The non-engineered housings of RC frame with masonry wall structure have serious problems. One of them is that they must collapse due to destructive earthquakes which will take place in future. We tried to make clear of their dynamic parameter properties, related to the seismic design and the earthquake damage. First, the fundamental natural frequency/period was obtained based on the microtremor observation results and the damping ratio on the artificial force-vibration tests. The restoring force models are assumed based on the static lateral force tests and they are introduced into the dynamic earthquake response analysis. Last the analytical results are discussed considering the earthquake damage and disaster.

We have learned many problems by the 1995 Hanshin Awaji earthquake. The chief cause damage was collapsed a houses. Most of the death toll accompanied collapsed houses by earthquake. This study aims at estimation anticipating risk of collapsed house. Discussion is needed in relation with earthquake resistant diagnosis score. If lower is the necessary earthquake resistant diagnosis score then reduction in resource quantity comes. Therefore, analyze change about resource quantity. On the basis of risk estimation, a comparison between the present condition and analysis result by a study was made. And we developed feasible method for the death toll reduction.

To understand and evaluate structural characteristics of typical traditional wood houses in Kyoto, structural styles and details of thirty traditional wood houses were investigated. The wooden frames, seismic structural elements and joints are clarified. From investigation results, it is found that these wood houses have significantly different base shear coefficients in the directions; in particular, the base shear coefficients in the ridge direction are low. From the seismic performance analyses, it is suggested that the seismic reinforcement is needed for many traditional wood houses.

The paper demonstrates a series of vibration experiment education materials called ‘BURURU' which have been developed for the enlightenment of disaster prevention consciousness in the society and for the education of structural dynamics in University. These are composed of hand rotating type whchi is a handy shaking table box, the electric powered version electric powered type, the small shaker type used for the harmonic excitation on the model, the hand cart type which uses a hand cart as shaking table, the electric hand cart type controlled by arbitrary input waves, the wooden house collapse model showing the difference of collapse due to seismic retrofit, and the paper house model which is a paper craft.

Recent damaging earthquakes have clearly revealed that retrofitting low earthquake-resistant structures is the key issue for earthquake disaster reduction. The authors have proposed a new Retrofitting Promotion System (RPS) as driving forces for the promotion of retrofitting of weaker structures. The main concept of the RPS is that the government guarantees a portion of the building repair and reconstruction expenses if retrofitting is implemented by the owner following the guidelines before the earthquake and in spite of this, the structure is damaged. A questionnaire survey was conducted for homeowners in the Kanto region with respect to their attitude to the proposed RPS. Based on a result, the effectiveness of RPS was verified.

As for the fire rate (the number of fire matters of the population of around 10000 people) by all the prefectures in 2003, maximums were 6.9 of Yamanashi Prefecture, and minima were 2.8 of Toyama Prefecture as to it. And, as for Tokyo as well, a big gap is formed in the fire rate by the ward cities by the area. The fact like this makes it guess that the occurrence of the fire is influenced by the character of that area. This research explained the character of the area concerned with the fire occurrence by multiple regression analysis, principal component analysis. And, this result contributes to the foundation materials of the firepower arrangement, the improvement in the fire prevention, regional disaster preparedness, and so on.

The Niigata Chuetsu Earthquake with a magnitude of 6.8 shook the Chuetsu region of Niigata prefecture on October 23rd, 2004. In order to quickly grasp the overall situation of damages, various governmental organizations conducted structural damage assessments by utlilizing a great number of personnels soon after the earthquake occurred. Our research team supported this damage assessment by developing a proto-type of GIS application with mobile device at Odiya city . Though this experience, we were able to develop a versatile GIS application for field data entry called “Authoring System,“ and build a field survey support system (POS), which involves a comprehenvive information processing for post-disaster field survey.

To cancel the fault for the disaster that occurs in recent years, a standard system for the disaster response of Japan was examined referring to Incident Command System (ICS) that was a standard system for the disaster of the United States. ICS Forms is used in ICS for a disaster response. The focus was appropriated to those Forms, and Japanese version ICS Forms was examined. When examining it, the idea of the project management was used. As a result, necessary information for Japanese version ICS Forms was able to be classified. The examination will be recommended in the future, a suitable ICS Forms for Japan is examined further more.

