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Catastrophes in perspective

by Donald Prothero, Mar 06 2013

Two years ago this coming Monday (March 11, 2011), the Sendai quake and tsunami struck Japan, and shocked the world. The media gave it saturation coverage for weeks, especially when it appeared that several nuclear reactors were damaged and might leak radiation. It also affected me personally, because my new book Catastrophes! had just been published by Johns Hopkins University Press, and the PR agents for my publisher soon had me talking about earthquakes and natural disasters to every kind of media, from two stints on MSNBC, to radio appearances on BBC, NPR, and many local outlets, to an editorial written for the Los Angeles Times in just 2 hours before deadline (which led to a call from Mayor Antonio Villaraigosa). Everyone wanted to hear about the danger of quakes, and I spent most of my time on the air debunking the common fears and misconceptions.

Such fears are particularly common when it comes to earthquakes. People who have never experienced one are deathly afraid of them, even though they are extremely unlikely to kill anyone in the United States thanks to our building codes and construction. (The same is not true of many underdeveloped countries in Asia, where the loss of life can be extreme). I’ve run into all sorts of people terrified of quakes that they have never actually felt, yet they don’t even flinch at deadlier events like hurricanes and tornadoes. There are all sorts of legends associated with quakes, from “earthquake weather” (an urban myth) to the idea that California will fall into the sea (no, it’s sliding north to Alaska at a few cm per year on average) to the myth that fault lines look like huge deep chasms floored with lava as in the first Christopher Reeve Superman movie (no, they just form straight valleys on the ground: chasms are due to landsliding far from the fault). I’ve lived through every Southern California quake since I was born, including the 1971 Sylmar quake, the 1987 Whittier quake, and the 1994 Northridge quake. When I was in New York in August 2011, I even got to experience a rare eastern quake (the Virginia quake that shook the 10th floor of the Frick Wing of the American Museum while I was visiting), then ironically, I had to leave later that week and cancel my talk to NYC Skeptics on “Catastrophes!” because Hurricane Irene was on the way.

Quakes are particularly scary to people, probably for two reasons: they are unpredictable (unlike weather events, which give some warning); and they shake our confidence in terra firma, which we have all grown up to assume cannot move. Psychologists have shown that human beings are notoriously poor at judging relative risks, and assessing which threats are really serious and which ones are exaggerated. For deeply held psychological reasons, people are far more afraid of dying from a snake bite or in an earthquake, even though these are staggeringly improbable events for most people in the United States. Only 5 to 10 people die of snakebite each year, and earthquakes have killed an average of only 6 people per year in the past century. Yet because of these irrational psychological reasons, we are unjustifiably afraid of them. Because snakes trigger a primordial fear response in our brain, we are terrified of them. When we were small vulnerable hominids running across the African savanna, snakes were a real threat to us, because many African snakes, like mambas and cobras, are poisonous. But now that snakes are so heavily slaughtered in this country (despite the fact that most American snakes are non-poisonous), we are much more a threat to them than they are to us.

Pie chart showing relative risks of death due to different natural disasters. From Borden and Cutter (2008)

Pie chart showing relative risks of death due to different natural disasters. Quakes are listed as “Geophysical.” From Borden and Cutter (2008)

A more objective way of assessing real threats is to look at cold hard statistics, as an actuary or insurance adjuster does. An article by Borden and Cutter (2008) looked at deaths in the U.S. from all natural hazards from 1970 to 2004. Despite the fact there were several big California earthquakes (1971, 1987, 1994) and large hurricanes during that time window, you would never guess what the number one killer was. It was not even a topic that we think of as catastrophe, since it happens so often and so slowly. The top killers among natural hazards in this country are…. heat waves, storms, and winter!

Yes, earthquakes, hurricanes, and other extreme weather events are terrifying disasters, but the biggest killers are slow and subtle: heat waves and drought. Likewise, we take severe storms and the bitter cold of winter for granted since they happen so often, but they kill a lot more people than more dramatic events like tornadoes, hurricanes, and earthquakes. Notice that hurricanes, earthquakes, and landslides are near the bottom of the list with less than 2% of the total deaths. Even though hurricanes and tornadoes are potentially very dangerous, we usually have some warning of when they are coming, and most people take shelter or evacuate when warned. Volcanic events did not even make the list, since the small Mt. St. Helens eruption was the only deadly volcanic event in this country for better than a century.

Map showing the relative risk of death in various regions of the U.S., with blue being safest and red being most hazardous. Note that it does not correspond to the quake zones of California, but to the South and the Rockies, where the death from storms, hurricanes, and heat waves are more likely.

