Details of a Researcher - Kohiyama, Masayuki

Papers - Kohiyama, Masayuki

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Damage Detection from High-Resolution Satellite Images for the 2003 Boumerdes, Algeria Earthquake

Yamazaki, F., Kouchi, K., Matsuoka, M., Kohiyama, M., and Muraoka, N.

13th World Conference on Earthquake Engineering (International Association for Earthquake Engineering) 13 2004.08

Research paper (international conference proceedings), Joint Work

A strong earthquake of magnitude 6.8 struck the Mediterranean coast of Algeria on May 21, 2003 and the cities of Boumerdes and Zemmouri were most heavily damaged. QuickBird satellite observed these areas before and after the earthquake. Based on these images, the present authors performed visual damage detection of buildings. Using the post-event pan-sharpened image only, totally collapsed buildings, partially collapsed buildings, and buildings surrounded by debris were identified. Some buildings were difficult to judge their damage levels, and thus, the pre-event image was also employed as a reference to judge the damage status. By this visual inspection, a total 3,446 buildings were classified in Boumerdes and 1,399 buildings in Zemmouri based on their damage grades. The locations of refugee tents in the two post-event images were also identified. These observations indicate that high-resolution satellite images can provide quite useful information to emergency management after natural disasters.

Vulnerability Functions for Wooden Houses in Japan Based on Seismic Diagnosis Data

Kohiyama, M. and Yamazaki, F.

13th World Conference on Earthquake Engineering (International Association for Earthquake Engineering) 14 2004.08

Research paper (international conference proceedings), Joint Work

The regional difference of seismic capacity of wooden houses in Japan is revealed based on the seismic diagnosis data. The new vulnerability functions of wooden houses, which use the results of seismic diagnosis and an acceleration response spectrum, are proposed. They employ a probability density function of seismic performance indices of wooden houses, which are separated into an index of the resistance force and other indices regarding the degradation of resistance force. The input seismic motion is evaluated based on an acceleration response spectrum and natural periods determined by the indices of resistance force. The application results to the 1995 Hyogo-ken Nanbu earthquake are compared with the damage statistics at the five sites, which have seismic records. Though the proposed vulnerability functions are not based on the damage statistics, the estimated damage ratios coincide fairly well with the actual damage surveyed by local governments.

Early Damaged Area Estimation System Using DMSP-OLS Night-Time Imagery

Kohiyama, M., Hayashi, H., Maki, N., Higashida, M., Kroehl, H. W., Elvidge, C. D., and Hobson, V. R.

International Journal of Remote Sensing (Taylor & Francis) 25 ( 11 ) 2015-2036 2004.06

Research paper (scientific journal), Joint Work, Accepted

The disaster information system, the Early Damaged Area Estimation System (EDES), was developed to estimate damaged areas of natural disaster using the night-time imagery of the Defense Meteorological Satellite Program Operational Linescan System (DMSP-OLS). The system employs two estimation methods to detect the city lights loss or reduction as possible impacted areas; one is the bi-temporal images (BTI) method and the other is the time-series images (TSI) method. Both methods are based on significance tests assuming that brightness of city lights fluctuates as normal random variables, and the BTI method is simplified by introducing the assumption that the standard deviation of city lights fluctuation is constant. The validity of the estimation method is discussed based on the result of the application to the 2001 Western India earthquake disaster. The estimation results identify the damaged areas distant from the epicentre fairly well, especially when using the TSI method. The system is designed to estimate the global urban damage and to provide geographic information through the Internet within 24 h after a severe disaster event. The information is expected to support the disaster response and relief activities of governments and non-governmental organizations.

Damage Detection Method Based on Normal Fluctuation of Digital Numbers in Multi-Temporal Middle-Resolution Images

Kohiyama, M., Estrada, M., and Yamazaki, F.