Japanese Emergency managers struggled to install Incident Command System concept into Japanese emergency management system. It is because emergency managers need emergency management system which enables coordination among various levels of governments, and works at any types of emergency. In ICS system, emergency operation center and information processing system is a key facility and system in emergency management and concept of ICS is strongly reflected into design of those facilities and systems. In this paper, issues on installing ICS into Japan from the analysis of present status on EOC and Information processing system in Japanese government and large cites.

Monument construction was proposed as a new index on community recovery from the Hanshin-Awaji earthquake disaster. Three facilitating and two suppressing factors of monument construction were identified by using GIS and multiple regression analysis method. Three facilitating factors were that there was earthquake caused death, evacuation shelters and urban redeveloped. Two suppressing factors were that there was urban redevelopment where was earthquake caused death and temporary housing. The clue of community recovery can be obtained by paying attention to whether monument was constructed or not.

The purpose of this study was to earthquake disaster reduction by resolving information issue in the recovery service for municipality. In this study, the support for recovery service was conducted at the municipality in the disaster area of the Niigata-ken Chuetsu earthquake. Latent information problem was given from support activity at the actual operation. Spatial Temporal information system was presented as a problem solving method, and then the practice support to achieve the presented information processing was developed. The effectiveness of this system was used and validated at the municipality.

This study evaluates the information sharing method powerd by GIS technology following a Mw.6.8 earthquake on the middle area of Niigata (Chuetsu area) on 23rd October 2004. We established the Chuetsu Earthquake restoration and revival support GIS project. Many kinds of data about the damage situation that the government and local governments or associated organizations owned were unified by GIS technology, and it was shown as a portal site on the Internet. The data input process was done outside the damaged area. These data were offered to the damaged area, and only practical use was expected. The effectiveness was shown as one of the methods of restoration and revival support by activity of the project.

Incident Command System (ICS) has been proved to be effective as the de facto global standard for crisis management in advanced countries. Japan is an only exception. In this paper, we investigated how Emergency Operation Center (EOC) of Ojiya City processed the information at the time of the 2004 Niigata-ken Chuetsu Earthquake Disaster for the first 100 days since October 23, the very first day, to Feburary 1. During this period, Ojiya City EOC has processed a total of 3,000 information. A content analysis for this information was performed focusing on theme, time, and geo-location to create a database on which we evaluated the information processes adopted at Ojiya city EOC by applying the information processing procedure proposed by ICS. We found that the main function of Ojiya City EOC was quite consistent with ICS, planning and logistics management.

This paper presents the Ojiya City disaster management support project that was done for the 2004 Mid-Niigataearthquake disaster. The objective of the project is to support the post-disaster management operations such as housing damage assessment, damage database development, and damage certificate issuance. This project developedthree systems; 1) standard procedure of the housing damage assessment, 2) standard method for developing the victim database, and 3) standard system for issuing the victim certification.

An applicability of Damage Assessment Training System (DATS), which has been developed from analysis of the lessons of the 1995 Hanshi-Awaji earthquake disaster in order to support a work involved in building damage assessment for issuing Victim Certificate, was verified through an actual operation by disaster responders at Ojiya city following the 2004 Niigata-ken Chuetsu earthquake. As a result, it was clarified that a high performance of DATS was confirmed from the respects of time and accuracy. On the other hand, the DATS encountered some emerging issues, such as a daily training for newly appointed investigators by turns caused extensive load. To solve such situation, a prototype of computer software to achieve more efficient training system was also developed.

Building damage assessments for issuing victim certificate have significant roles for disaster victims in Japan, because the victim certificate issued by the local government based on the extent of each victim's housing damage grade was required to receive most of the individual assistance measures. This paper summarizes the process of building damage assessments conducted in the Niigata-ken Chuetsu earthquake, and identifies issues and propose the direction to solve basical issues of Building Damage Assessment on system.

The purpose of this research is to develop a Damage Certificate Issuing Support System for maximizing the efficiency of the services cities must provide to citizens in response to a disaster. The system development work we did to support Ojiya City in the Niigata Chuetsu Earthquake was used as a case study to conduct this research. The objective was to build a GIS/database system to improve the efficiency of the city's services and to reduce the burden of the city workers, while providing satisfactory services to disaster victims. Additionally, the research aimed at building a centralized victims' database that can be used and developed throughout the city in the long run to support various relief activities.