Map showing the relative risk of death in various regions of the U.S., with blue being safest and red being most hazardous. Note that it does not correspond to the quake zones of California, but to the South and the Rockies, where the death from storms, hurricanes, and heat waves are more likely. From Borden and Cutter (2008)

Borden and Cutter (2008) also plotted the risk on a map of the U.S., organized county by county. If you asked anyone where the most dangerous places to live in the U.S. are, they would probably point to California with its earthquakes and landslides and brush fires, and maybe the Gulf Coast with its deadly hurricanes. But as the map shows, the opposite is true. Coastal California was one of the least hazardous in this regard (because we seldom get extreme killer weather of either hot or cold variety). The most deadly regions turned out to be the Deep South, where severe heat and humidity is common, and where occasional hurricanes only add to the carnage. Also dangerous was “tornado alley” in the southern Plains, with heat, drought, and tornadoes, and the southern Rocky Mountain region, with its desert heat and flash floods. The northern Plains and Rockies and Midwest were also death “hot spots” due to extreme cold and drought and occasional flooding. The rest of the country did not show any striking trends one way or another. What you don’t see is any strong correlation of high death risk with the fault zones map or even with the Gulf Coast-Florida hurricane zone.

Let’s put that in an even broader perspective. Many people are terrified of earthquakes and tornadoes and hurricanes, but these evens are not something to lose sleep over except when there are clear warnings that a hurricane or tornado is coming. We should be more careful and worried about heat waves and severe winter storms, but we’re so accustomed to these each year that we don’t realize how deadly they are. But worrying about natural disasters looks absurd in the face of where the real risks come from: your cheeseburger and French fries, your car, cigarettes, and all sorts of things you encounter every day. Borden and Cutter (2008) point out that for the 20,000 people killed by natural disasters in the U.S. during the study period from 1970 to 2004, there were 652,000 deaths from heart disease alone (more than 30 times the natural disaster total)! There were 600,000 deaths from cancer (also 30 times the total from natural disasters). Of cancer deaths, almost a third were from lung and other cancers due to smoking. Colorectal cancer, pancreatic cancer, prostate cancer, and breast cancer were the other biggest killers. There were 143,000 deaths from stroke, 130,000 from chronic lower respiratory diseases (bronchitis, pneumonia), and even 117,000 killed in accidents (mostly car accidents). If we really took the issue of risk seriously and evaluated it objectively, we would do well to worry much more about our diet and exercise, get frequent health checkups, stop smoking, and modify our driving habits. We may fear death in an earthquake or hurricane, but lunch, cigarettes, and driving are much more deadly to you!

References

  • Borden, K.A., and Cutter, S.L. 2008. Spatial patterns of natural hazards mortality in the United States. International Journal of Health Geographics 2008, 7:64
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Rating: 4.7/5 (12 votes cast)
Catastrophes in perspective, 4.7 out of 5 based on 12 ratings

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20 Responses to “Catastrophes in perspective”

  1. Trimegistus says:

    Interesting post. One can see these results a bit more clearly in Europe: they don’t get much in the way of hurricanes or tornadoes, but every summer one hears of elderly people dying in heat waves.

    • Daniel says:

      Probably because air conditioning, especially in private residences, is less common in Europe than it is in the US, particularly in France. 90 to 100 F in France, I believe, is pretty infrequent. It gets much hotter more often in cities such as Chicago.

      • Donald Prothero says:

        As confirmed by the recent US heat waves, where most of the death occurred in poor neighborhoods without AC, with elderly people with limited mobility and no AC

      • LovleAnjel says:

        Also people who live in poorer neighborhoods are unlikely to open windows or doors at night. Their apartments become ovens. This was a major factor in the Chicago heat wave in the ’90s.

    • Beelzebud says:

      Yeah we also see deaths during heat waves in the states. It’s not just in Europe that this happens…

      • Daniel says:

        I don’t have the inclination to look it up, but my general recollection is that there are far more deaths from heat waves in Europe than there are in the US. Like I say though, the difference is more due to geography and culture than anything else, for fear this turns into a political debate.

  2. Kyle Hill says:

    Great post Don,

    I focus a lot of work in my grad program on risk perception and you’ve hit the nail on the head here. Realigning judgments about what is actually dangerous has to be a main thrust for science communication, especially with a topic like climate change (“frog in a pot” comes to mind).

    (But snakes are “venomous” not “poisonous”)

  3. oldebabe says:

    While native or long-time Californians probably commonly experience a lot of earthquakes (which are just taken for granted if one lives in this State and is prepared), and only a few are big enough to cause widespread death and damage, you’ve not forgotten, I hope, another California earthquake that can hardly have been called small: the Loma Prieta, 1989, which caused spectacular damages and deaths in the SF, Bay Area, and peninsular areas.

    Earthquakes, landslides, hurricanes, tornadoes? One can mostly protect against them with knowledge, preparation, and mitigation. Cancer, not so much.

    • Donald Prothero says:

      Of course not! I play my “Loma Prieta” NOVA episode every time I teach seismology. But there were only 60 deaths in that event, and all the other natural disasters produce more than that EACH YEAR. Averaged over decades, quakes are less deadly than snakebites or lightning strikes

  4. Max says:

    If earthquakes are less risky than driving, why is earthquake insurance in California so expensive?

