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Earthquake and Tsunami

By- Mayank

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Earthquakes: Basics

Earthquakes occur along a fault or fault system.

Epicenter = the location on the earths surface directly above the originof the earthquake.

Magnitude is a measure of how much energy is released in alldirections.

Bigger faults make bigger earthquakes

Bigger earthquakes last a longer time

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Earthquakes: Facts

Earthquakes can not be predicted. However based onscientific data, probabilities can be calculated for potentialfuture earthquakes.

Earthquakes are equally as likely to occur at any time of theday or month or year.

There is no connection between the weather and earthquakes

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Tsunami: Overview

Tsunami is a Japanese word, which means harbourwave.

Tsunami is a series of large waves of extremely highwavelength and period which travels in all directions away

from point of impact.

Tsunami is one of the most destructive natural disaster whichcause loss of life and property on large extent.

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Tsunami: Causes

Volcanic eruptions Earthquakes

Icefalls

Heavy rainfall

Submarine landslides

Cosmic impacts

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Tsunami: Causes (Earthquake)

Seismic activity is most common for tsunamis. Both tectonicand subduction earthquakes near ocean create tsunamis.

In tectonic earthquake, sea water become deformed, forcingdisplacement of water.

In subducation earthquake, tectonic plates slip under each

other, create massive disturbance and cause displacement ofwater.

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Tsunami: Causes (Earthquake)

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The Sumatran Tsunami

The Sumatran tsunami occurred on the 26th December 2004,following an undersea earthquake off the west coast ofSumatra, Indonesia.

It killed over 225,000 people in 11 countries and is noted as themost catastrophic natural disaster to date.

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The Sumatran Tsunami

The earthquake that caused the Sumatran tsunami is thesecond largest to ever be recorded on a seismograph.

The magnitude of the earthquake was 9.3 on the Richter scale.

This earthquake had the longest duration, that is lasted for thelongest amount of time, ever observed, lasting approximately10 minutes.

It caused the entire planet to vibrate by as much as 1 cm (0.5

inches), and triggered other earthquakes as far away asAlaska.

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The Lisbon Earthquake

The Great LisbonEarthquake took place onthe 1st November 1755. Itwas followed by a tsunami

and a fire, that almostdestroyed the citycompletely.

The death toll has beenplace between 60,000 and100,000, making it one ofthe worst earthquakes in

history. On the right is a copper

carving showing the city ofLisbon in flames, and boatsbeing overturned by theforce of the tsunami.

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More Tsunamis of the past

One of the worst tsunami disasters engulfed whole villages alongSanriku, Japan, in 1896. A wave more than seven stories tall (about 20m) drowned some 26,000 people.

1946: An earthquake in the Aleutian Islands sent a tsunami to Hawaii,killing 159 people (five died in Alaska).

1958: A very localized tsunami in Lituya Bay, Alaska was the highestever recorded: more than 500 m (1500 ft) above sea level. It did notextend much beyond the outlet of the fjord in which it occurred but didkill two people in a fishing vessel.

1976: August 16 (midnight) a tsunami killed more than 5000 people inthe Moro Gulf region Cotabato city) of the Philippines.

1983: 104 people in western Japan were killed by a tsunami spawnedfrom a nearby earthquake.

July 17, 1998: A Papua New Guinea tsunami killed roughly 2200 people.A 7.1 magnitude earthquake 15 miles offshore was followed within 10

minutes by a tsunami about 12 m tall.

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Preventions

Loss of life and property can be reduced by proper planning.

Tsunami warnings can be made to aware peoples.

Stay away from all low lying coastal areas.

Never go down to the shore to watch tsunami.

Stay out of low lying danger areas until an all-clear is issuedby competent authority.