of water mains rupturing and a loss of pressure.

It may also become difficult to stop the spread of a fire once it has started. For example, more deaths in the 1906 San Francisco earthquake were caused by fire than by the earthquake itself.

Soil liquefaction :

Soil liquefaction occurs when, because of the shaking, water-saturated granular material (such as sand) temporarily loses its strength and transforms from a solid to a liquid.

Soil liquefaction may cause rigid structures, like buildings and bridges, to tilt or sink into the liquefied deposits. For example, in the 1964 Alaska earthquake, soil liquefaction caused many buildings to sink into the ground, eventually collapsing upon themselves

Measures against earthquakes

Personal measures :

Seek shelter under stable tables or under door frames.

If outside, stay away from buildings, bridges and electricity pylons and move to open

areas.

Avoid areas at risk from secondary processes, such as landslides, rockfall and soil

liquefaction.

After an earthquake, check gas, water and electricity pipes and lines for damage.

Listen to the radio and follow the instructions issued by the authorities.

What are the most powerful earthquakes of India?

Sr. No. Place Epicenter Date, Time, and Year Magnitude Deaths

1 Indian Ocean West coast of Sumatra, Indonesia

08:50, December 26, 2004

9.1–9.3 > 283,106

2 Kashmir

Muzaffarabad, Pakistan-administered Kashmir

08:50:38, October 8, 2005

7.6 130,000

3 Bihar and NepalSouth of Mount Everest

14 :13, January 15, 1934

8.7 > 30,000

4 Gujarat Kutch, Gujarat08:50:00, January 26, 2001

7.7 20,000

5 Kangra Himalayas 06:10, April 4, 1905 7.8 > 20,000

6 LaturKillari, Latur, Maharashtra

22:25, September 30, 1993

6.4 > 9,748

Sr. No. Place Epicenter Date, Time, and Year

Magnitude Deaths

7 Assam Rima, Tibet19:39, August 15, 1950

8.6 1,526

8 Assam Place name not known

17 :11, June 12, 1897

8.1 1,500

9 UttarkashiGarhwal, Uttarakhand

Unknown time, October 20, 1991

6.8 >1,000

10 Koynanagar Koyna dam, Maharastra

04:21, December 11, 1967

6.5 180

EARTHQUAKE IN NEPAL From few days ago Nepal is being suffering with

earthquake effect. It has been identified that it is of 7.8magnitude with a lot of destruction and loss of lives.

At least 3,617 people are now known to have died in amassive earthquake which hit Nepal on Saturday, police say.

More than 6,500 people have been injured, according to theNational Emergency Operation Centre.

More than 200 climbers have been rescued around MountEverest, which was struck by deadly avalanches

Officials have warned that the number of casualties couldrise as rescue teams reach remote mountainous areas ofwestern Nepal.

Villages like this are routinely affected by landslides, andit's not uncommon for entire villages of 200, 300, up to1,000 people to be completely buried by rock falls.

Dead or missing foreigners

Australia: 549 Australians registered as travelling in Nepal, 200 confirmed safe

Bangladesh: 50 nationals, including members of the country's under-14 girls'football team, evacuated. No information on exact number of nationals in Nepal.

China: Four nationals dead in Kathmandu, Xinhua news agency reports

Colombia: Seven nationals missing

France: French authorities have located 1,098 nationals, but another 674 are stillnot in touch.

UK: Several hundred Britons believed to be in Nepal. No reports of deaths orinjuries.

US: Three Americans killed

CONCLUSION

Finally, it must be understood that this presentation does not exclude the existence (in

the future) of any other methodologies, with even better accuracy than the one,

which has been achieved with the present work.

I hope that some other eager and younger researcher will either improve it or invent a

better one, in the near future.

What is only required, is to believe that a problem shouldn’t be considered

unsolvable, just because it was not solved for a long period of time, in the past.