[Feature: Thinking About Disaster Prevention] Earthquake Preparedness at Keio University: Focusing on Physical Infrastructure Measures

"Disaster prevention" is a broad concept that encompasses not only preventing disasters and suppressing or mitigating damage, but also emergency response and recovery efforts after a disaster occurs, as well as subsequent reconstruction, crisis management, and BCP (Business Continuity Planning). Here, among Keio University's disaster prevention initiatives, we will focus on "earthquakes," which are the disasters most likely to cause the greatest damage, and explain physical infrastructure initiatives such as facilities and equipment at each stage of disaster prevention.

With current science and technology, it is impossible to prevent earthquakes from occurring, and the effectiveness of earthquake prediction is still not at a level where it can be relied upon.

Therefore, efforts to suppress and mitigate damage when a large earthquake occurs become the realistic countermeasure. In terms of physical infrastructure, this means ensuring that buildings can withstand large earthquakes. In Japan, buildings are constructed in accordance with the Building Standards Act. By complying with the Building Standards Act, buildings meet the established seismic standards and obtain the necessary seismic resistance.

However, seismic standards are frequently reviewed. While the seismic standards revised in 1981, the so-called "New Seismic Design Standards," were set so that buildings would not be damaged by earthquakes of upper 5 intensity on the Japanese seismic scale, the new standards ensure that buildings have the strength to withstand earthquakes of upper 6 to 7 intensity without collapsing or crumbling, even if they sustain some damage. Consequently, the degree of damage from a major earthquake differs significantly between buildings built before and after these new standards. In fact, during the 1995 Great Hanshin-Awaji Earthquake, buildings constructed under the New Seismic Design Standards suffered almost no major damage, whereas many buildings built under the old standards suffered devastating damage, including collapse.

In the years following the Great Hanshin-Awaji Earthquake, Keio University conducted seismic diagnostic tests on nearly 100 of its buildings that had been constructed under the old seismic standards. A seismic diagnosis examines whether a building's structure has seismic performance equivalent to buildings designed under the New Seismic Design Standards. It is evaluated using several indicators, the most straightforward of which is the Is value (Seismic Index of Structure: calculated for each floor of a building, considering its strength and ductility against seismic force). If this Is value is 0.6 or higher, the building is considered to have seismic performance equivalent to a building constructed under the New Seismic Design Standards (the Ministry of Education, Culture, Sports, Science and Technology sets the seismic performance standard for school buildings slightly higher, at 0.7, rather than the minimum Is value of 0.6).

Based on the results of the seismic diagnoses, Keio University prioritized buildings judged to need reinforcement—such as those with an Is value below 0.6—based on factors like seismic resistance and the age group of the facility users, and formulated a seismic reinforcement implementation plan. In accordance with this plan, seismic reinforcement work has been carried out sequentially since 2003. By 2013, reinforcement work had been completed on more than 30 buildings, and reinforcement is now almost complete for all buildings originally diagnosed as needing it.

As the next stage, we are currently proceeding with seismic diagnoses and reinforcement for small-scale buildings that were not initially diagnosed. Furthermore, for the Old University Library in Mita, which requires the preservation of its exterior design as an Important Cultural Property, standard seismic reinforcement methods cannot be used. Therefore, we are undertaking the difficult task of ensuring seismic performance through the seismic isolation retrofit method (a method of converting an existing building into a base-isolated structure), which is scheduled for completion in the spring of 2019. Through these efforts, as of the spring of 2018, the ratio of seismically reinforced buildings to the total buildings owned by Keio University has reached 98.4% by floor area.

Furthermore, earthquake damage is caused not only by the collapse or damage of building structures but also by the peeling or falling of non-structural components such as ceiling materials, exterior materials, and equipment. Promoting the seismic reinforcement of these non-structural components is a challenge for the future.

In the event of a major earthquake, an emergency response to the damage caused is necessary. Even in terms of physical infrastructure, it is important to make accurate judgments regarding the safety of buildings after a disaster. We must prevent secondary disasters by conducting "emergency risk assessments" to determine if buildings damaged by the earthquake are safe and can withstand aftershocks, and by prohibiting entry to buildings where safety cannot be guaranteed. Architectural engineers from the facilities department who hold qualifications as emergency risk assessors respond to this by inspecting each building, confirming the damage status, and verifying safety.

Additionally, an organization must restore functions degraded by a disaster as quickly as possible. While this relates to crisis management and BCP, the challenge for physical infrastructure is how to support this from a facilities perspective. As mentioned earlier, the current Building Standards Act requires a minimum level of seismic resistance that prevents collapse during a major earthquake. However, considering economic factors—such as how much seismic resistance should be required for a major earthquake that might occur only once in a building's lifespan—the approach taken is that for extremely rare large-scale earthquakes of upper 6 to 7 intensity, some degree of damage is unavoidable, provided the building does not collapse. If reconstruction or major repairs are required due to damage, that building cannot be used immediately.

However, for buildings that serve as bases during a disaster, it is not enough that they simply do not collapse; they must be able to function immediately after a major earthquake. Such buildings are required to have the seismic performance and equipment to make this possible. We must also assume that external supplies of electricity, gas, and water will be cut off. Generally, the amount of food and drinking water stockpiled and the specifications of equipment for disasters are intended to cover three days after a disaster occurs. However, in reality, there are many factors that need to be considered, such as the assumed number of people for calculating stockpile amounts and the scope of power backup during outages. We recognize how to technically achieve this as a challenge for the future.

So far, I have described initiatives regarding the physical infrastructure side of earthquake countermeasures, but disaster prevention is more effective when both the physical (hard) and operational (soft) aspects work together seamlessly. Improving organizations, systems, and frameworks for disaster prevention, as well as raising the awareness of faculty, staff, and students regarding disaster and crisis response, is extremely important for preventing disasters and for suppressing and mitigating damage when they occur. We believe it is important that the development of physical infrastructure, which our Office of Facilities and Property Management is primarily responsible for, is not done in isolation, but is carried out with an awareness of and in coordination with the development of operational systems.

*Affiliations and titles are those at the time of publication.