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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issued a tsunami warning along the coasts of the prefectures of Ishikawa, Niigata, and Toyama; however, it was later withdrawn.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  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 

Divergent boundary -A divergent border is the result of two tectonic plates moving apart. Magma, or molten rock, rises to the surface of the Earth from the mantle and solidifies to form new oceanic crust along these borders, causing frequent earthquakes. Mid-Atlantic Ridge, for example

Convergent boundary: the point at which two plates converge.One or both of the plates may bend downward forming a deep undersea trench or the margins of the colliding plates may buckle up into mountain ranges. Along convergent plate borders, a chain of volcanoes frequently arises, and strong earthquakes frequently occur. Pacific Ring of Fire, for instance

Transform plate boundary: A transform plate boundary is created when two plates move past one another. An example is the San Andreas fault zone.

How prone is India from earthquake ?

(a)  Approximately 59% of India's landmass is vulnerable to earthquakes of different magnitudes, according to the government.

(b)Eight states and Union Territories have cities and towns in zone 5, which puts them at danger of the strongest earthquakes.

(c)The second-highest level, zone-4, includes the National Capital Region.Other notable earthquakes that have occurred in the region of Delhi-NCR throughout documented history include the ones in Mathura (1803) and Bulandshahr (1956).

(d)Zone 2 experiences the least powerful earthquakes, while Zone 5 experiences the strongest ones. The country's land area is divided into zones 5 and 2, with 11% in Zone 5, 18% in Zone 4, 30% in Zone 3, and the remainder in Zone 2.

Risk mitigation strategy

    • Establishment of NDRF National disaster response force  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).         
    • seismic retrofitting -the process of improving existing structure to increase  increase their resistance to seismic activity, ground motion, or soil failure brought on by earthquakes is known as seismic retrofitting.
    • 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  - 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 

Question -  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