The Mw9.0 Tohoku Earthquake that occurred on March 11, 2011, off the Pacific coast of northeaster... more The Mw9.0 Tohoku Earthquake that occurred on March 11, 2011, off the Pacific coast of northeastern (Tohoku) Japan caused gigantic tsunamis, resulting in widespread devastation and crustal movements. In a previous study, we proposed a method for capturing the two-dimensional (2D) surface movements from pairs of temporal intensity images, based on the high orbit accuracy of the satellite TerraSAR-X (TSX). Detecting three-dimensional (3D) displacement from a single pair of TSX images is difficult, and thus in the present study we used three pairs of TSX images taken in the ascending and descending paths to estimate 3D crustal movements. First, the 2D crustal movements due to the 2011 Tohoku earthquake were detected from three respective pairs of images. We derived the relationship between the 3D displacement and the 2D converted movement in synthetic aperture radar (SAR) images according to the observation model and acquisition conditions of the SAR sensor. We then estimated the 3D mov...
The relationship between the amplification ratio of earthquake ground motion and geologic conditi... more The relationship between the amplification ratio of earthquake ground motion and geologic conditions at Japan Meteorological Agency (JMA) stations nationwide was examined to propose an estimation method of the amplification ratio that is applicable to entire Japan. The amplification ratios for the instrumental JMA intensity, as well as for the peak ground acceleration and velocity, were obtained from the station coefficients of the attenuation relationships using strong motion records measured at 77 JMA stations over a period of more than 8 years. A combined use of geomorphological land classification and subsurface geology was found to yield the best estimate of the site amplification ratio. This result suggests that these data, and hence the Digital National Land Information, which is a nationwide GIS database, may be conveniently used for the estimation of strong motion distribution over large areas in Japan.
This study tried to detect collapsed bridges due to tsunami by analyzing changes of backscatterin... more This study tried to detect collapsed bridges due to tsunami by analyzing changes of backscattering intensity in Synthetic Aperture Radar (SAR) images. TerraSAR-X images covering the Sendai and Ishinomaki planes acquired before and after the 2011 Tohoku-Oki earthquake were employed together with the GIS data of bridges. The bridge region was created according the GIS data with a 10-m buffer. Then the difference and correlation coefficient of the sigma naught values within the bridge region were obtained. The proper threshold value of the correlation coefficient was investigated to extract collapsed bridges. In order to verify the effectiveness of the method, the extracted results were compared with the reference data from damage investigation reports and aerial photographs. The threshold vale of the correlation coefficient, 0.47, gave the highest value for the summation of the producer accuracies for collapsed and survived bridges, with the overall accuracy 0.776 and the kappa coefficient 0.430.
Damage estimation for scenario earthquakes is extensively carried out by local governments in Jap... more Damage estimation for scenario earthquakes is extensively carried out by local governments in Japan for emergency response planning. However, local governments usually do not possess detailed grid data of lifeline systems with pipe material, diameter and length's information in the grid cell of GIS. The accuracy of lifeline's mesh data is considered to be highly related to the accuracy of damage assessment results. Therefore, to improve the accuracy of earthquake damage assessment, a correlation analysis is carried out to estimate the sewer pipeline length within a grid cell of 250 m from the corresponding road network's GIS data for Urayasu city, Chiba prefecture, Japan. The estimated sewer pipeline lengths were compared with the actual lengths from the GIS network data, and the efficiency of the estimation method from road network data is demonstrated.
In order to detect the flood damage of flood or tsunami, we assessed quantitatively the flood dam... more In order to detect the flood damage of flood or tsunami, we assessed quantitatively the flood damage by calculating water occupancy in each pixel of optical satellite imagery using Spectral Mixture Analysis (SMA). We applied the SMA for flood event in Bangkok, Thailand, 2011 and compared the result of SMA and visual interpretation from IKONOS image for accuracy velidation. Additionally, we developed an estimation model for calculating the water occupancy based on satellite SAR observation, comparing backscattering coefficients of the ALOS PALSAR image and the water fraction information derived from SMA method, which is applied to the Landsat-7 ETM+ reflectance image observing the 2011 Tohoku earthquake tsunami. By using our proposed formula and SAR imagery after water-induced disasters, we can perform to estimate flooded areas easily and quantitatively.
Post-disaster urban recovery is a significant matter in disaster management that represents gover... more Post-disaster urban recovery is a significant matter in disaster management that represents government efforts after a disaster and victim satisfaction with these efforts in affected areas. Understanding the recovery process is a procedure necessary for evaluating government strategy. From this view, the authors dealt with the recovery process at Pisco, the area most devastated in the 2007 Peru Earthquake. Research was conducted through the following procedure: (1) a field survey including interviews was carried out in July 2012 to clarify post-earthquake conditions in urban Pisco, especially from the viewpoint of the physical environment, (2) recovery conditions were compared with damage conditions investigated by CISMID just after the event using satellite imaging and building recovery data obtained in the survey, and (3) post-earthquake recovery was quantitatively analyzed in terms of building recovery. Results indicated that 93.2% of seriously or severely damaged buildings had b...
