Feeling the Earth Move

My husband, Steve, is a strange man and he recently hooked me into one of his unusual past-times: earthquake tracking. He looks at the United States Geological Survey (USGS) every day to view the latest earthquakes that have occurred around the world. He is tectonic-plate obsessed.

I asked Steve why he is attracted to moving, subterranean rock. He replied: “The Earth is a living thing and its way of letting off steam is volcanoes. When it’s not comfortable with its weight, it shifts around and we get earthquakes. The planet is alive.” Wow. Very poetic. He then added, “I just have a fascination with watching the destructive power of Nature.” Okay. That sounds a little less New Age, but very guy-like.

As you probably know, the Earth has seven to eight major and many minor tectonic plates. Basically, everything on the surface of the Earth rests on those plates, but unfortunately for us, they move. When they do, the results are earthquakes, volcanic activity, mountain-building and oceanic trench formation.

On the USGS “Latest Earthquakes in the World” web page,* all tremors magnitude 2.5 and above are listed. Anything 4.5 or above is in scary boldface. The really BIG quakes, 6.0 or above, are in alarming red. What grand purpose is there in tracking earthquakes? For the average person, none really, unless you’re sitting on top of a fault line. It does, however, give Steve and me something to talk about at the end of the day. For instance, this morning at 9:56 a.m. Universal Time, Santiago Del Estero, Argentina, had a whopping 7.0 magnitude earthquake. We looked that up on Google News and found that no one was hurt. That may be because it occurred at a depth of nearly 584 kilometers, or because no one lives in the area where it occurred.

Interestingly, Argentina is part of a large area of plate movements, around which, is something called the Ring of Fire. About 90% of the world's earthquakes and 80% of the world's largest earthquakes occur along the Ring of Fire, which is actually shaped like a horseshoe. But Horseshoe of Fire doesn’t sound as good, thus the present name. This Ring of Fire extends from Peru up the West Coast of South America to the West Coast of North America, up around the southern coast of Alaska and across the Aleutian Islands, down the coast of Eastern Russia, down through Japan, across Indonesia, and back out to the Tonga Islands and down into New Zealand. Most of the world’s volcanoes sit on the Ring of Fire.

This is a map of the Ring of Fire, which actually looks more like a malformed horseshoe.
Map is courtesy of the USGS.

Here are some interesting earthquake facts from the USGS:

• The largest recorded earthquake in the United States was a magnitude 9.2 that struck Prince William Sound, Alaska, on March 27, 1964. The earthquake and ensuing tsunami took 128 lives (tsunami 113, earthquake 15). Alaska is the most earthquake-prone state and one of the most seismically active regions in the world. Its residents experience a magnitude 7 earthquake almost every year, and a magnitude 8 or greater earthquake on average every 14 years. These may temporarily obscure Sarah Palin’s view of Russia.

• The largest recorded earthquake in the world was a magnitude 9.5 in Chile on May 22, 1960. When it occurred, seismographs recorded seismic waves all around the world. The earthquake shook the entire Earth for many days. Most of the casualties were because of large tsunamis which caused damage along the coast of Chile and in many areas of the Pacific Ocean. Puerto Saavedra, Chile, was completely destroyed by waves which reached heights of 38 feet and carried remains of houses as much as 2 miles inland. Tsunamis caused 61 deaths and severe damage in Hawaii, mostly at Hilo, where the run-up height reached 35 feet. Waves as high as 18 feet struck northern Honshu, Japan, about 1 day after the quake, where they destroyed more than 1600 homes and left 185 people dead or missing. Another 32 people were dead or missing in the Philippines after the tsunami hit those islands. Damage also occurred on Easter Island, in the Samoa Islands and in California.

• The world’s deadliest recorded earthquake occurred in 1556 in central China. It struck a region where most people lived in caves carved from soft rock. These dwellings collapsed during the earthquake, killing an estimated 830,000 people. In 1976 another deadly earthquake struck in Tangshan, China, where more than 250,000 people were killed. The earliest recorded evidence of an earthquake has been traced back to 1831 BC in the Shandong province of China.

• Only four states in the U.S. did not have any earthquakes, from 1975 to 1995. They were Florida, Iowa, North Dakota and Wisconsin. Florida and North Dakota have the smallest number of earthquakes in the U.S. Instead, Florida has opted for hurricanes and North Dakota for flooding, blizzards and tornados.

• Earthquakes occur in the central U.S. Some very powerful earthquakes occurred along the New Madrid fault in the Mississippi Valley in between 1811 and 1812. Because of the crust’s structure in the central U.S., shaking from earthquakes is felt at a much greater distance from their epicenters than similar size quakes in the western U.S. The New Madrid earthquakes caused the ground to rise and fall, bending trees until their branches intertwined and opening deep cracks in the ground. Huge waves on the Mississippi River overwhelmed many boats and washed others high onto the shore. Only one life was lost in falling buildings at New Madrid, but chimneys were toppled and log cabins were thrown down as far as Cincinnati, Ohio; St. Louis, Missouri; and in many places in Kentucky, Missouri, and Tennessee. Had our news media existed at the time, people would have been predicting the end of the world, culminating in a made-for-television movie about it.

Apparently, Steve got his co-workers at the independent bookstore addicted to earthquake tracking as well. He has a tendency to spread his craziness wherever he goes. They check it every day and it is the subject of conversation. Perhaps the attraction is the reminder that Nature is very powerful and no matter what technologies we develop, a good earthquake will trump them every time. Earth is big; people are small. For all of us, that is a very humbling and implacable truth to remember.

*If you want to track earthquakes, go to: http://earthquake.usgs.gov/earthquakes/recenteqsww/Quakes/quakes_all.php