Muldrow Glacier (McKinley Glacier) is a large glacier in Denali National Park and Preserve in Alaska, USA. It is now moving 100 times faster than normal, which means that it is undergoing a "surge".
The abrupt acceleration of the glacier movement is clearly visible in the recent series of Sentinel-1 SAR backscatter images (animation below). Also visible is a strong increase in the backscatter due to the formation of new crevasses. These crevasses create new reflectors on which the radar waves can bounce and return to the satellite antenna.
update 18 Oct 2021
One year time lapse of surging Muldrow glacier in Alaska (update of the #Sentinel1 time series https://t.co/BdE1ZsdBRD) @CopernicusEU @DenaliNPS
More here: https://t.co/JaHnMj8XmR pic.twitter.com/kqFTY6P5zt
— Simon Gascoin (@sgascoin) October 17, 2021
Read more about the Muldrow Glacier surge and the ongoing effort to study it : https://www.nps.gov/articles/dena-muldrow.htm