GEOL 240Lg 1st Edition Lecture 14 Outline of Last Lecture I Radiometric Dating II Decay III Relative Dating parent solution IV Decay Rate V Layered Structures VI Composition Outline Current Lecture I Interpreting Seismograms Just What Happened in that Earthquake Anyway II Maps III Diagram of Seismograms Current Lecture Between 100 and 200Km in depth temperatures inside earth are almost hot enough to melt ultramatic rock Lithosphere below melting temperatures solid strong aesthenosphere traction moving aesthosphere pulls lithosphere along with it Ridge push hot material swells up at mid oceanic spreading ridges and pushes slab of lithosphere aside core Fe Ni probably some Sulfur outer core is solid composition crust mantle lithosphere weak mantle below lithosphere aesthosphere Seismograms Basic element to seismometers is a pendulum Seismic observatory short period instruments T is about ISAC to read body waves long period instruments T 20 sec design to receive surface waves each one designed has 3 components of ground 1 vertical component measures down motion horizontal 1 measure NS motion other EW motion the temperature at the center of the earth is 7000C
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