Earthquake Belts – Geology Notes – For W.B.C.S. Examination.

ভূমিকম্প বলয়  গুলী – ভূতত্ত্ব নোট – WBCS পরীক্ষা।

Seismic Belts are the narrow geographic zone on the Earth’s surface along which most earthquake activity occurs. As the lithosphere is made up of several large tectonic plates. The edges where these plates move against one another are the location of interplate earthquakes that produce the seismic belts. Island arcs, mountain chains, volcanism, deep ocean troughs, and oceanic ridges are often features of seismic belts.Continue Reading Earthquake Belts – Geology Notes – For W.B.C.S. Examination.

There are 3 main Seismic belts around the world:

• Pacific Seismic Belt
• Mid Oceanic Ridge Belt
• Alpine Himalayan Seismic Belt
  

  PACIFIC SEISMIC BELT

  It is the biggest Seismic belt of all. It is an area where large number of Earthquakes and Volcanic Eruptions occur in the basin of Pacific Ocean. It is also known as “The Ring of Fire” as the volcanoes are associated with the belt throughout its length. It includes 452 volcanoes which are 75% of theworld’s active and dormant volcanoes.

  This belt runs upto 40000 km. The Ring of Fire encapsulates several tectonic plates including the vast Pacific Plate and the smaller Phillipine, Juan de Fuca, Cocos and Nazca Plates it border. (Juan De Fuca is the smallest plate of all plates). Along the west Coast of North America the Pacific plate is in the process of sliding past of the North American plate that intersection forms an active Transform fault. It has been settling for several of the largest Earthquake in the recorded history.

  • Chile Earthquake of 1960
  • Alaska Earthquake of 1964
  • Japan Earthquake of 2011
  • the earthquake that produced the devastating Indian Ocean Tsunami of 2004.

  ALPINE HIMALAYAN SEISMIC BELT

  • It includes an array of mountain ranges extending along the Southern margin of Eurasia stretching from Java to Sumatra through the Himalayas, the Mediterranean out into the Atlantic.
  • It includes the Alps, Iran, The Hindu Kush and the mountains of South-East Asia.
  • It is the second most seismically active region of the world.
  • The belt is the result of Mesozoic to Cenozoic to recent closure of the Tethys Ocean and the process of collision between the Northward moving African, Arabian, and Indian plates with the Eurasian Plate.
    

    MID OCEANIC RIDGE BELT

    It is one of the longest active Seismic belts where most of the Earthquake epicentres are located continuously with a narrow axial zone. The total length of this belt is around 70000 km.

    Geological and Geophysical observations revealed a portioning of the ridge by numerous discontinuities of several orders, which is reflected in the seismicity. The total seismic budget of the Mid Oceanic Ridge increases with higher spreading rate.

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