Monitoring, Prediction and Mitigation of Disasters by Satellite Remote Sensing (MPMD-2004 Symposium) (Disaster Prevention Research Institute, Kyoto University) 123-130 2004.01

Research paper (international conference proceedings), Joint Work

A new damage or change detection method using middle-resolution satellite images is proposed, which employs the probability distribution model of the digital number (DN) fluctuation in a normal condition and its significance test. The DN fluctuation model is formulated by considering imaging process of a satellite sensor and image registration process. The result thematic map is created from the significance level to reject the null hypothesis that the pixel DN can be considered as a sample of the DN fluctuation model. The method overcomes the threshold setting problem in conventional change detection methods.

Law Systems Regarding Seismic Capacity Evaluation of Housing in Japan and Systems Rationalization to Promote House Owners' Action of Seismic Risk Reduction

Masayuki KOHIYAMA, Yuuki ISHIHARA, and Fumio YAMAZAKI

Journal of Social Safety Science (Institute of Social Safety Science) ( 5 ) 113-122 2003.11

Research paper (scientific journal), Joint Work, Accepted

The questionnaire survey on subsidies for seismic diagnosis of private housing was carried out for prefectures and major cities in Japan as of January 2003. The result revealed that 30% of prefectures and 60% of major cities have the subsidies. Though the free-of-charge system gathers more than 100 subsidy users a month, even a small burden charge influences the number of users. The law systems regarding seismic capacity evaluation are reviewed on their purposes and evaluation methods. It is pointed out that the qualified results of seismic diagnosis funded by the subsidies should be used for the discount of earthquake insurance, and the seismic performance should also be certificated for the insurance discount after the retrofit works.

Vulnerability Functions for Wooden Buildings Based on the Data from Seismic Diagnosis –Evaluation of Minor and More Damages Using Acceleration Response Spectrum–

Masayuki KOHIYAMA and Fumio YAMAZAKI

Journal of Structural and Construction Engineering (Transactions of AIJ) (Architectural Institute of Japan) ( 570 ) 137-144 2003.08

Research paper (scientific journal), Joint Work, Accepted

The vulnerability function of wooden-frame houses using the results of seismic diagnosis and a response spectrum was proposed. It employs a probability density function of seismic performance indices of wooden houses, which are separated into an index of horizontal resistance force and other indices. The input seismic motion is evaluated based on an acceleration response spectrum and natural periods determined by indices of horizontal resistance force. The application results to the 1995 Hyogo-ken Nanbu earthquake are compared with the damage statistics at the five sites, which have seismic records. Though the proposed vulnerability function is not based on the damage statistics, the estimated ratios for minor and more damages coincide fairly well with the actual damage surveyed by local governments.

Expansion of the Nishinomiya Built Environment Database - Simulation of seismic ground motion distribution and correlation with damage in the 1995 Hyogo-ken Nanbu Earthquake

Kohiyama, M., Yamashita, N., Sato, T., Lu H., Maki, N., Tanaka, S., and Hayashi, H.

Natural Hazards (Springer) 29 ( 3 ) 501-522 2003.07

Research paper (scientific journal), Joint Work, Accepted

The Nishinomiya Built Environment Database, which can be used to analyze the disaster process of the 1995 Hanshin-Awaji Earthquake Disaster in Nishinomiya City, has been expanded with new data entries. The database contains the following very detailed datasets: (1) the urbanization area base map, (2) casualty data, (3) three sets of building damage data surveyed by the Nishinomiya City, the Architectural Institute of Japan and the City Planning Institute of Japan, and the Kobe University, (4) building property data based on the real estate tax roll, (5) photographs of the damaged buildings with the information on the place and orientation of the picture, and (6) the estimated distribution of the seismic ground motion. The seismic ground motion was simulated for the southern part of Nishinomiya City and two verification sites in Kobe City and Amagasaki City. In the simulation, the borehole data of public facilities were used to model the surface soils as one-dimensional layers, taking into consideration the fact that the spatial distribution of the sediment/basement interface forms a slope. The model of the fault rupture process simulated the characteristics of the seismic motion at basement level, and amplification effects of the surface layers were evaluated based on multiple reflection theory. The distribution of peak ground acceleration and peak ground velocity was estimated from acceleration response spectra at each borehole point. In addition, the relationship between simulated seismic ground motion and building damage was studied based on newly proposed band-passed spectrum intensity using the expanded database. This confirmed that detailed categorization is necessary in order to evaluate the fragility functions, especially for reinforced concrete structures. The database should provide fundamental information for identifying the relationship between the ground motions and the extent and pattern of building damage, or the pattern of the occurrence of casualties.

