EART 2 Lecture Notes - Lecture 11: Asthenosphere, 1906 San Francisco Earthquake, San Andreas Fault
Document Summary
Plates are mosaic of stiff rock masses that move relative to each other on the surface. Earthquakes associated with plate tectonics and plate boundaries. Oldest ocean floor is only 200 million years old. Oldest farthest away from where new floor is created. Old is being recycled in mantle of earth after subduction. To figure out how plates moved more than 200 million years ago. We use continental rocks, which are ~3. 9 bya. Earth"s magnetic field is like a bar magnet with very regular variation in the magnetic field line that vary in a systematic way. Rock pressure direction of latitude of which they were formed. Indicates how rocks have moved how continents have shifted in latitude. Behavior of earth materials depends profoundly on time. Response to forces with different time durations varies. Short impulsive force (e. g. fault slip, explosion) crust/mantle rocks respond as (cid:1445)solid(cid:1446) with (cid:1445)elastic behavior(cid:1446)
