To a fault: the bottom line on earthquakes

Q: How common are earthquakes in the Midwest and was the severity of this tremor a first for this area?

A: Between 1776 and the present, 170 earthquakes have been charted in Ohio of magnitude 2.0 or greater. There have been at least 150 below magnitude 2.0, which averages out to approximately 1½ earthquakes a year. This latest was not a first, severity-wise: Several others measured inbetween 5.3 and 5.4; in 1980, for example, an earthquake in Sharpsburg, Ky., measured 5.2.

Q: Can anyone predict a “big one” ever hitting the Midwest?

A: We haven’t reached that level of sophistication yet. That would require predicting, simultaneously, location, timing and magnitude, Kilinc says, “and that’s virtually impossible.” He adds that seismologists in San Francisco, may, however, say the probability of a magnitude 6 earthquake within the next 30 years is 50 percent.

Q: What is Cincinnati’s proximity to the nearest fault line?

A: Cincinnati is not on or close to a fault line, Kilinc says. The nearest active one is the New Madrid Fault Line, about 350 miles west of Cincinnati. The last major (7.5 or higher) New Madrid-line earthquake was in December 1811 and January 1812. The fault line actually closest to Cincinnati, Kilinc adds, is just south of Lexington, Ky., but it’s not currently active.

Q: People have commented that their dog or cat woke them up during this Midwest-based earthquake. Others say they’ve heard all their lives that animal behavior – and even illnesses of people – can predict an earthquake. How far back in history does such thinking go and is there any validity in it?

A: The U.S. Geological Survey says that references to unusual animal behavior before a significant earthquake date to 373 BC in Greece. Kilinc says that for many years, Chinese scientists in particular watched what they called precursors, such as animal behavior and radon in water, in terms of earthquake prediction. None of the signs they were watching for, he adds, showed up in Tangshan, China, on July 28, 1976. That’s the day an estimated 247,000 people died in China’s deadliest earthquake of the 20th century. Its magnitude was 7.8.

Q: For those who have been through a major earthquake in California, this has to seem like barely a rumble. Yet, for many Midwesterners, an earthquake can literally rattle the nerves! How seriously should we take such an occurrence and is there any preparation one can make for an earthquake?

A: Residents of any area should always be prepared for earthquakes, tornados, hurricanes and so forth, making logical preparations that are similar no matter the disaster. For example, if there’s a strong earthquake or tornado and electricity is lost, many people’s first reaction is to strike a match so they can see — and can cause an explosion in a gas line. Also, people tend to want to rush out of an area affected by an earthquake. Kilinc, a former California resident who’s been through many temblors in the Bay Area, says that most people are killed “trying to get in or out,” so staying put is important. Little things matter, too, such as not putting dangerous chemicals on upper shelves in a laundry room.

Q: Finally: Another widely spread urban legend claims that California will someday fall into the ocean. While that’s not going to happen, how long could it take, as the Pacific Plate moves, before Los Angeles is close to San Francisco?

A: California, Kilinc says, “will never fall into the ocean” because of a boundary called a transform fault. San Francisco will shift south and Los Angeles, north — but it will take a “long, long time” for them to meet. The USGS says that tectonic forces “in this part of the world are driving the Pacific Plate in a north-northwesterly direction with respect to the North American plate at approximately 46 millimeters per year in the San Francisco Bay Area.”

Source: University of Cincinnati