GEOG 2300 1st Edition Lecture 37Outline of Last Lecture I. Earth’s StructureII. Plate TectonicsIII. Plate BoundariesOutline of Current Lecture I. Plate BoundariesII. EarthquakesCurrent LectureI. Plate BoundariesA. Transform (lateral) plate contact: two plates sliding past one another at different ways, is accompanied by frequent earthquakes, ex: San Andreas FaultB. Which of these geographic locations is not a convergent plate margin? Hawaiiwhere a mantle hotspot is causing volcanismII. EarthquakesA. Movement along a plate, fault or point of weaknessB. Greater the movement, the greater the magnitude of the earthquakeC. Occur daily in hundreds of places throughout the world, most are slight and only noticeable on seismographsD. Focus: origin of earthquakeE. Epicenter: the point above the focus on earth’s surfaceF. May be foreshocks and aftershocks, all come from same epicenter, rarely some form of prediction (not reliable)G. 80% occur on the Circum-Pacific Belt, also Trans-Eurasian Belt, fewer still at mid-ocean ridges, intraplate earthquakes (very few and poorly understood)H. Most earthquakes in the U.S. happen in Alaska (Aleutians) and on the San Andreas FaultI. Richter Scale: 0-8+, logarithmic – magnitude of 4 is 10 times bigger than a magnitude 3 and 100 times bigger than a magnitude 2, >8 – 1 annually, 7-7.9 – 18 annuallyJ. Magnitude 5 equals a small atom bomb, 800 of 5-5.9 earthquakes annuallyK. Largest earthquake recorded: Chile – 9.5 magnitude in 1960These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.L. Moment Magnitude: takes into account fault slip, area ruptured and materials faulted, used by scientists more nowM. Mercalli: measures intensity as felt at the surface, descriptive, dependent on local soils, rocks, soil water content that determine how the earthquake is experienced, I – XII
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