Earthquakes: Top 10 Questions

April 2011

Thanks to Geoscience professors David Rodgers of Idaho State University and Kasper van Wijk of Boise State University for the answers.

1: Would we have a better chance of surviving an earthquake if our houses were made of concrete?

Actually, houses made of wood have a better chance of surviving an earthquake as they can bend and flex. Also, specialty construction like those made with steel beams allows a house to roll with the quake and not suffer too much damage. (From Maritsa in Mr. Harvey's class at the Coeur d'Alene Tribal School in DeSmet)

2: Can we prevent earthquakes?

No, earthquakes on a large scale happen naturally and there is nothing we can do to prevent them. We do, however, generate some very small surface (or near the surface) earthquakes by our activity. (From Skylar in Mrs. Rice's class at Purple Sage Elementary School in Middleton)

3: How many tsunamis can one earthquake trigger?

Only one tsunami will radiate outward from where the earthquake happens. (From Kyle in Mrs. Bryant's class at Horizon Elementary School in Boise)

4: What percentage of earthquakes cause tsunamis?

It's a very small percent because you need perfect conditions for a tsunami to occur. You would need for it to happen where the fault causes the earth to be pushing up or pushing down on the water. If you have plates that slide side by side, the quake will not generate a tsunami. (From Kayla in Mrs. Nicolescus's class at Riverside Elementary School in Boise)

5: Does the moon have moonquakes?

The moon has many quakes. We have placed seismographs, instruments to measure moonquakes, on the moon and discovered that they happen all the time. When a moonquake occurs, the moon actually rings, or shakes, for months because there is no fluid water. (From Joe in Mrs. Schultz's class at Dalton Elementary School in Dalton Gardens)

6: How many aftershocks does an earthquake have?

There may be hundreds or even thousands, depending on how small you measure them. What we do know is that most of the aftershocks happen right afterwards, and then they progressively decline in number as the days and weeks go on. (From Shauna in Mrs. Schultz's class at Dalton Elementary School in Dalton Gardens)

7: How do earthquakes come to be?

There are tectonic plates that try to move past one another. Most earthquakes are located along these plates. Over a long period of time, perhaps hundreds of years, the pressure builds along certain breaks in the rock. There may be no movement and then the pressure builds up and all at once the energy is released to generate the movement of the two tectonic plates past one another. The energy is in the form of seismic waves. (From McKenna in Mrs. Butikofer's class at Hillcrest Elementary School in Boise)

8: Have there been earthquakes in Boise?

We've had lots of earthquakes in Boise and continue to measure them. Near us, Yellowstone is the hottest spot for earthquakes. When there is an earthquake there, it radiates out through Mackey, Challis, and then cuts down through the southeastern part of the state. (From Ava in Mrs. Ramsey's class at Hidden Springs Elementary School in Boise)

9: Could there have been an earthquake bigger than 9.5 before we had the technology to measure earthquakes?

The size of an earthquake has a lot to do with the length of the fault that breaks and how much displacement is on that fault. Everything has to do with the buildup of pressure, and at some point the rocks that we commonly find on this planet cannot sustain the amount of pressure that we find with these very large earthquakes. So we think that earthquakes, like the one in Japan, pretty much are at the maximum of what the earth would produce. (From Taylor and Nate in Mrs. Box's class at Riverside Elementary School in Boise)

10: Why do aftershocks happen and do they happen every time there is an earthquake?

Yes, earthquakes are followed by aftershocks. The initial quake is at one spot, and then a ripple effect, the aftershocks, move outward from there so the entire tectonic plate can move past its neighborhood. (From Megan who is home schooled in Kuna)

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