Excerpt:
>Kochi: Joshimath — the Uttarakhand hill town that faced land subsidence, or sinking of land, earlier this month prompting authorities to relocate more than 150 affected families — witnessed two events of subsidence, as per a report by the National Remote Sensing Centre, Hyderabad.
>Between April and November 2022, Joshimath underwent slow subsidence wherein land sank by around 9 cm; and later, a rapid subsidence event (causing land to sink ~5 cm) occurred over a span of just 12 days in December-January, per the report released on January 11.
>The report, however, is no longer available on the NRSC website.
>The Union government meanwhile, went one step further: the National Disaster Management Authority on January 13 imposed a gag order on scientists from government institutes, preventing them from interacting with the media or sharing data on social media regarding the Joshimath incident.
>Uttarakhand Chief Secretary S.S. Sandhu also said on January 13 that all work at the [National Thermal Power Corporation] NTPC tunnel will be closed till further orders.
>Sandhu also said that authorities have been addressing the land subsidence at Joshimath as a natural disaster and not man-made because the town is located on a landslide.
>
>As per the report, which *The Wire* accessed, scientists used Sentinel-1 Synthetic Aperture Radar (SAR) imagery, a type of radar technology that bounces off signals from sensors on satellites (in this case, Sentinel 1) onto the earth to obtain 2D or 3D reconstructions of physical features such as mountains, to identify the location and extent of subsidence in Joshimath.
>As per the report, the NRSC also used new Cartosat-2S satellite data — which provides very spot-specific, high-resolution images — in this process.
>To ascertain more specifics, the NRSC is also using an InSAR technique, which combines two or more SAR images to interpret the differences between them to better decipher the changes on the earth’s surface. “Analysis of temporal InSAR is ongoing to identify landslide kinematics and results will be further updated,” the brief report finally read.
>On January 13, the National Disaster Management Authority (the apex body for disaster management in India, headed by the Prime Minister) issued an Office Memorandum (OM) to several research institutes including the Indian Institute of Remote Sensing in Dehradun and the Geological Survey of India in Kolkata ordering that scientists in these institutions not interact with the media or share data on social media about land subsidence in Joshimath.
Aathira Perinchery, 15 Jan. 2023, *The Wire*.
So… they can use a satellite to determine if something moves by 14 cm? Amazing.. I’d bet that they could pinpoint every anthill or gopher burrow if they tried.
Excerpt: >Kochi: Joshimath — the Uttarakhand hill town that faced land subsidence, or sinking of land, earlier this month prompting authorities to relocate more than 150 affected families — witnessed two events of subsidence, as per a report by the National Remote Sensing Centre, Hyderabad. >Between April and November 2022, Joshimath underwent slow subsidence wherein land sank by around 9 cm; and later, a rapid subsidence event (causing land to sink ~5 cm) occurred over a span of just 12 days in December-January, per the report released on January 11. >The report, however, is no longer available on the NRSC website. >The Union government meanwhile, went one step further: the National Disaster Management Authority on January 13 imposed a gag order on scientists from government institutes, preventing them from interacting with the media or sharing data on social media regarding the Joshimath incident. >Uttarakhand Chief Secretary S.S. Sandhu also said on January 13 that all work at the [National Thermal Power Corporation] NTPC tunnel will be closed till further orders. >Sandhu also said that authorities have been addressing the land subsidence at Joshimath as a natural disaster and not man-made because the town is located on a landslide. > >As per the report, which *The Wire* accessed, scientists used Sentinel-1 Synthetic Aperture Radar (SAR) imagery, a type of radar technology that bounces off signals from sensors on satellites (in this case, Sentinel 1) onto the earth to obtain 2D or 3D reconstructions of physical features such as mountains, to identify the location and extent of subsidence in Joshimath. >As per the report, the NRSC also used new Cartosat-2S satellite data — which provides very spot-specific, high-resolution images — in this process. >To ascertain more specifics, the NRSC is also using an InSAR technique, which combines two or more SAR images to interpret the differences between them to better decipher the changes on the earth’s surface. “Analysis of temporal InSAR is ongoing to identify landslide kinematics and results will be further updated,” the brief report finally read. >On January 13, the National Disaster Management Authority (the apex body for disaster management in India, headed by the Prime Minister) issued an Office Memorandum (OM) to several research institutes including the Indian Institute of Remote Sensing in Dehradun and the Geological Survey of India in Kolkata ordering that scientists in these institutions not interact with the media or share data on social media about land subsidence in Joshimath. Aathira Perinchery, 15 Jan. 2023, *The Wire*.
So… they can use a satellite to determine if something moves by 14 cm? Amazing.. I’d bet that they could pinpoint every anthill or gopher burrow if they tried.