Transcript Document
Exploring Earthquakes By: Jordyn Friel and Kylie Edens How many original supercontinents did the continental drift theory assume? Wegener’s theory included one supercontinent called Pangea. What are the major plates that affect the United States? The North American plate and the Gorda plate affect the United States. They form a convergent boundary by colliding into each other’s. Why do you think California has so many earthquakes but Florida doesn’t? California is near a transform boundary called the San Andreas fault, so the two plates grind together creating many earthquakes. Florida doesn’t have many earthquakes. Florida doesn’t have many earthquakes because it is not near a plate boundary like California is. What hazard zone is your home located in? My home is located in the hazard zone of 2-4, which means earthquakes have a very rare chance of happening near my home. What is considered to be the most destructive earthquake? Off the west coast of northern Sumatra there was an earthquake on December 26, 2004 at 7:58 a.m. It killed 277,898 people. The magnitude was 9.1. Divergent Plate Boundary A divergent plate boundary is a zone where two plates move away from each other allowing magma from the mantle to rise up and solidify as “new crust”. Almost all of the Earth’s “new crust” forms at divergent boundaries, but most are not well known because they lie deep beneath the oceans. Convergent Plate Boundary One way 2 plates at a convergent boundary is when one plate pushes the other into the lithosphere and asthenosphere. Where this happens is called a subduction zone. The fate of the colliding plates depends mostly on what type of the lithosphere they are made of. Transform Plate Boundary At a transform boundary the plates grind past each other side by side. This type of boundary separates the North American plate from the Pacific plate along the San Andreas fault. What are tsunamis? Tsunamis are an unusually large sea wave produced by a seaquake or under sea volcanic eruption also called a seismic sea wave. It is formed from tectonic plate activity that occurs in the ocean floor. How fast do tsunamis travel? If a tsunamis is traveling in water depth of 15,000 feet, they can travel upwards of 475mph. Once a tsunamis hits water that is only 100 feet deep, the speed slows to 40mph. What are the 2 types of energy waves created by an earthquake? One type of energy wave is a p wave, which stands for a primary wave. Another type of energy wave is an s wave, which stands for a secondary wave. How do the 2 energy waves differ? P waves move in a compressional motion similar to a slinky. S waves move in a shear motion perpendicular to the direction the wave is traveling, similar to a rope. Which type of energy wave travels faster? P waves would arrive at a seismograph first. That means the p wave travels faster than a s wave. How much more energy is released by a 7.2 quake than a 6.2 quake? A 7.2 earthquake produces 10 times more ground motion than a 6.2 earthquake, but it releases about 32 times more energy. The energy release best indicates the destructive power of an earthquake What applications does seismology have besides measuring the magnitude and location of earthquakes? Seismology also provides a means to monitor for nuclear explosions used to test and build weapons. This is because buried nuclear explosions create seismic waves which can be detected by seismographs. The challenge of modern day seismic monitoring. The challenge of modern day seismic monitoring is to be able to detect very small nuclear explosions anywhere in the world. Where did most of the earthquakes happen last week? Most of the earthquakes that happened last week were in Alaska, California, Puerto Rico and Hawaii. Can scientists predict earthquakes? Scientists can predict where major earthquakes are likely to occur. They also can make general guesses about when earthquakes might occur in a certain area Scientists have more success predicting aftershocks. How do scientists know where an earthquake actually occurred? They use data collected from as many seismograph stations as possible and perform a calculation called “triangulation”. This involves using the p and s waves travel times recorded at each station to find the distance of the earthquake from each seismograph.