5:15 PM - 6:45 PM
[HDS09-P02] Utilization of Various Nankai Trough Earthquake Occurrence Scenarios in Drills -Osaka Prefecture Council of Social Welfare
Keywords:Nankai Trough, Earthquake, Occurrence Scenarios, Diversity, uncertainty, Council of Social Welfare
1. Introduction
We are developing an earthquake disaster prevention simulator that can provide information on earthquake and tsunami hazards and the risks posed by such hazards, considering the time evolution after the occurrence of "unusual phenomena" as an example of the spatiotemporal diversity of earthquake occurrence. Until now, disaster prevention measures taken by companies have tended to avoid assuming earthquake scenarios other than the largest class. However, with the release of "Temporary Information on Nankai Trough Earthquakes," it is becoming increasingly important to assume a variety of earthquake scenarios when considering countermeasures. Therefore, following on from last year's study (FY2022), we have conducted a study to identify methods of utilizing occurrence scenario information generated from research into understanding and predicting Nankai Trough earthquake activity, as well as to identify issues. The Osaka Prefecture Council of Social Welfare, which is responsible for the operation of the Disaster Relief Volunteer Center and the care of welfare facilities, was provided with diverse earthquake scenarios as basic information on the occurrence of disasters, and conducted a disaster drill on January 26, 2024.
2. Extraction of occurrence scenarios
Various scenarios of earthquake occurrence are possible. In this case, an epicenter set was created based on the assumption that Osaka Prefecture would be severely damaged and that a certain amount In this study, diverse earthquake scenarios are represented by a combination of one or more epicenter areas (referred to as "epicenter area sets"). Since the number of combinations is large, we have selected a set of epicenter regions that assumes a case of severe damage in Osaka Prefecture and a certain degree of damage in a wide area.
1) Select the source region set with the highest probabilistic tsunami hazard weight and the impact-oriented source region set.
2) Extract intermediate cases of 1) above
3) The cases to be used were discussed at a stakeholders' meeting in Osaka Prefecture, and the use scenario was finalized.
The result was an intermediate case of 2). The earthquake ground motions and tsunami inundation depths in the affected areas were generated on a 250m mesh as assumed information, and the estimated results of building and human damage were also listed and used as basic information for disaster prevention drills.
3. Verification of information utilization methods and identification of issues
The disaster drill was conducted using a WebGIS map showing earthquake ground motion and tsunami inundation depth on a large screen at the headquarters and online at each block site, so that each participant could share a common understanding of the damage situation. Assuming that extensive damage had occurred in Osaka Prefecture, the opening and operation of the Disaster Volunteer Center was verified, and the response to damage to related welfare facilities was discussed.
As a result, we were able to plan and conduct drills more realistically than before by using diverse earthquake scenarios with scientifically supported data, and by using a case that focused on severe damage in Osaka Prefecture, which is different from the maximum size scenario. One of the challenges was that support from neighboring prefectures, which, like Osaka Prefecture, would be affected by the disaster, could not be expected, and it was unclear whether support could be expected in areas where subsequent earthquakes would occur. In addition, it was found that the lack of efforts to resolve the issue of whether it is possible to prepare not only for one scenario but also for multiple and diverse scenarios simultaneously, considering uncertainty, is an issue for the future. It was reaffirmed that, in reality, there are limitations in terms of cost, manpower, etc., and that organizational managers are required to make realistic decisions on what to select by setting priorities within that context.
We are developing an earthquake disaster prevention simulator that can provide information on earthquake and tsunami hazards and the risks posed by such hazards, considering the time evolution after the occurrence of "unusual phenomena" as an example of the spatiotemporal diversity of earthquake occurrence. Until now, disaster prevention measures taken by companies have tended to avoid assuming earthquake scenarios other than the largest class. However, with the release of "Temporary Information on Nankai Trough Earthquakes," it is becoming increasingly important to assume a variety of earthquake scenarios when considering countermeasures. Therefore, following on from last year's study (FY2022), we have conducted a study to identify methods of utilizing occurrence scenario information generated from research into understanding and predicting Nankai Trough earthquake activity, as well as to identify issues. The Osaka Prefecture Council of Social Welfare, which is responsible for the operation of the Disaster Relief Volunteer Center and the care of welfare facilities, was provided with diverse earthquake scenarios as basic information on the occurrence of disasters, and conducted a disaster drill on January 26, 2024.
2. Extraction of occurrence scenarios
Various scenarios of earthquake occurrence are possible. In this case, an epicenter set was created based on the assumption that Osaka Prefecture would be severely damaged and that a certain amount In this study, diverse earthquake scenarios are represented by a combination of one or more epicenter areas (referred to as "epicenter area sets"). Since the number of combinations is large, we have selected a set of epicenter regions that assumes a case of severe damage in Osaka Prefecture and a certain degree of damage in a wide area.
1) Select the source region set with the highest probabilistic tsunami hazard weight and the impact-oriented source region set.
2) Extract intermediate cases of 1) above
3) The cases to be used were discussed at a stakeholders' meeting in Osaka Prefecture, and the use scenario was finalized.
The result was an intermediate case of 2). The earthquake ground motions and tsunami inundation depths in the affected areas were generated on a 250m mesh as assumed information, and the estimated results of building and human damage were also listed and used as basic information for disaster prevention drills.
3. Verification of information utilization methods and identification of issues
The disaster drill was conducted using a WebGIS map showing earthquake ground motion and tsunami inundation depth on a large screen at the headquarters and online at each block site, so that each participant could share a common understanding of the damage situation. Assuming that extensive damage had occurred in Osaka Prefecture, the opening and operation of the Disaster Volunteer Center was verified, and the response to damage to related welfare facilities was discussed.
As a result, we were able to plan and conduct drills more realistically than before by using diverse earthquake scenarios with scientifically supported data, and by using a case that focused on severe damage in Osaka Prefecture, which is different from the maximum size scenario. One of the challenges was that support from neighboring prefectures, which, like Osaka Prefecture, would be affected by the disaster, could not be expected, and it was unclear whether support could be expected in areas where subsequent earthquakes would occur. In addition, it was found that the lack of efforts to resolve the issue of whether it is possible to prepare not only for one scenario but also for multiple and diverse scenarios simultaneously, considering uncertainty, is an issue for the future. It was reaffirmed that, in reality, there are limitations in terms of cost, manpower, etc., and that organizational managers are required to make realistic decisions on what to select by setting priorities within that context.