What I Learned About Earthquakes on My Lunch Hour
Today I went to a lunchtime lecture at Schlow Library downtown, to hear Penn State geoscientist Eliza Richardson talk about earthquakes. No special reason, really, except that we just finished the November/December issue of the magazine, so suddenly I have a little more time for such things. Lectures like these are a good way for us to scout possible stories for the magazine. And, besides, I know pretty much nothing about earthquakes.
In an hour’s time, I learned a lot. Here’s a sampling:
—Scientists would love to be able to predict earthquakes: when they’ll strike, where they’ll strike, and how big they’ll be. Richardson calls it the “holy grail” in her field.
—”The biggest earthquakes aren’t always the worst,” Richardson says. She showed three lists—the 10 biggest earthquakes in history, the 10 deadliest, and the 10 costliest—and pointed out that only two earthquakes appear on all three lists. (Those were the 2004 quake and tsunami near Sumatra and the 2011 quake and tsunami off the Japanese coast.)
—The so-called “World Series Earthquake” of 1989 in San Francisco was not quite as strong as the devastating 2010 earthquake in Haiti—the San Francisco quake was a magnitude 7.0, vs. 7.2 in Haiti—yet only 68 people died in San Francisco, vs. 159,000 in Haiti. “That’s all about infrastructure,” Richardson says: San Francisco has many buildings that are seismically retrofitted, while Haiti, an impoverished country, does not.
—Earthquakes happen along fault lines where two tectonic plates bump into each other, and “stress overcomes friction” along that fault line. “If the plate boundaries could all be lubricated with the scientific equivalent of WD-40, earthquakes would never happen,” Richardson says.
—Earthquakes happen far more often than people realize. Her title slide included a USGS-generated world map very similar to this one…
…which shows all earthquakes of magnitude 2.5 or greater just in the past 30 days.
You can click on the map to see it bigger. Obviously the fault lines along the West Coast of the Americas are pretty impressive, along with poor Italy, which is practically obliterated by all the dots.
—Speaking of Italy: Scientists often are hesitant (“cagey,” Richardson called it) about saying they’re working on earthquake prediction. She cited the 2009 L’Aquila earthquake in Italy as one reason: The city had been experiencing tremors for months, so a special meeting of seismologists was convened, and many people interpreted the scientists’ comments at that meeting as suggesting there was nothing to fear. A week later, a magnitude-6.3 quake hit the city, and more than 300 people died. Five scientists ended up standing trial for manslaughter—and were convicted. A higher court eventually overturned the convictions, but the events surely had a chilling effect on seismologists worldwide.
(You can read an interesting account of the L’Aquila quake and subsequent criminal trial at Smithsonianmag.com.)
—While seismologists can’t yet predict earthquakes, there’s been a lot of progress in the field in the past 10 years. Scientists are starting to pay more attention to silent earthquakes called “slow slip earthquakes,” which can be measured by GPS devices. These slow slips may turn out to be harbingers of a larger, far more damaging quake.
—There’s a fairly prominent fault line in the U.S. midwest, called the New Madrid (pronounced MAD rid) Fault, which in 1811 and 1812 spawned the largest earthquakes in U.S. history. If they happened today, says Richardson, they would level Memphis and several other cities. They reportedly shook the White House, hundreds of miles away, and caused church bells to ring in Boston.
(You can read more about the New Madrid earthquakes here.)
OK, there’s lots more, but I’ve probably babbled enough. Suffice it to say I think Richardson’s research is really interesting and would make for a great story in the magazine sometime.
The lecture was sponsored by Schlow Library as part of its Research Unplugged series; the fall schedule continues through Nov. 10.
Tina Hay, editor