Damage Detection for 2003 Bam, Iran, Earthquake Using Terra-ASTER Satellite Imagery

2005 ◽  
Vol 21 (1_suppl) ◽  
pp. 267-274 ◽  
Author(s):  
Masayuki Kohiyama ◽  
Fumio Yamazaki

The damaged areas of the 2003 Bam, Iran, earthquake were detected using 15-meter-resolution satellite imagery acquired by Terra-ASTER. First, fluctuation of digital numbers was modeled as a normal random variable based on 17 pre-event images on a pixel-by-pixel basis. Then, the deviation value of each digital number in the post-event image was evaluated and converted into the confidence level, which indicates the possibility of an abnormal ground surface change. The detected damaged areas were verified with a high-resolution satellite image and it was observed that the areas with earthquake influence were mostly identified. However, the pixels with significant change were induced not only from heavily damaged buildings but also dusty roads, possibly due to demolition work. It was suggested that prior knowledge like a high-resolution pre-event image would assist the interpretation of the detected result.

Author(s):  
Aymen Al-Saadi ◽  
Ioannis Paraskevakos ◽  
Bento Collares Gonçalves ◽  
Heather J. Lynch ◽  
Shantenu Jha ◽  
...  

2021 ◽  
Author(s):  
Maximillian Van Wyk de Vries ◽  
Shashank Bhushan ◽  
David Shean ◽  
Etienne Berthier ◽  
César Deschamps-Berger ◽  
...  

<p>On the 7<sup>th</sup> of February 2021, a large rock-ice avalanche triggered a debris flow in Chamoli district, Uttarakhand, India, resulting in over 200 dead or missing and widespread infrastructure damage. The rock-ice avalanche originated from a steep, glacierized north-facing slope with a history of instability, most recently a 2016 ice avalanche. In this work, we assess whether the slope exhibited any precursory displacement prior to collapse. We evaluate monthly slope motion over the 2015 and 2021 period through feature tracking of high-resolution optical satellite imagery from Sentinel-2 (10 m Ground Sampling Distance) and PlanetScope (3-4 m Ground Sampling Distance). Assessing slope displacement of the underlying rock is complicated by the presence of glaciers over a portion of the collapse area, which display surface displacements due to internal ice deformation. We overcome this through tracking the motion over ice-free portions of the slide area, and evaluating the spatial pattern of velocity changes in glaciated areas. Preliminary results show that the rock-ice avalanche bloc slipped over 10 m in the 5 years prior to collapse, with particularly rapid slip occurring in the summer of 2017 and 2018. These results provide insight into the precursory conditions of the deadly rock-ice avalanche, and highlight the potential of high-resolution optical satellite image feature tracking for monitoring the stability of high-risk slopes.</p>


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