We examined the effectiveness of Service Management Framework in designing counter operations in disaster victim support through the hands-on support activity for Ojiya city’s victim certification after Niigata-ken Chuetsu Earthquake, Oct. 23, 2004. The service package and the Service Delivery System for the counter operation of victim certificate issuance was designed and implemented on the basis of Service Management Framework. As a result of customer satisfaction survey on Ojiya city and Kawaguchi town, a neighbouring town also affected in the event, it was clarified that the counter operation of Ojiya city was evaluated higher in terms of simplicity of the procedure by the victims than that of Kawaguchi town.

The random sampled survey was designed to clarify the disaster process of victims in the 2004 Mid-Niigata Prefecture Earthquake. The findings of the survey were as follows: 1)About 70% of the respondents escaped to the outside of their home staying in cars, tents and garages on the day of the impact because of the terror of the aftershocks, 2) Almost 100% of the respondents tried to confirm the safety of somebody or/and something right after the impact, 3)According to the ‘Reconstruction Calendar,' the majority of the victims thought their offices/schools had resumed, and the financial situation of households were getting better, while other items about housing, daily life had not been restored yet.

The purpose of this study is to draw allocation planning policy of temporary houses from analyses of victim's satisfaction after Niigata-Chuetsu Earthquake. The results are as follows; 1) "local community continuity" and "consciousness to facilities of their temporary housing" are extracted as appropriate variables to affect the victim's satisfaction by structural equation modeling. 2) In addition, it is clarified that sift arrangement by original local settlements can not be always continue the local community because many young households do not join local community. 3) It is concluded that new allocation methods that can arrange various resident needs is required.

Not only disaster damage but also recovery process are different in each disaster. On the 2004 Mid Niigata Earthquake (Mw6.6), there are some characteristic issues in the response and recovery processes of follows; (1)Various spaces and facilities such as public facilities, private yards, private cars, semi-private open spaces were used as evaluation space. (2)Snow influenced recovery activities and speeds, because Niigata is heavy snow region in Japan. The Response and recovery process for a half-year after the earthquake in Kawaguchi-town was surveyed. Land-use for post-disaster activities was observed intermittently and, characteristics of recovery process in Kwaguchi-town were considered.

The Emergency Fire Response Team is fire brigades that concentrate from the whole country at a large-scale disaster, and execute the fire fighting activity in the stricken area. It is necessary to grasp the number of the required fire brigades corresponding to the scale of disaster for the effective operation strategy, because there is a limit in the number of fire brigades. By this research, various experiments were conducted ,and the elucidation of quantitive grasp and an effective operation strategy was performed about the employment of an Urgent Fire Support Team.

On July 13,2004 in Niigata Prefecture 15 people have been killed due to the disaster caused by a severe rain. 12 of them were classified as "elderly" people who were over 65 years old. We investigated using profiling technique the causes of why the 12 persons who have been killed by the flooding disasters based on the integration of various kinds of related information through GIS. 3 distinct patterns were identified; 1) It was caused by a severe flooding which exceeded 3 meters high and collapsed the wooden houses where the victims were located, 2) It was caused by strolling in the flooding situation, 3) It was caused by the individual vulnerabilities such as over 75 years old, need for assistance due to difficulty in walking capability, and the unavailability of assistance at the time of flooding.

Disaster victims of Fukui Downpour received better support by local government, compare to the previous other disasters. The study though reveals facts that victims suffer for wider range of damage than what the government publish. It is necessary to find demanded schemes for theses victims by evaluating their process of housing recovery. A platform for volunteers were established by a NPOs' network with cooperative effort of local government. The study also finds out that voluntary support have encouraged residents to start repairing the houses, while local government support is rather limited.

Two researches were conducted to clarify the disaster process of the elderys in the Niigata Flood and Mid-Niigata Prefecture Earthquake. The major findings were as follows: 1. the care managers as fhe professionals licenced by the government-sponsored Long-Term Care Insurance System worked effectively to manage the needs of moving temporarily to care facilities, 2. 51 elderys still stayed in the care facilities, while victims in the impacted area had begun to consruct their lives in the region, 3. the numbers of people who took in-home services decreased month after the inpact, while the numbers of victims who took in-facilities services increased. The disaster care management system needs to be established for responding to the eldery's special needs in disasters.

