According to a new study published Thursday in the Lancet earthquakes can be devastating during and after they have come and gone.
Dr. Susan A. Bartels of the Beth Israel Deaconess Medical Center and Dr. Michael VanRooyen of Brigham and Women's Hospital, both in Boston, reviewed the medical literature on the health effects of earthquakes - and described them as “devastating.” They write that over the last decade earthquakes have caused more than 780,000 deaths -- almost 60% of disaster-related morality. More than a million earthquakes occur around the world each year, the equivalent of about 2 temblors per minute. Some of the world's largest and most populated metropolitan areas - Tokyo, Mexico City, India's Mumbai, Shanghai, Los Angeles, even New York City - are in seismic zones.
“Because earthquakes frequently affect populous urban areas with poor structural standards, they often result in high death rates and mass casualties with many traumatic injuries,” write authors. “These injuries are highly mechanical and often multisystem, requiring intensive curative medical and surgical care at a time when the local and regional medical response capacities have been at least partly disrupted,” write Dr. Bartels and Dr. Van Rooyen, who are also affiliated with the Harvard Humanitarian Initiative in Boston. “Many patients surviving blunt and penetrating trauma and crush injuries have subsequent complications that lead to additional morbidity and mortality.”
Unlike floods and hurricanes, which can cause a lot of deaths (mainly from drowning) but typically aren't associated with injuries that require ongoing medical or surgical care, earthquakes also inflict assorted traumas say researchers. They also damage roads, hospitals and other infrastructure, derailing emergency services and creating “a large, unmet need for complex surgical and medical care,” the co-authors wrote.
Authors cite crush injuries, in which pressure on muscles damages tissues and can lead to electrolyte imbalances, kidney failure, sepsis and death, broken bones, gangrene as some of the major injuries. There is also a surge of heart ailments after the earthquake. In the week of the 1994 Northridge earthquake, heart attacks rose 35% over the previous week (though in the 1989 Loma Prieta quake, there was no detectable rise in acute coronary events.) Victims have chest injuries, head injuries and spinal injuries. Infectious diseases proliferate when water and sanitation services are interrupted. Mental health problems such as depression and post-traumatic stress disorder have been reported; earthquakes are also associated with the highest rate of suicide of any type of natural disaster. Children are often at higher risk of injury and death during earthquakes than adults, the authors added.
Casualty rates of earthquakes vary from 1% to 8% of those at risk and the ratio of death to injury was approximately 1:3. Death is immediate for many. A second peak in mortality occurs a few hours later, corresponding to deaths from critical injuries including liver or spleen lacerations, pelvic fractures, and subdural hematomas. A third mortality peak occurs days to weeks later due to sepsis, multiorgan failure, and disseminated intravascular coagulation.
As people are displaced from their damaged homes, overcrowding in shelters with poor sanitation also can trigger infectious disease outbreaks and sepsis, which increases mortality 2.5-fold. However, the reviewers note that the role of corpses in such outbreaks tends to be exaggerated, except in the transmission of cholera.
“Understanding of the medical effects of earthquakes, especially in large urban centers, necessitates awareness of the regional seismic risk, structural vulnerability, local response capacity, and resilience of the curative medical services,” Dr. Bartels and Dr. Van Rooyen write. “A multidisciplinary approach is needed to create a mechanism for prevention, search and rescue, and medical response.”
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