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02 Jan 24

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UPSC MAINS SYLLABUS GS3 PAPER : DISASTER AND DISASTER MANAGMENT

WHY IN NEWS?

On Monday afternoon, a powerful earthquake with an estimated preliminary magnitude of 7.6 struck north-central Japan. The Japan Meteorological Agency promptly issued a tsunami warning along the coasts of the prefectures of Ishikawa, Niigata, and Toyama; however, it was later withdrawn.

WHAT IS AN EARTHQUAKE┬а AND TSUNAMI?

EARTHQUAKE- any abrupt earth trembling brought on by seismic waves passing through the rocks of Earth. The quick release of energy from the Earth's crust, typically caused by the sudden fracture and "slip" of masses of rock under strain, is what causes seismic waves. Most earthquakes happen at geologic faults, which are slender areas where different rock masses move in respect to one another. The major global fault lines are found at the edges of the massive tectonic plates that comprise the crust of the Earth.

TSUNAMI-Tsunamis are giant waves caused by earthquakes or volcanic eruptions under the sea. Out in the depths of the ocean, tsunami waves do not dramatically increase in height. But as the waves travel inland, they build up to higher and higher heights as the depth of the ocean decreases. The speed of tsunami waves depends on ocean depth rather than the distance from the source of the wave.

Different types of plate tectonic due to which earthquake happens┬а

Divergent boundary -A┬аdivergent┬аborder┬аis┬аthe┬аresult┬аof┬аtwo┬аtectonic┬аplates┬аmoving┬аapart. Magma,┬аor┬аmolten┬аrock,┬аrises┬аto┬аthe┬аsurface┬аof┬аthe┬аEarth┬аfrom┬аthe┬аmantle┬аand┬аsolidifies┬аto┬аform┬аnew┬аoceanic┬аcrust┬аalong┬аthese┬аborders,┬аcausing┬аfrequent┬аearthquakes. Mid-Atlantic┬аRidge,┬аfor┬аexample

Convergent┬аboundary:┬аthe┬аpoint┬аat┬аwhich┬аtwo┬аplates┬аconverge.One┬аor┬аboth┬аof┬аthe┬аplates┬аmay┬аbend┬аdownward┬аforming┬аa┬аdeep┬аundersea┬аtrench┬аor┬аthe┬аmargins┬аof┬аthe┬аcolliding┬аplates┬аmay┬аbuckle┬аup┬аinto┬аmountain┬аranges. Along┬аconvergent┬аplate┬аborders,┬аa┬аchain┬аof┬аvolcanoes┬аfrequently┬аarises,┬аand┬аstrong┬аearthquakes┬аfrequently┬аoccur. Pacific┬аRing┬аof┬аFire,┬аfor┬аinstance

Transform┬аplate┬аboundary:┬аA┬аtransform┬аplate┬аboundary┬аis┬аcreated┬аwhen┬аtwo┬аplates┬аmove┬аpast┬аone┬аanother. An┬аexample┬аis┬аthe┬аSan┬аAndreas┬аfault┬аzone.

How prone is India from earthquake ?

(a)┬а Approximately┬а59%┬аof┬аIndia's┬аlandmass┬аis┬аvulnerable┬аto┬аearthquakes┬аof┬аdifferent┬аmagnitudes,┬аaccording┬аto┬аthe┬аgovernment.

(b)Eight┬аstates┬аand┬аUnion┬аTerritories┬аhave┬аcities┬аand┬аtowns┬аin┬аzone┬а5,┬аwhich┬аputs┬аthem┬аat┬аdanger┬аof┬аthe┬аstrongest┬аearthquakes.

(c)The┬аsecond-highest┬аlevel,┬аzone-4,┬аincludes┬аthe┬аNational┬аCapital┬аRegion.Other┬аnotable┬аearthquakes┬аthat┬аhave┬аoccurred┬аin┬аthe┬аregion┬аof┬аDelhi-NCR┬аthroughout┬аdocumented┬аhistory┬аinclude┬аthe┬аones┬аin┬аMathura┬а(1803)┬аand┬аBulandshahr┬а(1956).

(d)Zone┬а2┬аexperiences┬аthe┬аleast┬аpowerful┬аearthquakes,┬аwhile┬аZone┬а5┬аexperiences┬аthe┬аstrongest┬аones. The┬аcountry's┬аland┬аarea┬аis┬аdivided┬аinto┬аzones┬а5┬аand┬а2,┬аwith┬а11%┬аin┬аZone┬а5,┬а18%┬аin┬аZone┬а4,┬а30%┬аin┬аZone┬а3,┬аand┬аthe┬аremainder┬аin┬аZone┬а2.

Risk mitigation strategy

    • Establishment of NDRF National disaster response force┬а in 2006 , to provide the specialist response in any disaster situations like earthquake.
    • Structural -There are several different experimental techniques that can be used to test the response of structures to verify their seismic performance, one of which is the use of an earthquake shaking table (a shaking table, or simply shake table).┬а ┬а ┬а ┬а ┬а
    • seismic retrofitting -the process of improving existing structure to increase ┬аincrease┬аtheir┬аresistance┬аto┬аseismic┬аactivity,┬аground┬аmotion,┬аor┬аsoil┬аfailure┬аbrought┬аon┬аby┬аearthquakes┬аis┬аknown┬аas┬аseismic┬аretrofitting.
    • Seismic hazard mapping - thorough analysis of potential danger spots in the region and demarcation of different zones based on the potential risk factor.
    • International cooperation among countries to mitigate the affect of earthquake through sharing the risk assessment, new technology and protocol. Example -Sendai framework.
    • Education and informative campaigns┬а - Educate the public about earthquake risks and safety measures through awareness campaigns. Conduct regular drills and training sessions for schools, businesses, and communities.

Way forward

Earthquake is one of the deadly disaster that occurs without any prior notice there is an urgent to be updated about the modern mitigation strategies , that can significantly reduce the loss of lives as well as property.

PRELIMS QUESTION

Consider the following statements regarding seismic waves and their effects:

    1. Seismic waves are classified into two main types: body waves and surface waves.
    2. P-waves (primary waves) are compressional waves that travel through the Earth's interior, including solids and liquids.
    3. Richter scale measures the magnitude of earthquakes based on the amplitude of seismic waves.
    4. Tsunamis are primarily caused by underwater volcanic eruptions, not seismic activity.

How many of the following statements are correct?

(A)only one

(B)only two

(C)only three

(D)all four

Answer- (c) fourth statement is wrong tsunami are caused by both volcanic activities and seismic activities.

Mains Question┬а

Question -┬а In light of recent earthquake in Japan, Mention the different types of plate tectonics and also mention some risk mitigation strategy for earthquakes?

SOURCES- NOAA, Britannica, INDIA today