Access to Document (DOI)

Process of Housing Damage Assessment: The 1995 Hanshin-Awaji Earthquake Disaster Case

Horie, K., Maki, N., Kohiyama, M., Lu H., Tanaka, S, Hashitera, S., Shigekawa, K., and Hayashi, H.

Natural Hazards (Springer) 29 ( 3 ) 341-370 2003.07

Research paper (scientific journal), Joint Work, Accepted

Rebuilding of victims' livelihoods was a crucial issue in the restoration process in the1995 Hanshin-Awaji Earthquake Disaster. Housing damage assessment influenced most of the rebuilding of the livelihood in the long term, because the Victim Certificates issued by the local governments based on the results of the Housing damage assessment was required to receive most of the individual assistance measures. In the process of Housing damage assessment, many complex problems arose, leading to extensive work on the part of the disaster responders. Consequently, a considerable number of victims were dissatisfied with the assessment and applied for a resurvey. Due to a flood of requests for resurvey, disaster responders had to work on damage assessment, leaving relief activities aside. In order to facilitate Housing damage assessment, this paper discusses the following five points: (1) the processes and the problems of assessments performed in the Hanshin-Awaji Earthquake Disaster, (2) the changes in the nature of information needed by the victims, (3) the improvements over the present damage assessment, (4) the housing situation in Japan, and (5) the international situation on damage assessment. It is obvious from the results that a poor damage assessment system and the size of the disaster produced a very large work load. Differences in appreciation among the investigators also contributed to unfair assessments and led to the victims being increasingly dissatisfied by the survey results. Finally, a design concept for a comprehensive damage assessment system, which has been derived from the above five points, is proposed for post-disaster management.

Access to Document (DOI)

Building Damage and Casualties after an Earthquake: Relationship between Building Damage Pattern and Casualty Determined Using Housing Damage Photographs in the 1995 Hanshin-Awaji Earthquake Disaster

Lu H., Kohiyama, M., Horie, K., Maki, N., Hayashi, H., and Tanaka, S.

Natural Hazards (Springer) 29 ( 3 ) 387-403 2003.07

Research paper (scientific journal), Joint Work, Accepted

The relationship between building damage patterns and human casualties in Nishinomiya City - one of the most heavily damaged cities in the 1995 Hanshin-Awaji Earthquake Disaster - was investigated using photographs of damaged buildings. First, the photographs of buildings in which casualties occurred were identified, and the building damage patterns were judged based on the photographs considering the existence of survival space. Then the relationship between the building damage pattern and casualty occurrence, and the characteristics of casualty distribution, were investigated. The main findings were as follows: Most casualties occurred in relatively old two-story wooden buildings in which the ground floor completely collapsed without survival space; casualties occurred at all building damage levels including "no damage", and it can be seen that building damage is the major, but not the sole cause, of casualties in an earthquake; in Nishinomiya City, the regional distributions of casualties due to the collapse of buildings that left no survival space is similar to that of casualties due to other types of building damage.

Access to Document (DOI)

Evaluation of Seismic Diagnosis Methods for Wooden Housing Intended for Web Service

Kohiyama, M., Ujita, N., Murao, O., Kato, T., and Yamazaki, F.

