Public Health and Earthquakes

jill's picture

More than a million earthquakes worldwide occur each year. That’s about two earthquakes a minute. More than 900 of those are potentially damaging (magnitude 5 or greater) earthquakes. With OpenHazards.com tools, you can learn more about where those damaging earthquakes are likely to strike, and make decisions about whether and how to prepare.

When we think about preparation, we usually assume we’re talking about some form of home retrofit: bracing cripple walls, bolting foundations, strapping water heaters, anchoring bookcases to walls, installing gas shut-off valves, etc. The health of our homes, schools, and places of business is one aspect of concern, but an even more devastating potential consequence of earthquakes we need to consider has to do with our own health and personal safety. Each year, urbanization is accelerating in seismically active parts of the world whose population densities reach 20,000 to 60,000 inhabitants per square kilometer.

The largest earthquakes aren’t necessarily the deadliest. Since the turn of the new century, the world’s ten deadliest earthquakes were actually equal to or smaller than the ten largest earthquakes. More than 455,000 people have died in earthquakes since 2000, most in densely populated areas of China, Pakistan, Sumatra, Iran, Indonesia, Afghanistan, and India. Although earthquake-related deaths are fewer in the United States (about 3,600 in the last century), increasing population growth in areas of high seismic risk has greatly increased the number of people at risk.  Researchers estimate that a repetition of the 1906 San Francisco earthquake, which measured 8.3 on the Richter scale, could cause 2,000 to 6,000 deaths and 6,000 to 20,000 serious injuries. A repeat event of the New Madrid, Missouri seismic zone could produce a magnitude 7.6 earthquake, which would be damaging over 200,000 square miles. And the eastern United States is not immune: for example, Charleston, South Carolina, experienced a magnitude 6.8 (Intensity X) earthquake in 1886 that killed 83 people and was felt over most of the United States east of the Mississippi River.

While we don’t like to think about injuries or deaths due to earthquake hazards, both are real and present dangers. In most earthquakes, people die from being crushed by falling buildings and other structures. According to Dr. Eric Noji, an international expert on health issues related to disasters, deaths resulting from major earthquakes can be instantaneous, rapid, or delayed. Instantaneous death can be due to severe crushing injuries to the head or chest, external or internal hemorrhage, or drowning from earthquake-induced tidal waves (tsunamis). Rapid death occurs within minutes or hours and can be due to asphyxia from dust inhalation or chest compression, hypovolemic shock, or environmental exposure (e.g., hypothermia).  Delayed death occurs within days and can be due to dehydration, hypothermia, hyperthermia, crush syndrome, wound infections, or postoperative sepsis.

Noji says the majority of people requiring medical assistance following earthquakes have minor lacerations and contusions caused by falling elements like pieces of masonry, roof tiles, and timber beams, while the next most frequent reason for seeking medical attention is simple fractures not requiring an operation. “Light” injuries usually require only outpatient-level treatment and tend to be much more common than severe injuries requiring hospitalization. Research indicates that many more injuries are treated at home, making it difficult to estimate the true extent of injuries from earthquakes.

While trauma caused by the collapse of buildings is the cause of most deaths and injuries in most earthquake, a surprisingly large number of people need a doctor’s attention for serious conditions related to an earthquake event, including acute myocardial infarction, exacerbation of chronic diseases such as diabetes or hypertension, anxiety and other mental health problems such as depression, respiratory disease caused by exposure to dust and asbestos fibers from rubble, and near drowning caused by flooding from broken dams. Huge amounts of dust are generated when a building is damaged or collapses, and dust clogging the air passages and filling the lungs is a major cause of death, both immediate or delayed, for many building-collapse victims. Noji also notes that there is a growing body of evidence that nonstructural elements (facade cladding, partition walls, roof parapets, external architectural ornaments) and building contents (glass, furniture, fixtures, appliances, chemical substances) can cause a substantial number of deaths following an earthquake.

I’d like to invite our site visitors to comment or offer your own ideas on how to avoid injury or death from an earthquake. I’ll continue this theme in future blogs.

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