Collapse mechanism of graves due to earthquake was investigated using 3-D DEM. Five Japense-type and five European-type graves with different width-height-ratios were analyzed. Acceleration record obverved in 1995 Hyogoken nanbu earthquake was used as input ground motions changing its peak ground acceleration from 100gal to 1000gal. Compared with Japanese-type, European-type graves are found to have higher earthquake-resistance. Collapse mechanism of Japanese-type graves is rocking collapse, where the width-height ratio is dominant. Graves with smaller width-height-ratio have higher earthquake-resistance. Collapse mechanism of European-type graves is sliding collapse where the width-height-ratio is not critical. We should take measures to prevent grave stones from falling down.

In recent years, after an earthquake, strong motion records are offered on many internet sites. This paper constructs the computer system which estimates the ground motion distribution utilizing these records. Because this makes estimated distribution of ground motion closer to real distribution, it can be expected to improve the precision of damage estimation. This paper also presents the estimation method to avoid influence of vacancy of observation near epicenter and to shorten calculation time of spatial interpolation.

In order to propose an empirical method for estimating Japan Meteorological Agency instrumental seismic intensity from ground motion parameters, the strong motion records during recent major earthquakes, e.g., the 2000 Tottori-ken Seibu earthquake and the 2004 Niigata-ken Chuetsu earthquake, are compiled. Using the strong motion data including relatively large number of records with high intensity level, the relationships between instrumental seismic intensity and three ground motion parameters, i.e., peak ground acceleration (PGA), peak ground velocity (PGV) and the product of PGA and PGV, are examined. Results indicate that an empirical method for estimating the instrumental seismic intensity from the parameters would predict the seismic intensity with reasonable accuracy in high intensity range.

The purpose of this study is to clear the relationship between rainfall factors and geomorphological factors to predict slope failure and prevent landslide disasters during heavy rainfall. In this study, risk of slope failure caused by geomorphological factors is evaluated statistically using existing inspection records for steep slopes through the application of Quantification Theory Type 2. Moreover, rainfall factors are analyzed to determine the critical rainfall line. Conventional liner Critical Line and Soil Water Index calculated by Tank Model are under consideration, in this research. This paper shows that high risk areas are prone to landslides with little rain. The results of these analyses will specify and predict areas prone to collapse for warning and evacuation procedures.

The damage of road bridges by severe earthquakes gives a large influence on the activities of saving lives and the restoration from the earthquake disaster. Therefore, it is very useful to estimate beforehand the damage degree of road bridges by earthquakes in order to devise the strategy to the earthquake disaster in the city. The objective of this study is to establish the prediction of earthquake damage of road bridges by using the investigation result of the damage degree of road bridges by the earthquakes in the past, in which the Quantification Method Ⅱ is used to construct the prediction.

One of the obstruction to reinforcement work for earthquake-resistant of wooden houses is unclear efficacy on the cost. To clarify the cost performance of the reinforcement work for wooden housing, the authers obtained actual construction data-sets cooperated with Japan wooden housing earthquake-proof reinforcing businesses cooperative and a construction company. Based on the data-sets and interviews, this paper presents 1) problems related to the government grants from the viewpoints of local governments, construction companies, and residents, 2) the actual situation and contents of the reinforcement work in Japan, 3) the relationship between the cost and improvement on its earthquake-resistant capacity, and 4) suggestions how the reinforcement work in Japan should be done.

Fireworks display was held at Akashi City, Hyogo on July 21, 2001. In the passageway to the exhibition site, many pedestrians were involved in a crowd accident. The contact force acting between the pedestrians might cause the awful accident. In past researches, a human body is modeled as a distinct element and the force act on the body are calculated by use of the Distinct Element Method (DEM), however, the calculated force has not been verified through an observation or an experiment. In this study, experiments were done to measure the contact force acting on the human body in a crowd. The forces calculated by use of elliptic distinct element were in good agreement with the experimental results

In order to promote aseismic retrofit and to mitigate earthquake damage, it is necessary for inhabitants to recognize the seismic risk of their own houses. This paper presents a method for damage prediction of a wooden house based on the results of seismic capacity evaluation and strong motion evaluation. The method is developed so as to simulate the wooden house damage in recent earthquakes, the 2000 Western Tottori prefecture earthquake and 2001 Geiyo earthquake, in Japan. Finally, we confirm the effect of aseismic retrofit on seismic damage mitigation from predicting seismic damage of wooden houses by the proposed method.

