Satellite radar and optical remote sensing for earthquake damage detection: results from different case studies

Abstract

In case of a seismic event, a fast and draft damage map of the hit urban areas can be very useful, in particular when the epicentre of the earthquake is located in remote regions, or the main communication systems are damaged. Our aim is to analyse the capability of remote sensing techniques for damage detection in urban areas and to explore the combined use of radar (SAR) and optical satellite data. Two case studies have been proposed: Izmit (1999; Turkey) and Bam (2003; Iran). Both areas have been affected by strong earthquakes causing heavy and extended damage in the urban settlements close to the epicentre. Different procedures for damage assessment have been successfully tested, either to perform a pixel by pixel classification or to assess damage within homogeneous extended areas. We have compared change detection capabilities of different features extracted from optical and radar data, and analysed the potential of combining measurements at different frequency ranges. Regarding the Izmit case, SAR features alone have reached 70% of correct classification of damaged areas and 5 m panchromatic optical images have given 82%; the fusion of SAR and optical data raised up to 89% of correct pixel-to-pixel classification. The same procedures applied to the Bam test case achieved about 61% of correct classification from SAR alone, 70% from optical data, while data fusion reached 76%. The results of the correlation between satellite remote sensing and ground surveys data have been presented by comparing remotely change detection features averaged within homogeneous blocks of buildings with ground survey data

Ground Deformation Imagery of the May Sichuan Earthquake

“…Such maps, albeit preliminary, are highly valuable in the aftermath of large disasters, helping to effectively direct the rescue missions. A change image approach (pre-event and postevent image backscattering variation) has been applied [Stramondo et al, 2006] to the radar intensity, and some strong changes in the city of Chengdu, located approximately 80 kilometers from the earthquake epicenter, have been pointed out. Figures 1c and 1d show some details of the presumably damaged structures at a pixel scale of 6 × 6 meters.…”

Infrastructure assessment for disaster management using multi-sensor and multi-temporal remote sensing imagery

“…However, most methods focus on only one single sensor and, thus, the adaptability is limited depending on the availability of data sources after a natural hazard. There are few approaches which analyse the possible advantages of combining different sensors for damage detection (Stramondo et al 2006). The evaluation of individual objects such as damaged bridges is investigated using high-resolution SAR images (Balz et al 2009 Infrastructure assessment 8577 crucial bottlenecks in the transportation systems, in the case of natural hazards a comprehensive assessment system of the whole road network is necessary.…”

“…In particular, the combination of optical and radar images leads to an improved damage assessment (Stramondo et al 2006). The system presented in this article is designed in a flexible way such that the benefits of data fusion can be completely exploited, but it is not dependent on specific sensors.…”

An approach for detection of buildings and changes in buildings using orthophotos and point clouds: A case study of Van Erriş earthquake

“…The applications of remote sensing science and technologies have been broadly utilized for earthquake damage assessment [e.g. San, 2003, 2004;Zhang et al, 2003;Stramondo et al, 2006;Sumer and Turker, 2006;Yu et al, 2010;Chini et al, 2011;Baiocchi et al, 2010Baiocchi et al, , 2011Malinverni, 2011]. Various methods have been designed for building damage assessment either to detect changes between pre-and post-event data or to interpret only post-event data.…”