How Fragile is the Solid Earth Beneath our Feet
By E. Kirsten Peters, Special to the Huntington Beach News
Geology has surely been in the news lately, with the price of petroleum moving relentlessly upward, a threat to global economic recovery because oil is so central to industrial society the world around. But now matters are suddenly worse.
Even geologists like myself, used to the ferociously destructive power of earthquakes, have been taken aback by the tragic news from Japan. The largest seismic event since earthquakes were first measured in that nation, near an 8.9 on the Richter scale, has clearly devastated sections of the northeast coast, and major aftershocks will rock the region for at least days to come.
The epicenter of the massive quake was under the sea, and a tsunami was immediately triggered by the event. The word “tsunami” has replaced what older readers may remember as a tidal wave, a name that was highly misleading because tsunami have nothing to do with the tides. The name tsunami is Japanese, a fact that shows Japan has been plagued by earthquakes and tsunami for as long as Japanese civilization has existed.
Tsunami are usually caused by movement of the solid sea floor, a lurch either up or down, that sends an enormous body of water on the move. The water packs a great deal of energy, like an enormous sledgehammer.
As a tsunami flows into more shallow conditions near the coast, the height of the wave increases more and more. That’s why ships far out to sea are not tossed by massive waves, but people in a harbor can see a truly enormous surge of water coming toward them. The water can spill far inland, as it clearly has done in northeast Japan.
Tsunami travel fast – at literally hundreds of miles an hour. Because of that fact, there was little time between the quake itself and the tsunami hitting the coast of Japan. Much of the evident destruction of the quake is from the effects of seawater inundating the land, sweeping whole buildings off their foundations, undermining roads and most unfortunately of all, quickly sweeping many local residents to their deaths.
Because tsunami travel across the entire Pacific Ocean, damaging coasts thousands of miles away from the original earthquake, scientists have a tsunami warning system in place 24-7. Nothing is perfect, but it’s a good system, and warnings in Hawaii preceded the arrival of the tsunami there. So far, Maui has had the highest wave, one recorded at about 7 feet.
As usual with massive earthquake damage, fires have broken out and are burning out of control in some cities. Fires often follow major seismic events because natural gas pipelines are cracked and start to leak, and because electric lines fall and create sparks. To make matters worse, fire fighters can be hampered in their work because water mains are broken.
We must all wish the Japanese people well as they start to cope with what has happened, and the U.S. has already pledged support for whatever the government of Japan thinks it needs to respond to the massive damage along its northeast coast.
But we Americans should also find some time to reflect on the fact that two regions of the Lower 48 stand at risk of similar events – and we are generally less prepared than the Japanese to deal with major quakes.
The first part of the country known to face earthquake dangers is, of course, the west coast. California most famously, but Oregon, Washington and inland states like Nevada are all slated for massive quakes in the future. But it’s also true that the central part of the country, in the region centered around where Missouri, Kentucky and Tennessee all come together, is another place where we geologists are sure there will be massive quakes.
We’ve got to learn from what we now see in news reports coming out of Japan. We can do better on everything from protecting our infrastructure to having family plans in place for emergencies.
Let’s let the tragic event in northeast Japan be a wake up call right here at home.
Huntington Beach News 18582 Beach Blvd. #236 Huntington Beach, CA 92648 Ph. (657) 845-7475 Email: email@example.com