EXPLAINER: How long can trapped victims survive after an earthquake?

With the Philippines located along the Pacific Ring of Fire, earthquakes can occur at any moment. "The Big One," a potential 7.2 magnitude earthquake along the West Valley Fault is predicted to devastate Metro Manila and nearby areas.

Office of Civil Defense administrator Usec. Ariel Nepomuceno said on April 9 that the earthquake could leave tens of thousands dead and more than a hundred thousand injured.

Filipinos are urged to prepare for the disaster, but when an earthquake hits, among the most pressing concerns in the aftermath is the survival of those trapped under debris. 

When a 7.7 magnitude earthquake rocked Myanmar on March 28, victims were buried alive, including Tin Maung Htwe, a primary school headmaster, who survived five days entombed under his hotel bed.

"My body was burning hot, and all I needed was water. I couldn't get that water from anywhere, so I had to refill the water my body needed with fluids coming out of my body," he told AFP.

Rescuers also pulled a woman alive from the wreckage of a collapsed apartment building in Malanday on March 29, 30 hours after the quake hit.

In times like these, how long can an individual survive when trapped under debris or rubble after an earthquake?

Survivability factors

In an interview with PhilSTAR L!fe, Dr. Ted Esguerra, a Philippine Inter-Agency Humanitarian Contingent-Rescue Doctor from the Metropolitan Manila Development Authority and Energy Development Corporation Rescue, underscored that the survivability of any victims under rubble depends on certain factors.

For instance, young and aged victims are more vulnerable due to their mobility, judgment, and psychological configuration. The healthier or more fit the victim is, the higher the survival rate, Esguerra said.

The hotter or colder the weather is during the earthquake, the more dangerous, he added.

"If it's too hot, you might dehydrate so fast and be prone to heat illness, which will lead to heat stroke and end-organ damage to death. If it's too cold, you will get hypothermia and be prone to Tomcardica arrhythmia to death."

A Tomcardica arrhythmia, or tachycardia, refers to having a fast heart rate over 100 beats a minute.

Trapped victims without access to water for three days and those who are injured have a narrower chance of survival, the doctor added.

This was echoed by Dr. Karlo Dizon Baybayan, an Emergency Medicine Resident Physician.

He said that if a person is trapped in a place without resources due to an earthquake, survival without water is usually about three to five days, as dehydration "sets in quickly and can cause serious problems, especially in hot conditions or if the person has injuries."

Baybayan added, "Without food, though, the body can hold out much longer—usually up to 30 to 60 days. However, once the body starts breaking down vital organs, survival becomes harder." 

The physician also explained that when the body starts shutting down from dehydration, it generally "struggles to maintain fluid balance, leading to a rapid heart rate, low blood pressure, dry mouth, decreased urine output, and even confusion."

Lack of oxygen and exposure to dust are also huge risks in disasters like earthquakes, especially when trapped, as per Baybayan.

"Without enough oxygen, the body can’t function properly, especially the brain and heart, leading to serious damage. The body tries to compensate by speeding up the heart and breathing, but if oxygen levels stay low for too long, it can cause organ failure. Dust, especially tiny particles, makes things worse by irritating the lungs, causing difficulty breathing and increasing the risk of severe lung conditions, which makes it even harder to get oxygen into the body," he explained. 

Nonetheless, Baybayan noted that survival without food or water, oxygen, and exposure to dust may depend on a person’s age, health conditions, and body size or type.

Esguerra, meanwhile, emphasized that it is important to determine a victim's position if trapped, like if they are pinned down, supine, or prone, and what body part is trapped, among other things. 

Voids and vents where air can pass through can give victims a higher percentage of survival, he said. But if an individual is trapped under rubble and covered with damp soil, their chance of survival is slimmer.

"Do you see any spruce of light from the outside? Do you smell any gas or whatever odor? Is there much headroom for you to roll or crawl? Do you have emergency items with you, like a light or whistle? Can you see your location and if it's debris-free, void, or pocket? Can you see or feel your injury? Are there sturdy tables or furniture that home your void?" he said. 

Citing Brow University geophysicist Victor Tsai, Esguerra said that pockets refer to survivable void spaces or debris-free spaces where trapped victims might survive. 

Search efforts

When rescuers are faced with multiple collapsed structures, Esguerra said that they follow the International Search and Rescue Advisory Group or the INSARAG triaging system to prioritize their search efforts. 

In this system, the sites are categorized into four groups: A, B, C, and D. This system ensures that rescuers focus their efforts on the areas with the highest chance of saving lives first.

Category A refers to areas with confirmed live victims within 12 hours of the incident, meaning immediate attention is required. 

Meanwhile, Category B covers sites where live victims are confirmed, but more than 12 hours have passed, indicating a slightly lower priority but still urgent. 

Category C, on the other hand, includes locations where there is a possibility of live victims, but it hasn't been confirmed whether anyone is alive or even present in the debris. 

Finally, Category D represents areas with no confirmed live victims, where only deceased individuals are present.