EPS 20 Lecture Notes - Lecture 5: North American Plate, Radiocarbon Dating, Pacific Plate
26 Apr 2016
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Document Summary
A fracture in rock, with movement across it. Active faults will likely move in the future because it has recently moved. Active if moved in the last 11,000 years. Earthquake fault zone is within 50 feet of a mapped fault (special building projects) Amount of offset can be seen by markers. How earthquakes work: stress builds up due to tectonic plates moving past one another, friction along the fault prevents slip, elastic deformation instead, stress exceeds rupture strength, fault slips aka earthquakes. Released in an earthquake and strain builds up slowly again . Dig trenches in river channels and use radio-carbon dating to determine when the channel was active. Measure total offset by taking oldest material from oldest channel. So, in the case of the wallace creek there is a total offset of 130 meters and the old- est material is 3800 years. So the slip rate= 130/3800= 3. 4 centimeters per year.