7th U.S./Japan Workshop on Urban Earthquake Hazard Reduction 8 2003.03

Research paper (international conference proceedings), Joint Work

Recently, many private and public sectors have provided methods of seismic diagnosis for wooden housing on their Web pages. Since the Internet can easily gather a large number of participants, it is expected that these Web pages will promote house owners to recognize earthquake risks, to carry out the retrofit works, and to join to earthquake insurance. This paper proposes an effective and adequate method for seismic diagnosis of wooden houses through the Internet. First, a questionnaire was carried out to wooden-house owners in Tokyo with the simple diagnosis method that is widely adopted in Japan. Secondly, experts visited and inspected the houses by two methods: the simple method, and an in-depth more accurate method, which calculates eccentricity and story stiffness based on the wall materials and allocations. Finally, three diagnosis results were compared. The results revealed that the owners, who are non-experts, returned the diagnosis results diverging from that of experts while the results of the simple and the accurate methods by the experts matched fairly well. Thus, the simple method itself is effective, but in order to improve non-expert result, the followings are suggested: a) provide a land condition (geologic and geomorphologic) database, b) present sample photographs of foundation cracks to prompt them to check carefully before their diagnosis, c) indicate alternatives of wall length along with a house plan and consider a roof type, d) add the questionnaire entry on types of inner and outer walls, and e) add the questionnaire entries on the second-floor area and the center of gravity.

Understanding the Local Characteristics of Earthquake Risk Awareness of Residents in Sumida and Setagaya

Takaaki KATO, Mitutomo KOMIYA, Hiroaki KAMENO, Takuma SAEKI, Osamu MURAO, Fumio YAMAZAKI, and Masayuki KOHIYAMA

11th Japanese Conference on Earthquake Engineering 3 2423-2428 2002.11

Research paper (conference, symposium, etc.), Joint Work, Accepted

The purpose of this study is to investigate the structure of earthquake risk awareness of residents through analysis on a questionnaire survey in the two districts in Tokyo: Setagaya and Sumida, which are typical residential districts from the viewpoint of urban housing planning. Our study focuses on the relation of the risk awareness of residents and the actual risk of their house, and the preference of the alternative to reduce their risk. In this paper, we clarified the differences dependent on the local characteristics and the universality in these two districts to regard as important, in considering the measure for mitigation planning, earthquake insurance and retrofit of house, and abstracted some points to analyze on in detail in the following study.

Characteristics of Wooden Housing Damage Based on Damage Survey Data of Yonago City in the 2000 Tottori-ken Seibu Earthquak

Takashi KUMITA, Masayuki KOHIYAMA, and Fumio YAMAZAKI

Journal of Social Safety Science (Institute of Social Safety Science) ( 4 ) 135-142 2002.11

Research paper (scientific journal), Joint Work, Accepted

The wooden housing damage due to the 2000 Tottoriken Seibu Earthquake was analyzed using the damage survey data investigated by Yonago City. It was clarified that the actual housing damage ratios are lower than estimated results based on simulated peak ground velocity and fragility curves that were derived from the data of the 1995 Hyogo-ken Nanbu Earthquake. Damage mode, which is combination of roof, wall, and structure damage ratios and tilting levels, were calculated for each topographically classified area, and its regional trend was revealed.

Analysis on Regional Characteristics of Seismic Performance Indices of Wood-Frame Buildings Based on the Results of Seismic Capacity Evaluation in Yokohama and Himeji

Yuuki ISHIHARA, Masayuki KOHIYAMA, and Fumio YAMAZAKI

11th Japanese Conference on Earthquake Engineering 2 2091-2096 2002.11

Research paper (conference, symposium, etc.), Joint Work, Accepted

In the present methods to estimate buildings’ damage due to an earthquake, empirical fragility curves based on damage statistics are mostly employed. The structural type and construction period were considered in developing them, but regional characteristics were not considered well. The objective of this study is to analyze the results of seismic capacity evaluation conducted in two cities, Yokohama and Himeji, for more accurate damage estimation. From the analysis of the data, it is observed that there are significant differences in the seismic performance of the buildings in the two cities even though they have the similar structural type and construction period.

