The Sinking City of Joshimath | In News- Mr. Venkatesan (narrated by Ms.Elsheba) | MCC IAS Academy

The story of a sinking town in Himalayas has been in the news for a while now and this series is dedicated to analysis of various aspects the same.
The Indian Institute of Remote Sensing located in Dehradun said that the city of Joshimath sunk by 5.4 cm between December 27, 2022 and January 8, 2023.
Joshimath or Jyotirmath is located in Chamoli district or Uttarakhand at an altitude of 1875 meters along the banks of the Alakananda River and sandwiched between the Himadri and the Himachal ranges of the Himalayas.
It acts as a gateway to pilgrim centres like Vishnuprayag and Badrinath and is also the closest army station to the Indo-Tibetan Border.
Joshimath also hosts one of the four cardinal institutions established by Adi shankara in 5th century AD causing a revival of vedic Hinduism in the subcontinent. The Jyotir Math holds authority over atharva veda and its mahavakya is Ayam Atman Brahma taken from the Mandukya Upanishad which means the self is the supreme being.
The location of other mathas and their mahavakyas are given for your reference.
The sinking of Joshimath can be attributed to various reasons and the most important of them all is the physical setting of the city. Joshimath is located in seismic zone 5 and hence is prone to high intensity earthquakes.
Seismic zones are demarcated based on historical recordings of earthquakes across the country. The recent seismic zone map is released by Bureau of Indian Standards which demarcates the territory of Bharat into 4 seismic zones as given.
About 11% of our territory is in seismic zone 5 which is shown in red. These territories experiences earthquakes with intensity up to 9 according to the Comprehensive Intensity Scale 64. The Comprehensive intensity scale 64 AKA CIS 64 is a standard to measure earthquake intensity created by BIS. It is based on the Modified Mercalli scale.
About 18% of the territory experiences earthquakes with intensity up to 8 and are categorized as zone 4. Approximately 30% territory experiences earthquakes with intensity up to 7 and 41% territory experiences earthquakes with intensity up to 6 and are categorized as zone 3 and zone 2 respectively.
There are no territories in Bharat that are demarcated as seismic zone 1.
The zoning of Bharat into seismic zones is not a recent process but started in 1935 when geological survey of India released the first seismic zone map for the country after the devastating Nepal-India earthquake. Initially the map had only 3 zone and is subsequently modified in 1962 and 1966 to have 7 zones based on inputs from various other organizations like ISRO. These modifications were done by Bureau of Indian Standards.
After the Koyna Earthquake in Maharashtra new changes were made to the map and number of zones were reduced to 5 in 1970 and 1984 editions. After Latur earthquake in Maharashtra more changes were made and it was ascertained that no place in the country is free from earthquake hazard. As a result the recent version released in 2002 has only 4 seismic zones.
High intense earthquakes occur in places that lie over a fault or shear zone. This earthquake hazard map released by Building Material and Technology Promotion Council of Ministry of Housing and Urban Affaris shows the correlation between major faults and the seismic zones of Bharat.
In the Himalayan region there are 4 major fault lines namely, the Indus Suture between the Ladakh range and Zanskar range over which the Indus river flows, the main central thrust between the Himadri range and the Himachal range, the main boundary thrust between the Himachal range and the Sivalik range and the Himalayan front fault that run along the foothills of the Sivalik range.
All these faults are thrust faults meaning one block of the fault slides down the other block. As the Indian Plate moves in the north east direction there is sinking along these faults.
There are also main minor faults that run alongside these large fault lines.
Joshimath is located slightly to the north of the Main central thrust fault line near the Tapovan fault and Pandukeshwar thrust. The Vaikrita thrust passes through the city. A combination of the plate movement and the thrust experienced along these faults in and around the city causes fracture of the surface and subsequently sinking of the same.
Apart from the seismic activity and tectonic movements there are other possible reasons like formation of underground cave and caverns and creation of isostatic disequilibrium by constructions which we will discuss in subsequent parts.
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Nice explanation man…very useful 😊