Understanding Earthquakes: Seismic Waves, Identification, and Locations
This article delves into the science of earthquakes, explaining how they transform stored energy into kinetic energy through seismic waves. It covers essential topics such as the focus and epicenter of earthquakes, the difference between primary (P) and secondary (S) waves, and the scales used to measure magnitude and destruction. Readers will learn about seismographs and how seismologists determine the distance to an epicenter. The piece also highlights key earthquake-prone areas, including the Ring of Fire, mid-ocean ridges, and the Eurasian-Melanesian Mountain Belt.
Understanding Earthquakes: Seismic Waves, Identification, and Locations
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Presentation Transcript
Earthquakes and waves Energy Transformation in the form of Seismic Waves
New Island • < http://www.bbc.co.uk/go/em/fr/-/news/world-asia-24272552 >
Earthquakes • Earthquakes transfer stored energy into kinetic energy in form of seismic waves. • Waves are an oscillation or vibration that transfers energy
Earthquake Identification and Location • Earthquakes are located and identified by their focus, epicenter and magnitude • Focus: The point where the fracture in rock occurs, (under ground). • Epicenter: The point, on land, directly above the focus point. • Magnitude: The amount of energy or destruction that has been released/caused
Magnitude • Richter Scale: Measures the total amount of energy released by the earthquake. • Magnitude 7 or greater is a major quake • Magnitude 6 or less is a minor quake • Magnitude 2 or less is a micro quake or tremor
Magnitude Continued • 2. Mercalli Scale: Measures the degree of destruction that has been caused. This is a scale that is far more subjective in nature. Mercalli scale rates on a scale of I – XII (I) is little damage and (XII) is extreme destruction
Seismic Waves Primary or P waves Secondary or S waves Slower moving wave Arrives at recording stations after the P wave Moves in an up and down way Cause buildings to shake Travels through solid material only • Fastest moving seismic wave • Arrive at recording stations first • Moves in a spring like way • Travel through both liquid and solid material
Primary and Secondary Waves • P waves oscillate through compression and expansion, in the same direction of movement • S waves oscillate in a direction that is perpendicular to direction of movement
L-Waves • L waves are also known as surface waves • They are the slowest but most destructive waves • They are the waves that cause surface rolling
Which is the fastest moving seismic wave? • Which seismic wave is most destructive?
Distance to Epicenter • Seismologists determine the distance to the earthquake’s epicenter through analyzing the difference in arrival times at the recording station. • When arrival times are close, with little difference, the distance to the epicenter is very small. • The greater the difference in arrival times, the further away the epicenter is • Use information from 3 recording stations to triangulate the location
Location of Earthquakes • 3 major locations where earthquakes occur Ring of Fire
Earthquake location continued Mid ocean ridges
Earthquake locations continued The Eurasian-Melanesian Mountain Belt
What is the different plate activity at each of the locations where seismic activity takes place?Ring of Fire, Mid-Ocean Ridge,and Eurasian-MelanesianMountain Range