    • Donald Prothero says:

      Because insurers calculate how MUCH they will have to pay out in a given event. They pay out a steady stream of money settling auto insurance claims, and can predict their likely expenses precisely based on your driving record, age, etc. They are really guessing when they estimate what it would cost to insure in an earthquake, so they are taking a bigger gamble and charge more. Frankly, my experience has shown that they put in so many restrictions and the deductible is so high (not to mention the possibility that a giant quake will put them out of business, anyway), that I would never waste a cent on EQ insurance.

  5. Max says:

    Never cross a river because it is on average 4 feet deep.

    • Donald Prothero says:

      I get your point: major quakes will seem much worse than weather events (although they still won’t kill as many), and averaging diminishes this. But in scientific or actuarial terms, averages are everything, and a single rare event is not worth overturning the probabilities over the long term.

  6. Luara says:

    People who have never experienced [an earthquake] are deathly afraid of them, even though they are extremely unlikely to kill anyone in the United States thanks to our building codes and construction.
    What must be meant here is that a person in the U.S. is very unlikely to die from an earthquake.
    Not that earthquakes in the U.S. are unlikely to kill anyone. People die even in relatively minor quakes like the 1994 Northridge quake, which killed 57 people according to Wikipedia.
    The “Big One”, the magnitude 8 or so earthquake that will happen on the San Andreas Fault, will probably kill thousands of people.
    If you’re there when it happens, it won’t be much consolation that it won’t kill a large percentage of the U.S. population.
    And there are other kinds of suffering besides death, like being burned in the fires after the quake, or being hungry or thirsty.
    I would really rather not be there when it happens. Los Angelenos and LA buildings are very unprepared for it.

    • Donald Prothero says:

      Actually, thanks to the 1933 Long Beach quake and the Field Act, our building codes are better prepared for quakes than anywhere else in the country (as evidenced by the relatively small amounts of damage in the recent quakes). They’re not as stringent as those in Japan, and we should make them better, but most of the construction here held up well in previous quakes, and there are no more unreinforced masonry buildings out here that are such death traps in developing nations with frequent quakes.
      And yes, it won’t be fun to be here when the BIg ONe does strike. I’ve lived here when the quakes shut of power, water and gas for hours, and it wasn’t fun. But what you are saying is your emotional reaction to the terror of quakes relative to deadlier disasters like blizzards and heat waves. My point is that in scientific and actuarial terms, we have much more to fear from those annual events than we ever will from quakes.

  7. d brown says:

    Water is over one tank of gas from LA, if there are roads. A quake that is likely to kill many is along the Mississippi river in the Midwest. Its likely to be bigger that the West Cost big one.

  8. d brown says:

    Well meaning people buy fans for old people. In a house with nailed shut windows and even doors for safety, they act like convection ovens and kill move that no fans.

  9. Lines says:

    As a card carrying midwesterner I can honestly say that the first earthquake I was in (Hector Mine 1999, 29 PALMS 7.1 magnitude) was needing to change my shorts scary. Blizzard? No problem, get a coat. Tornado? Eh, go into the basement and watch the Wizard of Oz. THE GROUND IS NOT SUPPOSED TO MOVE. That is just unnatural. Ever hear the term “solid as a rock?” The unknown and in your face is a lot scarier than a probable, and slow known. A lion in the grass is a lot scarier than a psychedelic mushroom.

    • Donald Prothero says:

      Indeed! EXACTLY my point–that’s your emotional reaction, and that’s natural. It’s just not supported by cold hard scientific facts about the likelihood it will kill you, because we’re hard-wired to overreact to the rare event that affects us in deep psychological ways, and are not sufficiently wary of events that happen every year.

  10. Pete says:

    I’ve lived through all those quakes too. Some were more exciting than others. I thought the rolling waves from the Landers quake were amongst the most interesting – but I happened to be in Lancaster at the time :-)

    That being said … two things:

    1. If we consider that a large quake on the San Andreas is more probably in the next 30 years (since it is already overdue), then it also seems reasonable to expect larger shocks from the adjacent faults. Therfore, it doesn’t seem at all unreasonable to expect jolts of 5-6 magnitude from faults such as the Newport-Inglewood and the system that runs through Palmdale. These quakes have the potential to generate a LOT of damage, a good deal of fear from the community, some deaths, and huge financial losses. All this is coming.

    2. I’m not sure that the current estimate for the San Andreas quake (now estimated to be 8.1 magnitude if news articles are correct) may not be a little low. If that quake actually comes in around 8.5 to 9 then Los Angeles is not going to be a pretty sight to be seen. What worries me the most is not necessarily the destruction from the quake (although towns like Palm Springs and Banning will be a mess), but rather the generally poor preparations by most people. Most folks still have not done nearly enough to put away 3-4 weeks of food and water. It’s the civil unrest following the quake that probably poses the greatest danger.

    Just my thoughts.

    Pete, Redondo Beach