Bad weather conditions after great earthquakes usually hamper the usability of optical remote sensing, so all day and all weather SAR can provide useful information for quick damage assessment at an early stage when field survey for a large area is difficult. SAR is strongly sensitive to surface changes, and earthquake caused serious damage and building collapse modify the electromagnetic behaviour, so that damage detection from SAR images acquired pre- and post-earthquake becomes possible. However, the characteristics of SAR data, such as worse visual effect, lower spatial resolution and more complicated data processing compared to optical remote sensing data, usually limited its quick applications to disaster monitoring and management to some degree