Demonstrate the possibility and limitation of detecting moving objects from a QuickBird (QB) scen... more Demonstrate the possibility and limitation of detecting moving objects from a QuickBird (QB) scene using a slight time lag (=0.2 seconds) between panchromatic (PAN) and multi-spectral (MS) sensors. Develop a new object-based method to extract moving vehicles and subsequently detect their speeds from two consecutive aerial images automatically. 4 Contents Time lag in QB images and moving objects seen in Google Earth Visual inspection of vehicle speed from QB images Detection of vehicle speed from digital aerial images Automated detection of vehicles from aerial images
2010 Ieee International Geoscience and Remote Sensing Symposium, Jul 25, 2010
Shadows in remote sensing images often result in problems for many applications such as land-cove... more Shadows in remote sensing images often result in problems for many applications such as land-cover classification, change detection, and damage detection in disasters. Due to these reasons, it is very useful if the radiance of shadowed areas is corrected to the same radiance as shadow-free areas. In this study, a shadow detection and correction method is proposed. Shadowed areas are detected by object-based classification, using brightness values and a neighbor relationship. Then the detected shadowed areas are corrected by a liner function to produce a shadow-free image. The shadowed areas with different darkness are corrected with different ratios to improve the accuracy of the result. The spectral characteristics of sunlit and shadowed areas in several QuickBird images were studied and then the shadow-free radiance was obtained.
A new object-based method is developed to extract moving vehicles and subsequently detect their s... more A new object-based method is developed to extract moving vehicles and subsequently detect their speeds from two consecutive images automatically. Several global and local parameters of gray values and sizes are examined to classify the objects in the image. Vehicles and their associated shadows can be discriminated by removing big objects such as roads. To detect speed, firstly vehicles and shadows are extracted from two consecutive images. The corresponding vehicles from the two images are then linked based on the similarity in shape and size and on the distance within a threshold. Finally, using the distance between the corresponding vehicles and time lag between two images, we can detect the moving speed and azimuth angle. Our test shows promising results for detecting vehicles speeds. Further development will employ the proposed method to a pair of QuickBird panchromatic and multi-spectral images, which are at a coarser spatial resolution.
The Mw9.0 Tohoku Earthquake that occurred on March 11, 2011, off the Pacific coast of northeaster... more The Mw9.0 Tohoku Earthquake that occurred on March 11, 2011, off the Pacific coast of northeastern (Tohoku) Japan caused gigantic tsunamis, resulting in widespread devastation and crustal movements. In a previous study, we proposed a method for capturing the two-dimensional (2D) surface movements from pairs of temporal intensity images, based on the high orbit accuracy of the satellite TerraSAR-X (TSX). Detecting three-dimensional (3D) displacement from a single pair of TSX images is difficult, and thus in the present study we used three pairs of TSX images taken in the ascending and descending paths to estimate 3D crustal movements. First, the 2D crustal movements due to the 2011 Tohoku earthquake were detected from three respective pairs of images. We derived the relationship between the 3D displacement and the 2D converted movement in synthetic aperture radar (SAR) images according to the observation model and acquisition conditions of the SAR sensor. We then estimated the 3D mov...
The relationship between the amplification ratio of earthquake ground motion and geologic conditi... more The relationship between the amplification ratio of earthquake ground motion and geologic conditions at Japan Meteorological Agency (JMA) stations nationwide was examined to propose an estimation method of the amplification ratio that is applicable to entire Japan. The amplification ratios for the instrumental JMA intensity, as well as for the peak ground acceleration and velocity, were obtained from the station coefficients of the attenuation relationships using strong motion records measured at 77 JMA stations over a period of more than 8 years. A combined use of geomorphological land classification and subsurface geology was found to yield the best estimate of the site amplification ratio. This result suggests that these data, and hence the Digital National Land Information, which is a nationwide GIS database, may be conveniently used for the estimation of strong motion distribution over large areas in Japan.
This study tried to detect collapsed bridges due to tsunami by analyzing changes of backscatterin... more This study tried to detect collapsed bridges due to tsunami by analyzing changes of backscattering intensity in Synthetic Aperture Radar (SAR) images. TerraSAR-X images covering the Sendai and Ishinomaki planes acquired before and after the 2011 Tohoku-Oki earthquake were employed together with the GIS data of bridges. The bridge region was created according the GIS data with a 10-m buffer. Then the difference and correlation coefficient of the sigma naught values within the bridge region were obtained. The proper threshold value of the correlation coefficient was investigated to extract collapsed bridges. In order to verify the effectiveness of the method, the extracted results were compared with the reference data from damage investigation reports and aerial photographs. The threshold vale of the correlation coefficient, 0.47, gave the highest value for the summation of the producer accuracies for collapsed and survived bridges, with the overall accuracy 0.776 and the kappa coefficient 0.430.