Seismic hazard is real threat in most part of Japan. Although 12.2% of housing stock in Japan is vacant and the rate has been increasing, transactions in housing market for existing dwellings are much lower than those in the United States. Proper reuse and retrofit of existing timber frame dwellings are important to mitigate urban seismic risk and to reduce C02 emission. Besides, current students need more flexibility to choose the places to live and to move where job opportunity is available. Therefore they certainly require basic knowledge and skills to choose safer locations and qualified dwellings, and to manage financial risk. This paper proposes the contents of a lecture to hand out students those basic skills, examines their responses, and discusses ways for further improvement.

A methodology to extract slope failure susceptible areas in an urban areas using high-resolution digital elevation model (DEM) is proposed in this study. The criteria for the gradient of slopes, the slope height, the distance from slopes to buildings, and the slope area are included in the topographic analysis. The method is applied to the DEM and the GIS building data in Yokohama city to extract the slopes that satisfy the criteria. The result agrees with the existing map of the slope failure susceptible areas. The effect of the resolutions of DEM on the extraction is examined. The results for the DEM with the resolution of 1m or 2m show better agreement with the ground survey than that of 5m.

Many oil refineries and storage tanks are constructed in the coastal region in Japan. So once an earthquake occurs, there are risks that not only oil spill and a fire, but also tsunami damages. To reduce damages caused by tsunami, it is important to evaluate the safety of these important structures for tsunami. In this study, we clarified characteristics of tsunami runup on shore and tsunami wave force for oil storage tanks through the hydraulic model test and considered the predictive method for tsunami damages.

A large earthquake of magnitude 9.0 on Richter scale occurred off the Sumatra Island caused enormous tsunami damage in Indian Ocean. It is said that the absence of early warning system in Indian Ocean like in the Pacific Ocean and lack of the knowledge about tsunami caused such damage. However, the later one is not demonstrated by the definite sources in the present circumstances. Based on the so called reason mentioned above, a questionnaire survey on tsunami awareness was carried in Sri Lanka on the scale of 2,500 samples. The results reveal that the current situation and community's capacity to respond to natural disasters are obtained.

A questionnaire survey about the disaster waste for local governments where the Disaster Relief Act due to the flood disaster after 1999 had been applied was carried out, and the per unit generation waste was estimated. The per unit generation waste of flood damage above the floor level was estimated 4.6 tons per a household and the per unit generation waste of inundation damage below the floor level per a household was estimated 0.62 tons. The procedure to estimate weight of disaster waste due to flood disaster considering the number of house damages was presented. As a result, it was showed that the relative quantity of disaster waste could be available to assistance for emergency responses of public authorities on flood disaster.

Arson is seemed to be connected with some characteristics in urbanized environment because the number of arson is increasing in urban area although the total number of fires has been decreasing. Then, we investigate the occurrence situation of arson and find their deterrent factors in order to find effective measures against arson in Mukojima area in Tokyo from town management point of view. We examine physical environments and local community's activities and some tendencies are revealed as follows; (1) Arson occurs in unnoted area and accessible area, (2) Arson is prevented in area where local community is well-organized and activities are well-practiced.

A LPG leak accident occurred at a plant in Higashinada ward, Kobe city, due to the Hyogo-ken Nanbu Earthquake of 1995. In order to make sure residents' safety, Kobe municipal authorities issued evacuation counsel to 72,000 people around the plant on 18 January, 1995. Two years later, a questionnaire on the residents was conducted to grasp the situation of the communication of the counsel and the residents' evacuation. The results of the questionnaire are as follows; 89 percent of respondents got to know the evacuation counsel on that day, and 78 percent among them executed to evacuate caused by the accident.

When a strong earthquake hits a city, a number of fires may occur at the same time and the city would suffer huge damage by spreading fire. Therefore, it is very important for fire departments to grasp information of fire outbreaks actively and make fire fighting effective. In this study, we develop a simulation system that estimates the effects of gasping information by fire fighters immediately after an earthquake. From the simulation results, grasping information by firefighter proves helpful in finding fires in early stage of fire spread and decreasing fire damages. Then we reveal possibility that early grasping fire outbreak shifts paradigm of fire fighting strategy.

