GEOL 240Lg 1st Edition Lecture 14 Outline of Last Lecture I. Radiometric Dating II. DecayIII. Relative Dating parent solutionIV. Decay Rate V. Layered StructuresVI. CompositionOutline Current Lecture I. Interpreting Seismograms: Just What Happened in that Earthquake, Anyway? II. MapsIII. Diagram of SeismogramsCurrent 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 = aesthosphereSeismograms:Basic element to seismometers is a pendulum. Seismic observatory:short period instruments ( T is about ISAC) to read body waveslong period instruments ( T_> 20 sec) design to receive surface waves-->each one designed has 3 components of ground1)vertical component (measures down motion)- horizontal ( 1 measure NS motion other EW motion)*the temperature at the center of the earth is
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