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This is ALL THINGS CONSIDERED from NPR News. I'm Melissa Block. The tsunami that struck the Solomon Islands in the western Pacific yesterday has reportedly taken more than a dozen lives. There are local accounts of many more people missing.
Witnesses described waves at least 10 feet high sweeping over parts of the islands, washing away houses and people. The tsunami was caused by an earthquake that struck not far from the islands. Scientists say their instruments picked up the first signs of the quake thanks to a widespread warning system in the Pacific, but as NPR's Christopher Joyce reports, the news didn't get to the islands before the waves hit.
CHRISTOPHER JOYCE: Ever since the huge tsunami of December, 2004 in the Indian Ocean, the one that killed some 230,000 people, scientists have been trying to improve their ability to predict tsunamis. The Pacific Tsunami Warning Center in Hawaii monitors a worldwide network of seismic stations where detectors pick up vibrations in the earth's crusts.
Two scientists were on call there when the quake hit yesterday. Center geophysicist Barry Hirshorn says at first they didn't have enough information to get a fix on exactly where the quake was.
Mr. BARRY HIRSHORN (Geophysicist, Pacific Tsunami Warning Center): You need at least four or five stations to triangulate the earthquake properly, and at that point, we had two. So we just basically sat there waiting for seismometers, for that data to come in - which you know is kind of a serious problem because those minutes we're waiting are extremely valuable minutes.
JOYCE: Within about 15 minutes of the quake, the center sent out a warning saying it could create a tsunami. The warning goes electronically to scientists and public safety officials around the world, but the quake struck only about 30 miles from the Solomon Islands. Hirshorn says the tsunami probably rolled onto land within five minutes of the quake.
Mr. HIRSHORN: The only way to warn the local populations are to have local tsunami warning systems that have very dense networks and can respond quickly. We have one in Hawaii. In Hawaii, we can issue a warning in about three minutes.
JOYCE: But the Solomon Islands doesn't have that kind of sophisticated warning system. That would require dozens of costly tide gauges and tsunami detectors. The quake was a big one, magnitude 8.1. It was also a thrust-fault quake. Geophysicist Amy Vaughan of the U.S. Geological Survey's Earthquake Center says that kind of fault often produces a tsunami.
Ms. AMY VAUGHAN (Geophysicist, Earthquake Center, United States Geological Survey): It means that one plate moves over the other plate, and the ground moves up, basically, and uplifts the water above it, which is what creates the tsunami. As the water uplifts, it recedes at the shoreline, then the tsunamigenic waves roll along the ocean and roll, you know, toward the land masses.
JOYCE: Vaughan says another reason for the big tsunami was the shallow depth of the quake, only about seven miles below the sea floor.
Ms. VAUGHAN: If you have a quake that's very deep, it won't move the earth to the same extent, and it won't certainly uplift the earth, you know, in the way that creates the tsunami.
JOYCE: Scientists say they've seen some 20 good-sized aftershocks since the quake. Though the tsunami threat has subsided for the moment, they say the quake could have created stress in nearby faults, which could lead to more undersea earthquakes.
Christopher Joyce, NPR News.
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