Analysis on Regional Characteristics of Seismic Performance Indices of Wood-Frame Buildings in Japan Based on the Results of Seismic Capacity Evaluation

Masayuki KOHIYAMA and Fumio YAMAZAKI

11th Japanese Conference on Earthquake Engineering 2 2097-2102 2002.11

Research paper (conference, symposium, etc.), Joint Work, Accepted

The regionality of seismic performance indices is analyzed based on the results of seismic capacity evaluation employed to buildings of all over Japan. The evaluation results are aggregated into eight regions: Tohoku, Kanto, Hokushinetsu, Chubu, Kansai, Sanyo, Shikoku, and Kyushu, considering culture and climate. The distributions of the construction year and total area of floor space are examined of their similarity to those of Housing and Land Survey taken by the Statistics Bureau of Japan. Buildings in Tohoku show the lowest performance indices in eccentricity, but the highest in horizontal resistance. The ratio of buildings with construction year older than 1981 and area less than 50 m2 should be adjusted to that of the survey result because they have poor performance indices.

Seismic Observation System for a Building and Surrounding Ground in Komaba Research Campus of the University of Tokyo

Calle, G. D., Kohiyama, M., and Yamazaki, F.

7th U.S. National Conference on Earthquake Engineering 10 2002.07

Research paper (international conference proceedings), Joint Work

Recently, the Institute of Industrial Science of the University of Tokyo has been moved from Roppongi Campus to Komaba Research Campus. In the relocation, seismic observation system was newly set up in the institute's building, on the ground surface, and in a borehole. The observation system has collected the records from six seismic events. On the basis of these records, site and building responses were analyzed. The results showed general characteristics of the seismic response in the urban center of Tokyo, particularly, the site amplification due to sediments over Tokyo Formation. A particular soil anisotropy was found around 4.2 Hz due to the soil-structure interaction. In the future, more observation records will be collected and it is expected that the data may provide the details of the site and building response characteristics.

Detection of Damage Due to the 2001 El Salvador Earthquake Using Landsat Images

Estrada, M., Kohiyama, M., Matsuoka, M., and Yamazaki, F.

22nd Asian Conference on Remote Sensing 2 1372-1377 2001.11

Research paper (international conference proceedings), Joint Work

A strong earthquake hit El Salvador on January 13, 2001. The earthquake with a magnitude of 7.6 caused huge damage in the urbanized areas as well as numerous landslides. In case of large scale earthquakes, the identification of hard hit areas is important and necessary information for decision-makers to handle the disaster relief process. In this study, remote sensing images taken before and after the earthquake by Landsat 7 (ETM+) satellite are compared to identify the location of landslides and hard hit urban areas. The proposed method uses the rationing between bands in the visible range as well as the sharpening of the multi-spectral bands by merging with the panchromatic band. It is expected that with the help of this additional band the identification of landslides and damaged areas will be improved.

Time-Series Images Method for the Improvement of Estimation Accuracy of Early Damaged Area Estimation System (EDES) Using DMSP/OLS Nighttime Imagery

Masayuki KOHIYAMA, Haruo HAYASHI, Norio MAKI, Mitsuhiro HIGASHIDA, Herbert W. KROEHL, Christopher D. ELVIDGE and V. Ruth HOBSON

Journal of Social Safety Science (Institute of Social Safety Science) ( 3 ) 173-180 2001.11

Research paper (scientific journal), Joint Work, Accepted

The new method is proposed to estimate damaged areas using the Defense Meteorological Satellite Program's Operational Linescan System (DMSP/OLS) nighttime imagery for the Early Damaged Area Estimation System (EDES). The former method uses two-acquisition-date images of pre- and post-events, but it has problems of weakness for cloud influence, misdetection of damaged areas due to water reflection of city lights, and tendency to neglect damages in small towns. To address these problems, the proposed method employs significant tests on a pixel basis based on each pixel's average and standard deviation, which are evaluated from time-series images during gain stable periods around new moon phases.