Damage estimation for scenario earthquakes is extensively carried out by local governments in Jap... more Damage estimation for scenario earthquakes is extensively carried out by local governments in Japan for emergency response planning. However, local governments usually do not possess detailed grid data of lifeline systems with pipe material, diameter and length's information in the grid cell of GIS. The accuracy of lifeline's mesh data is considered to be highly related to the accuracy of damage assessment results. Therefore, to improve the accuracy of earthquake damage assessment, a correlation analysis is carried out to estimate the sewer pipeline length within a grid cell of 250 m from the corresponding road network's GIS data for Urayasu city, Chiba prefecture, Japan. The estimated sewer pipeline lengths were compared with the actual lengths from the GIS network data, and the efficiency of the estimation method from road network data is demonstrated.
In order to detect the flood damage of flood or tsunami, we assessed quantitatively the flood dam... more In order to detect the flood damage of flood or tsunami, we assessed quantitatively the flood damage by calculating water occupancy in each pixel of optical satellite imagery using Spectral Mixture Analysis (SMA). We applied the SMA for flood event in Bangkok, Thailand, 2011 and compared the result of SMA and visual interpretation from IKONOS image for accuracy velidation. Additionally, we developed an estimation model for calculating the water occupancy based on satellite SAR observation, comparing backscattering coefficients of the ALOS PALSAR image and the water fraction information derived from SMA method, which is applied to the Landsat-7 ETM+ reflectance image observing the 2011 Tohoku earthquake tsunami. By using our proposed formula and SAR imagery after water-induced disasters, we can perform to estimate flooded areas easily and quantitatively.
Post-disaster urban recovery is a significant matter in disaster management that represents gover... more Post-disaster urban recovery is a significant matter in disaster management that represents government efforts after a disaster and victim satisfaction with these efforts in affected areas. Understanding the recovery process is a procedure necessary for evaluating government strategy. From this view, the authors dealt with the recovery process at Pisco, the area most devastated in the 2007 Peru Earthquake. Research was conducted through the following procedure: (1) a field survey including interviews was carried out in July 2012 to clarify post-earthquake conditions in urban Pisco, especially from the viewpoint of the physical environment, (2) recovery conditions were compared with damage conditions investigated by CISMID just after the event using satellite imaging and building recovery data obtained in the survey, and (3) post-earthquake recovery was quantitatively analyzed in terms of building recovery. Results indicated that 93.2% of seriously or severely damaged buildings had b...
Demonstrate the possibility and limitation of detecting moving objects from a QuickBird (QB) scen... more Demonstrate the possibility and limitation of detecting moving objects from a QuickBird (QB) scene using a slight time lag (=0.2 seconds) between panchromatic (PAN) and multi-spectral (MS) sensors. Develop a new object-based method to extract moving vehicles and subsequently detect their speeds from two consecutive aerial images automatically. 4 Contents Time lag in QB images and moving objects seen in Google Earth Visual inspection of vehicle speed from QB images Detection of vehicle speed from digital aerial images Automated detection of vehicles from aerial images
2010 Ieee International Geoscience and Remote Sensing Symposium, Jul 25, 2010
Shadows in remote sensing images often result in problems for many applications such as land-cove... more Shadows in remote sensing images often result in problems for many applications such as land-cover classification, change detection, and damage detection in disasters. Due to these reasons, it is very useful if the radiance of shadowed areas is corrected to the same radiance as shadow-free areas. In this study, a shadow detection and correction method is proposed. Shadowed areas are detected by object-based classification, using brightness values and a neighbor relationship. Then the detected shadowed areas are corrected by a liner function to produce a shadow-free image. The shadowed areas with different darkness are corrected with different ratios to improve the accuracy of the result. The spectral characteristics of sunlit and shadowed areas in several QuickBird images were studied and then the shadow-free radiance was obtained.
A new object-based method is developed to extract moving vehicles and subsequently detect their s... more A new object-based method is developed to extract moving vehicles and subsequently detect their speeds from two consecutive images automatically. Several global and local parameters of gray values and sizes are examined to classify the objects in the image. Vehicles and their associated shadows can be discriminated by removing big objects such as roads. To detect speed, firstly vehicles and shadows are extracted from two consecutive images. The corresponding vehicles from the two images are then linked based on the similarity in shape and size and on the distance within a threshold. Finally, using the distance between the corresponding vehicles and time lag between two images, we can detect the moving speed and azimuth angle. Our test shows promising results for detecting vehicles speeds. Further development will employ the proposed method to a pair of QuickBird panchromatic and multi-spectral images, which are at a coarser spatial resolution.
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Papers by Fumio Yamazaki