Combining pre-disaster optical and post-disaster synthetic aperture radar (SAR) satellite data is essential for the timely damage investigation because the availability of data in a disaster area is usually limited. This article proposes a novel method to assess damage in urban areas by analyzing combined pre-disaster very high resolution (VHR) optical data and post-disaster polarimetric SAR (PolSAR) data, which has rarely been used in previous research because the two data have extremely different characteristics. To overcome these differences and effectively compare VHR optical data and PolSAR data, a technique to simulate polarization orientation angles (POAs) in built-up areas was developed using building orientations extracted from VHR optical data. The POA is an intrinsic parameter of PolSAR data and has a physical relationship with building orientation. A damage level indicator was also proposed, based on the consideration of diminished homogeneity of POA values by damaged buildings. The indicator is the difference between directional dispersions of the pre and post-disaster POA values. Damage assessment in urban areas was conducted by using the indicator calculated with the simulated pre-disaster POAs from VHR optical data and the derived post-disaster PolSAR POAs. The proposed method was validated on the case study of the 2011 tsunami in Japan using pre-disaster KOMPSAT-2 data and post-disaster ALOS/PALSAR-1 data. The experimental results demonstrated that the proposed method accurately simulated the POAs with a root mean square error (RMSE) value of 2.761 • and successfully measured the level of damage in built-up areas. The proposed method can facilitate efficient and fast damage assessment in built-up areas by comparing pre-disaster VHR optical data and post-disaster PolSAR data.superior to an optical sensor due to its relative insensitivity to the weather and illumination conditions. Several studies have investigated disaster-induced damage using pre and post-disaster SAR data [1][2][3][4][5][6]. Recently, damage investigation has been improved using fully polarimetric SAR (PolSAR) data because it allows more efficient results with its additional polarization scattering mechanism compared to a single polarization mode [5,6].However, pre-disaster SAR data is less abundant than pre-disaster optical data because optical sensors have traditionally been used. Therefore, the combination of pre-disaster optical data and post-disaster SAR data is regarded as desirable for rapid damage assessment [7]. Due to the significant radiometric and geometric differences between optical and SAR data, it is practically impossible to directly compare the two data. The previous studies using both data have been focused on well integrating different types of information derived from each data for land cover and land use mapping [8][9][10][11]. The research comparing the two data, particularly the pre-disaster optical data and the post-disaster SAR data, for damage mapping has been relatively less conducted [7,12].To overco...