EARTHSC 1151 Study Guide - Midterm Guide: List Of Internet Phenomena, Merca, Oceanic Crust
12 Dec 2015
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Most earthquakes occur near convergent margins along the pacific north west coast and along the aleutians, and to the transform margin in california. Cascadia subduction zone small plates subducting under north america. Probably not, since subducting lithosphere is so young. Thrust faults uplift mountains in transverse ranges. Blind thrust faults do not reach surface, difficult to detect. Trenching - reading the shallow geology to infer where and when eqs have occurred. Paleo seismology and seismic risk analysis: obtain dates of prehistoric earthquakes from radioactive carbon. Ohio (ashtabula township) began pumping industrial waste liquids underground in 1986 earthquakes began in 1987, up to magnitude 4. 5 pressurized fluids flow from well and encounter faults, add stress to cause earthquake (lubricate faults?) Dam earthquakes (oroville, california) construction of dam and filling of reservoir triggered earthquakes water from reservoir seeps into ground at pressure and triggers earthquakes on faults. Also, weight of reservoir water stresses crust and triggers earthquakes (isostasy)