In this study, I presented the optimization methods concerning the allocation of fire stations and fire engines, and developed them as an application software for a personal computer. For the allocation of fire stations, using the ratio of fires that fire pumpers were able to reach within a fixed time as an objective function, I obtained two results of optimum allocation by mathematical programming and hill-climbing method. And, I confirmed that there was little difference between the two . Hill-climbing method is good for programming easily, and widely applicable to nonlinear problems, though this is a local optimization method. Additionally, I presented the unified optimum methods for the allocation of five kinds of main fire engines by the same idea as the case of fire stations.

After the Hanshin-Awaji great earth quake, the problem that the government should compensate for personal property is causing debate. The Japanese government has refused to compensate for personal property from the era of Meiji. However, the idea that the government should compensate for personal houses is becoming popular, and some local governments make virtual compensation. On the basis of these situations, firstly we will first explain the recent moves in personal compensation, and then will think of the constitutional rationale and financial reasons which make compensation for personal properties difficult. Furthermore, after presenting the current situation in America, we would like to propose a new assistance system in Japan.

The purpose of this research is that it clarifies the Great Hanshin-Awaji Earthquake victim's life recovery through panel data(N=364). The influence level that the respondent's information(attribute,house damage etc) gave to the life recovery feeling at the time of 2003 was examined.It was clarified that certain patterns were in the factor group that provided for the victim's life recovery eight years from the following result; two factor groups that life recovery feeling is predictable was derived in 1) 2001 (civic mindedness, civic engagement, mental and physical stress,2001job*house damage), 2) 2003(income, family cohesion).

Considering immense damage by great earthquake, pre-disaster planning for post-disaster recovery is vital for the disasterresillent community. From this point of view, we designed neighborhood community-training program for post-disaster recovery applied of the participation method for community-based development (Machidukuri). Our team were involved to develop and manage one program held in Shinkoiwa (Katsushika ward, Tokyo) during November 2004 to April 2005. In this paper, backgrounds of target neighborhood community and implemented program were explained. After that, questionnaire survey to participants who contained residents, civil servants and practitioners was analyzed to measure the impact of this program. Finally, a position of the program among disaster reduction policies were discussed.

This paper reviews existing literature that have focused on the Local Plan for Disaster Prevention in terms from public administrative planning. The local disaster management policy has several problems that attribute to the complexity, hierarchical inflexibility, and dualistic context of the plan. Hence some local governments challenges to the current disaster policy scheme, by formulating the strategic plan called ‘Action Program' for earthquake disaster reduction.

The"disaster relief volunteer center"has been established as a new support system for disaster victim by volunteers. One of the most important issues to consider when running a disaster relief volunteer center is how to help people who have greater needs - the eldery and disabled, for instance. Those people may require more assistance than the government can provide. This paper examined the potentiality and the task of the new support system from the case study of the disaster relief volunteer center of Nakanoshima-cho established after the July 2004 Niigata heavy rain disaster. As a result,it turned out that investigation of the support demand by community based organizations worked effectively in the process of the adjustment of volunteers'supply and demand.

Recovery of local economy is one of the most important issues after natural disasters in rural area. We studied two local industries suffered from flood disaster in 2004, luggage industry in Toyooka-city and lacquer craft industry in Sabae-city. First, we figure out how local industries recovered from the disaster, especially focused on the activites by local companies in both cities. Second, we present expected local government role indispenasable for recovery of local indutries after natural disasters.

This article reviews the outline of the system of programs of emergency management in USA.Training of the U.S. has many examples currently performed combining the program of state and EMI, and the contents are crossed to polysemy.Some programs are carried out in two or more states.Communalization of the contents of training about crisis management is imagined.Moreover, there is a hierarchy of the program on condition of a specific program. However, this hierarchy is restricted to subjects, such as ICS and Hazardous Materials.

The Simulation Training of Earthquake Shelter Program (STEP ver 0.5) was developed, and the educational effectiveness of this program was examined. STEP presents to participant groups fictional situations such as "a strong earthquake convulsed the whole city, and you have been evacuated to the elementary school", and asks them to discuss what appropriate behavior the leaders of the shelter should take. Sixty-nine undergraduates, and 12 residents in Kobe participated in the simulation. The results indicated that STEP would be effective in education for disaster prevention.