GEOL 240Lg 1st Edition Lecture 1 Outline Current Lecture I Definition of science II What is a Paradigm III Who is George Mendel IV Introduction to what are Plate Tectonics and Earthquakes V 1960 s Revolution in Earth Science VI Defining edges of Tectonic Plates VII Fault Planes Current Lecture A theory in science is a hypothesis which is what makes science Science is simply taking observations and testing them out like pot shots You conduct many experiments until you reach the point when the hypothesis has much data and is ironed into a theory In science and all encompassing idea or set of practices that define a scientific discipline Humans have been doing this for 10 000 years been doing this in trial and error until Gregor Mendel did his experiments Gregor Mendel 1822 1884 the father of modern genetics He spent his entire life cross breeding peas His hypothesis wasn t accepted during his lifetime His studies helped humanity understand biology Why are we talking about this Because earth sciences went through a similar shift called THE ADVENT OF PLATE TECTONICS In 1960 if you pulled all the scientists in the world all this was ridiculed as nonsense but by 1970 s 99 believe plate tectonics thought this was this right How did we go from thinking this was nonsense to right This is how science is it takes times to be proven right 1965 1970 there was a complete revolution in earth science complete shift in how people were thinking about plate tectonics this revolution explains mountains and everything even volcanoes distribution of volcanoes why we have oceans and why we have continents why are the ocean levels low and continents high It also explains why some floors of the world s oceans are low What s an earthquake It is the sudden slippage of one block of rock past another along a fault A fault is a failure in the rock a crack in the rock What makes it a fault A crack in the rock that had slip of the blocks on either side past each other The sudden slip generates seismic waves The passage of these waves causing the shaking we feel as an earthquake So faults are only there from earthquakes If no earthquakes occur then they are just cracks Earthquakes don t occur just anywhere around the world They occur in very well defined areas Most of earth has very few earthquakes earthquake belts 90 of the energy released in earthquakes around the world is around the Pacific Ocean belts Some of these belts are really narrowly designed Ocean Other belts mostly next to continents are much wider 3rd type of belt are really messy mainly in Southern Asia really wide and spread out Bathymetry underwater photography Bathymetric studies show that these narrow mid ocean earthquake belts correspond to mid ocean undersea mountain chains Wider belts around Pacific Rim Earthquakes extend from near seafloor to as much as 700km depth These earthquakes correspond to oceanic trenches e g Marianas trench Where we are California we only have shallow earthquakes These belts are closely associated with most of the world s volcanoes The point at which an earthquake starts is hypocenter this is when the fault starts slipping These really shallow earthquakes generally don t cause damage We worry about the surface earthquakes Epicenter the point on the surface directly on top of hypocenter Earthquake belts define edges of tectonic plates 1 Eq belts define the edges of about 12 tectonic plates 1 100km thick 2 Thin rigid skin of the earth 3 The plates constitute what we call the lithosphere 4 Rigid lithospheric plates move relative 2 one another above a weak slushy layer called the asthenosphere I All tectonic activities Earthquakes mountains volcanoes occur at boundaries beneath atmospheric plates Tectonic Greek tectos builder I 3 types of plate boundaries Divergent where 2 plates move apart or diverge Convergent where 2 plates move towards each other or converge Transform plates move horizontally past each other accommodate space problems associated with spherical earth FAULT AREN T LINES THEY ARE PLANES