WEBVTT - Will a really big earthquake sink Western California?

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<v Speaker 1>Welcome to Brainstuff from house stuff Works dot com where

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<v Speaker 1>smart happens. Hi. I'm Marshall Brain with today's question, and

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<v Speaker 1>i also have a funny little story that I'm going

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<v Speaker 1>to stick at the end of this podcast and ask

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<v Speaker 1>you a question about it. So here's the question. Is

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<v Speaker 1>it true that scientists are predicting a really big earthquake

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<v Speaker 1>that will sink western California. This often comes up when

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<v Speaker 1>people talk about earthquake activity along the Pacific coast of

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<v Speaker 1>the United States. Seismologists have predicted that a massive scale

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<v Speaker 1>eight point oh or higher on the Richter scale earthquake

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<v Speaker 1>will shake that region sometime within the next thirty years

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<v Speaker 1>or so. This is the so called Big One that

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<v Speaker 1>makes many California residents understandably nervous and inspires a variety

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<v Speaker 1>of apocalyptic disaster speculations. But while the Big One would

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<v Speaker 1>definitely reek mass destruction, it would not sink part of

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<v Speaker 1>California into the ocean, nor would it break the state

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<v Speaker 1>off from the rest of the country or anything like that.

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<v Speaker 1>The idea comes from a misunderstanding of the seismic forces

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<v Speaker 1>that cause earthquakes in the region. To begin with, powerful

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<v Speaker 1>earthquakes occur frequently along the West coast of the United

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<v Speaker 1>States because the region is near a boundary between two

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<v Speaker 1>tectonic plates. If you've read How Earthquakes Work on How

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<v Speaker 1>Stuff Works, then you know that the Earth's surface is

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<v Speaker 1>made up of large, rigid plates that slowly drift over

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<v Speaker 1>the mantle layer below them. At the boundaries between these plates,

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<v Speaker 1>a number of things can happen. The Pacific Plate and

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<v Speaker 1>the North American plates simply grind against each other, one

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<v Speaker 1>creep slowly northwest and one creeps southeast. This boundary forms

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<v Speaker 1>a fault line that extends under the ocean and on

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<v Speaker 1>land along the West coast of the United States. The

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<v Speaker 1>San Andreas Fault in California is the piece that's on land.

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<v Speaker 1>Smaller faults form in the crush material near the boundary

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<v Speaker 1>line due to the forces of the plates pushing on

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<v Speaker 1>each other. Friction builds up along the fault because the

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<v Speaker 1>two sides are pushed very tightly together. If the force

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<v Speaker 1>of friction exceeds the forces moving the earth, then the

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<v Speaker 1>two sides will become locked, so they stop creeping. When

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<v Speaker 1>this happens, tension builds up along the fault line until

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<v Speaker 1>the force of movement is great enough to overcome that

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<v Speaker 1>force of friction and to break the lock. Then the

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<v Speaker 1>pieces of Earth suddenly snap into place, releasing a huge

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<v Speaker 1>amount of energy that causes big earthquakes in the Earth's crust.

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<v Speaker 1>Many scientists estimate that there is enough tension built up

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<v Speaker 1>along some locked California faults that when they do finally slip,

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<v Speaker 1>the earthquake will be extremely powerful. The Hayward fault particularly

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<v Speaker 1>concerns these scientists because it runs are heavily populated areas

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<v Speaker 1>in and around Los Angeles. The notion that part of

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<v Speaker 1>California will break off, though, was likely inspired by the

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<v Speaker 1>San Andreas fault. After all, since the fault goes right

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<v Speaker 1>through California, one part of the state is on the

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<v Speaker 1>Pacific Plate and one is on the North American Plate.

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<v Speaker 1>If those plates are moving in different directions, it makes

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<v Speaker 1>sense that the two pieces of California will move in

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<v Speaker 1>different directions too, and this is indeed the case. But

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<v Speaker 1>even in a massive shift along the fault, the plates

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<v Speaker 1>travel an incredibly short distance. It's a matter of ten

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<v Speaker 1>or twenty feet at most, and even the most extreme shifts,

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<v Speaker 1>the tension can't build up to the point that one

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<v Speaker 1>entire massive land will shift many miles in relation to

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<v Speaker 1>another one, so you will not see any sizeable piece

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<v Speaker 1>of land breaking away from any other. Instead, the pieces

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<v Speaker 1>of land will move away from each other slowly, very

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<v Speaker 1>very slowly, taking millions of years to make large scale changes.

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<v Speaker 1>One end of California may slowly drift so that it

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<v Speaker 1>eventually is underwater after millions of years, but this can

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<v Speaker 1>hardly be construed as sinking into the ocean. Pieces of

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<v Speaker 1>land don't just fall into the ocean, because that's not

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<v Speaker 1>how tectonic plates work. So let me shift gears here

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<v Speaker 1>and tell you a funny story. As many of you know,

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<v Speaker 1>I have been on a diet for about fourteen weeks

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<v Speaker 1>now and I've lost thirty seven pounds. So I got

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<v Speaker 1>this comment on one of my dieting blog posts from

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<v Speaker 1>a reader named Christine, and here's what she says. You're

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<v Speaker 1>doing a phenomenal job. I hope that you will continue

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<v Speaker 1>with updating us each week because reading your posts keep

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<v Speaker 1>my momentum going. Also, I listened to your podcasts and

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<v Speaker 1>I wanted to mention that you sound thinner. Sound is

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<v Speaker 1>in all caps. You don't sound throaty, almost as if

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<v Speaker 1>you've lost weight around your neck, so that is odd.

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<v Speaker 1>If you've ever read my blog posts about this diet

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<v Speaker 1>I've been on, it's called the Ducan Diet, and it's

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<v Speaker 1>worked pretty well to lose thirty seven pounds in roughly

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<v Speaker 1>three months. But I never would have expected or predicted

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<v Speaker 1>or calculated that it would have any effect on my voice.

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<v Speaker 1>So here's a question I'd like to ask. Do you

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<v Speaker 1>think my voice sounds different than say, three months ago.

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<v Speaker 1>If you listen to the podcast regularly, you know you've

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<v Speaker 1>probably heard my voice over a couple of months period.

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<v Speaker 1>Does it sound any different to you? And if it does,

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<v Speaker 1>would you mind leaving a comment? There's Facebook dot com

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<v Speaker 1>slash brain stuff. You could go there and just drop

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<v Speaker 1>a comment on the page. I just be curious to

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<v Speaker 1>know if this is something that is audible to people,

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<v Speaker 1>or if not, or if you don't use Facebook, then

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<v Speaker 1>email me at m brain at how stuff works dot com.

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<v Speaker 1>So it's Facebook dot com, slash brain stuff or m

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<v Speaker 1>brain at how stuff works dot com. I just be

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<v Speaker 1>curious if you can hear any difference. Thanks for more

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<v Speaker 1>on this and thousands of other topics, visit how stuff

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<v Speaker 1>works dot com and don't forget to check out the

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<v Speaker 1>brain Stuff blog on the how stuff Works dot Com

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<v Speaker 1>home page. You can also follow brain Stuff on Facebook

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<v Speaker 1>or Twitter at brain Stuff H. S W.