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        April 15, 2008

(CNN Student News) -- April 15, 2008 Swarm of Quakes - Consider the significance of a swarm of earthquakes in the Pacific Northwest. MONICA LLOYD, CNN STUDENT NEWS ANCHOR: It's Tuesday, and you've found your way to the start of a new edition of CNN Student News. Thanks so much for joining us. I'm Monica Lloyd. First Up: Swarm of Quakes LLOYD: First up, scientists are warning residents in California to get ready for the big one. According to new calculations, there's a 99.7 percent chance that an earthquake of magnitude 6.7 or larger will strike the state in the next 30 years. The last time a quake that big hit California, it caused $25 billion in damages. California sits on part of the North American plate, and as Keeley Chalmers of affiliate KGW tells us, there's been a lot of seismic activity on it recently in the Pacific Northwest. (BEGIN VIDEO CLIP) KEELY CHALMERS, NEWSCHANNEL 8 ENVIRONMENTAL REPORTER: The swarm of quakes started a couple of weeks ago off the southern Oregon coast. The latest, a magnitude 5, struck about 200 miles west of Bandon. VICKI MCCONNELL, OREGON STATE GEOLOGIST: It's interesting, but it's not something that we consider threatening. CHALMERS: State geologist Dr. Vicki McConnell has been monitoring the quakes. She says they've all been happening along the same fault line, but she adds they are not related to the nearby Cascadia Subduction Zone. MCCONNELL: These are relatively shallow. They are only occurring about six miles deep. CHALMERS: Scientists believe the Cascadia Subduction Zone caused a magnitude 9 earthquake here in the Pacific Northwest 300 years ago. McConnell says the recent quakes are much more shallow, measuring magnitude 5 or smaller. MCCONNELL: They don't have enough of a magnitude, and they're not the type of movement that we would worry about tsunamis or anything else. SCOTT BURNS, PORTLAND STATE UNIVERSITY GEOLOGY PROFESSOR: We have been following them. CHALMERS: Portland State University geology professor Scott Burns is also monitoring the quakes. He believes these tiny tremors are a good thing. BURNS: If you have a whole bunch of small earthquakes, that's good. You're releasing all that energy; that's good. CHALMERS: And although they are not directly tied to the Cascadia Subduction Zone, Burns wonders whether these quakes could be a precursor to a much bigger one to come. BURNS: The question, are we going to get the big one? The answer is yes. The question is when, and we don't know. CHALMERS: And that could be hundreds of years away. These quakes now, simply tiny reminders of our constantly changing Earth. (END VIDEO CLIP) Spoken Word JACQUI JERAS, CNN METEOROLOGIST: When we see a swarm like this, these are individual earthquakes that kind of happen in the same general area. But when you have a large quake and then several aftershocks, the aftershocks tend to be a little bit weaker. Just to kind of give you an idea of where this is, I put it on Google Earth, and we put on data from the last couple of days to show you where quakes have been. There you can see the Pacific Northwest, and all of these dots that you can see over here off the coast, those are some of the more recent quakes that we've had. This blue line here, that's what we call the "subduction zone." So, that's where the plates, one lays on top of the other, so we would tend to see more activity here. But most of the swarms have been farther out over the Juan de Fuca plate. Something to watch, and I guarantee you those scientists, if anything big comes after this, they are going to try and find some kind of relation. Promo LLOYD: California is one of the most active areas in the world for earthquakes. What are some others? Our Learning Activity can help you track them down. It lets students research where major quakes have taken place and examine why some regions are more prone than others to these natural disasters. Check it out at CNNStudentNews.com!

    

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