Resolution Improvement of Frequently Observed Satellite Imagery for Urban Characterization

Kohiyama, M. and Yamazaki, F.

22nd Asian Conference on Remote Sensing 1 158-163 2001.11

Research paper (international conference proceedings), Joint Work

This paper proposes the method to develop a high-resolution image of urban properties from frequently observed low-resolution images based on the statistic process assuming urban properties have little temporal change. Because disaster responders sometimes have difficulty to obtain the map data in a digital form especially in developing countries, it is well known that satellite imagery and aerial photographs can support disaster response and rescue activities. But high-resolution images that can provide roads and buildings information expense considerably high when acquiring wide range data by means of aerial photographs or imagery of recently launched satellites with high-resolution sensors. On the other hand, satellite images of spatial resolution of 10 to 100 meter order cost comparatively low. The paper discusses the number of low-resolution images to develop a high-resolution image. First, a one-meter-resolution image derived from an aerial photograph is used as a truth image. Three-meter-resolution image is also evaluated as a reference high-resolution image. Secondly, a nine-meter-resolution image, which simulates an image scanned by a low-resolution sensor of satellites, is evaluated with a randomly selected offset of scan line. The same cell size as a reference image, i.e. three meter is employed for the low-resolution images. Thirdly, a resolution-improved image is synthesized from the average and standard deviation based on each pixel calculation of the simulated images. Then the difference between the reference image and synthesized image is evaluated. Finally, the relationship between the number of low-resolution images and the standard deviation of differences of all pixels in the average image is analyzed. The result quantitatively clarifies that a high-resolution image of urban properties with little temporal change can be developed with a sufficient number of low-resolution images when the precise geolocation is guaranteed.

Automatic Detection of Building Properties from Aerial Photographs Using Color and 3D Configuration

Kokubu, K., Kohiyama, M., Umemura, K., and Yamazaki, F.

22nd Asian Conference on Remote Sensing 2 1197-1202 2001.11

Research paper (international conference proceedings), Joint Work

The buildings properties in spatial databases are very useful for urban planning, disaster mitigation, insurance business etc. But the databases in some governments are not freely available since they include private information. Therefore, the data acquisition mostly depends on image interpretation of photographs and field surveys. Consequently it is time-and labor-consuming and very costly to construct databases, and it is not easy to maintain the data up-to-date and to employ them in wide use. In this study, automatic detection method of building properties based on aerial photographs is proposed and the result is verified by the database made in a conventional way of data acquisition. The method consists of the following steps: (1) geometric correction and gray scale conversion of aerial photographs, (2) stereo matching and evaluation of building heights, (3) evaluation of building areas, (4) color and texture analysis, and (5) classification of buildings. Buildings are classified into the following categories: (a) detached houses, apartment buildings and multi-storied buildings. (b) wooden and non-wooden buildings. The method is applied for a target area in Tokyo and the result is compared with the ground truth data investigated by the authors and the database provided by of Tokyo Metropolitan Government. As a result, it is found that low-storied apartment buildings and multi-storied buildings are correctly identified and they can be classified into proper structural types.

Framework for Damage Assessment Training System

Horie, K., Maki, N., Hayashi, H., Kohiyama, M., Shigekawa, K., and Tanaka, S.

8th International Conference on Structural Safety and Reliability (International Association for Structural Safety and Reliability) 8 2001.06

Research paper (international conference proceedings), Joint Work, Accepted

Damage Assessment Training System (DATS), which consists of an effective damage assessment system and a training system for its use, is proposed to enhance awareness and skills of disaster responders. DATS is designed based on the analysis of building damage assessment performed following the 1995 Hanshin-Awaji Earthquake Disaster. It integrates several improvements over the building damage assessment methods currently in place, and should provide information on housing damages in a much more timely fashion. It is aimed at expediting the work involved in disaster response, therefore, disaster responders would be relieved from the extensive work of damage assessment and should be able to devote themselves to higher-quality service for livelihood rebuilding of victims.

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