Rock n' on Shakey Ground PDF
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Summary
This document details the fundamental concepts of earthquakes, such as defining epicenter, hypocenter, and faults. It explains the causes of earthquakes and how they are measured using seismographs and different wave types like P and S waves. It concludes with an examination of earthquake prediction.
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Rock n’ on Shakey Ground 1. What is an earthquake? a. W hen two blocks of the earth (tectonic plates) suddenly slip past eachother releasing large amounts of energy i. Surface where they slip is called the fault /fault plane b. Locat...
Rock n’ on Shakey Ground 1. What is an earthquake? a. W hen two blocks of the earth (tectonic plates) suddenly slip past eachother releasing large amounts of energy i. Surface where they slip is called the fault /fault plane b. Location below earth’s surface is called hypocenter c. Directly above earth’s surface is called epicenter 2. Define the following terms: Epicenter, Hypocenter(Focus), Fault, Fault Plane . E a picenter - Location above earth’s surface (above starting point of earthquake) b. Hypocenter - Underground focus point of earthquake (location below earth’s surface) c. Fault - Basically like a fracture or a crack between two blocks or parts of the earth d. Fault Plane - plane that represents the fracture surface of a fault. 3. What causes earthquakes and where do they mostly happen? a. T he edges of tectonic plates (plate boundaries) are made up of many faults - most earthquakes occur when one of the plates slides past another i. The plates boundaries are really rough and are always moving 4. How do we measure and record earthquakes? a. Earthquakes are recorded by seismographs i. The recording they make is called a seismogram ii. The base of the seismograph is firmly planted into the ground and a heavy weight hangs freely. iii. When an earthquake causes the ground to shake the base of the seismograph also shakes, but the hanging weight does not. 1. Instead, the spring/string that it is hanging from absorbs all the movement. b. Finally, the difference between the shaking part and the motionless part is what is recorded. 5. What are P Waves, S waves? (use the link below to help you out if you need it. a. P waves - cause the ground to compress and expand, that is, to move back and forth, in the direction of travel. b. S waves - shake the ground in a shearing, or crosswise, motion that is perpendicular to the direction of travel ttps://www.britannica.com/video/rock-vibrations-Earth-earthquake-waves- h P-surface/-218347 6. How are P and S waves comparable to Thunder and Lightning? a. P waves are like lightning and S waves are thunder - The P waves travel faster and shake the ground first, then the S waves follow and shake the ground after. 7. How do scientists locate where the Earthquake is? a. T he arrival times of the P- and S-waves at different seismometers are used to determine the location of the earthquake. 8. How are earthquakes measured? a. T he Richter scale measures the largest wiggle (amplitude) on the recording, but other magnitude scales measure different parts of the earthquake. 9. Can we predict earthquakes? Why or why not? a. W e do not know how, and we do not expect to know how at any time in the foreseeable future. USGS scientists can only calculate the probability that a significant earthquake will occur (shown on our hazard mapping) in a specific area within a certain number of years.
