Science Q and A

Molly BoydAnd

Megan Brooker

How many “supercontinents” did the Continental Drift theory assume?

• In 1912 Alfred Wegner’s theory of Continental Drift consisted of one “supercontinent” called Pangea that broke apart about 250 million years ago.

What are the major plates that affect the U.S.?

• The tectonic plates that affect the U.S. are the North American Plate, Juan de Fuca Plate, Pacific Plate and counting Puerto Rico the Carribean Plate.

Why does California have so many earthquakes but Florida doesn’t?

• Florida is sitting on the middle of the North American Plate so it is seismically inactive. California lies on the junction of the Pacific Plate and North American Plate (San Andreas Fault) and when they slip past each other earthquakes happen.

What is considered the most destructive earthquake in history?

• An earthquake in Shensi, China on Jan. 23, 1556 had a magnitude of eight and abt. 830,000 deaths and damage extended as far as 270 mi. from the epicenter.

What are the three basic plate boundaries?

• Divergent: plates go apart in opposite directions.

• Convergent: plates push together.

• Transform: plates slip past each other (ex. San Andreas Fault)

What are tsunami’s?

• An earthquake happens underground which causes a huge wave to come up over the land. On average about 500 mi. which is as fast as a commercial jet.

What are two types of energy waves from an earthquake?

• Primary waves: travel first and go through all three types of matter.

• Secondary waves: come second and only travel through solids, 60% slower than primary waves.

How much more energy is released in a 7.2 than a 6.2 earthquake.

• It releases about 10x more ground motion but 32x more energy.

What applications does seismology have besides

measuring magnitude and location of earthquakes? • It can provide

information on internal structure and state of matter. Also useful in reflection and refraction seismology and geophysical exploration to locate layers of different density.

Where did the most earthquakes happen last week?

• The most earthquakes happened in Alaska last week.

Can scientists predict earthquakes?

• No, and it’s doubtful they ever will because they can only observe from a distance. They also don’t know if there’s a process an earthquake goes through and if it differs with the size of earthquake.

How do scientists know where an earthquake actually

occurred?• They use data from at

least three seismograph stations and perform a calculation called triangulations. This involves using the travel times of primary and secondary waves recorded at each station to find the earthquake’s distance. Once you have enough data you plot circles at the radius and where the circles meet is the epicenter.

CREDITS

Pictures: Molly Boyd

Sound effects: Molly Boyd

Information: Megan Brooker

Emotional support: Megan Brooker

Powerpoint: Megan Brooker and Molly Boyd