Multi-Criteria Seismic Vulnerability Assessment of Healthcare Facilities using Fuzzy C- Means Clustering in Cox's Bazar

In the coastal districts of South Asia, the ground beneath the earth is not always still. Tectonic plates press against one another, storing energy that can release suddenly as an earthquake. When this happens, the danger is not just the shaking itself, but what happens to the buildings and systems that people rely on when the ground stops moving. Hospitals are the most critical of these systems. If a hospital collapses or becomes unreachable, the people who need care the most cannot get it, turning a natural disaster into a human catastrophe. For decades, engineers and planners have tried to predict which buildings are most likely to fail. They look at how strong a structure is and how hard the ground might shake. But this approach often misses a crucial part of the picture: a hospital might be built to withstand a quake, but if it is too far away for people to reach, or if it is already overwhelmed by the number of people it serves, it is still vulnerable.

A team of researchers set out to understand this complex reality in Cox's Bazar, a district in southeastern Bangladesh. This area is not only seismically active, sitting near the boundary where massive tectonic plates meet, but it is also home to the world's largest refugee camp. The region contains 184 healthcare facilities, ranging from small community clinics to large government hospitals, serving a population of over two million residents and nearly one million refugees. The researchers wanted to know which of these facilities were most at risk, not just from the shaking of the earth, but from the combination of shaking, distance, and the sheer number of people waiting for help. They used a method that treats risk as a spectrum rather than a simple list of "safe" or "unsafe," allowing them to see how different factors blend together to create specific types of danger.

The study began by gathering information on every single healthcare facility in the district. The team mapped their locations and calculated how long it would take to reach them by road under normal conditions. They also estimated how many people lived within a five-kilometer radius of each facility, a measure of how many lives depend on that specific building. Crucially, they looked at the structural importance of each building, noting that large hospitals are more critical to the survival of the community than small clinics. Finally, they simulated three different earthquake scenarios: a moderate event, a strong event that might happen once every 475 years, and a massive, rare event that could occur once every 975 years. For each scenario, they calculated how hard the ground would shake at every facility's location.

Instead of simply ranking the hospitals from most to least dangerous, the researchers used a computer technique that groups similar facilities together based on all these factors at once. This method allowed them to identify four distinct patterns of vulnerability that appeared consistently, regardless of which earthquake scenario they simulated. The first group consisted of large hospitals located in the coastal urban core. These facilities faced a double threat: they were situated in areas where the ground shaking would be most intense, and they were the primary destinations for emergency care. If these buildings were damaged, the entire district's ability to respond to a disaster would collapse. The second group included government hospitals and larger clinics that served huge populations. While they were not in the most dangerous shaking zones, they were at risk of being overwhelmed by the sheer number of people needing care, a problem known as demand overload.

The third and fourth groups revealed a more subtle kind of danger. One group of facilities, mostly small clinics in the interior and on islands, faced a risk of isolation. These buildings were often far from main roads, meaning that even if the structure remained standing, the roads leading to them might be blocked or too slow to traverse after an earthquake. The final group, which turned out to be the most surprising, consisted of facilities serving the massive refugee camps in the southern part of the district. These clinics were located in areas with the lowest risk of ground shaking in the entire district. However, they served the highest number of people, and the distance to reach them was significant. In a traditional analysis that only looked at earthquake intensity, these facilities would have been considered the safest. But when the researchers added the number of people and the travel time into the equation, these facilities emerged as having the highest risk of a capacity mismatch. They were the most likely to fail because the demand for care far outstripped their ability to provide it, even if the building itself did not crack.

The researchers found that this pattern of vulnerability was remarkably stable. When they changed the size of the simulated earthquake from a moderate tremor to a massive, rare event, the way the facilities were grouped barely changed. Only two out of the 184 facilities switched groups between the smallest and largest earthquake scenarios. This consistency suggests that the risks are not just about how hard the ground shakes, but are deeply rooted in the geography and the population distribution of the district. The study highlighted a critical flaw in how disaster planning is often done: focusing only on the strength of the building or the intensity of the shaking. By ignoring the number of people a facility serves and how long it takes to get there, planners might be protecting the wrong buildings.

The findings offer a clear path forward for emergency planners in Cox's Bazar and similar regions. The large hospitals in the city center need to be reinforced to ensure they can survive the strongest shaking, as their failure would be catastrophic. The facilities in the refugee camps, despite being in a safer seismic zone, need urgent attention to their access and capacity, perhaps through better road networks or pre-positioned medical supplies, because they are the most likely to be overwhelmed. The isolated clinics on the islands and in the hills need different solutions, such as helicopter landing sites or maritime evacuation plans, because their greatest risk is not the shaking, but the inability to reach them. This study proves that to truly protect a healthcare system, one must look at the whole picture: the ground, the roads, the buildings, and the people. Only by understanding how these elements interact can communities prepare for the day the earth moves.