GLY 101 1st Edition Lecture 18 Outline of Last LectureI.What Causes Rock to DeformIII. Folds: Rock Structures formed by Ductile DeformationIV. Faults and Joints: Rock Structures formed by Brittle Deformation Outline of Current Lecture II. xWhat Is an Earthquake? III. Faults and EarthquakesIV.Study of Earthquake wavesCurrent LectureI. What Is an Earthquake?- an earthquake is ground shaking caused by the sudden and rapid movement of one block of rock of rock slipping past another.-the location where slippage starts is the focus or hypocenter- the surface directly above the hypocenter is the epicenter- large earthquakes release huge amounts of stored up energy as seismic waves- seismic waves are a form of energy that causes shaking - H.F. Reid conducted a landmark study following the 1906 San Francisco earthquake- strong earthquakes are followed by numerous earthquakes of lesser magnitude called aftershocks - aftershock happens when the crust along a fault surface is adjusting to the displacement caused by the main shock- After the 2010 Haiti earthquake the U.S. Geological Survey counted 60 aftershocksThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.- foreshocks happen before the major earthquakeIII. Faults and Earthquakes- the slippage that occurs along faults can be explained by the plate tectonics theory- plate tectonics theory states that large slabs of Earth’s lithosphere are continually grinding past one another- faults associated with plate boundaries are the source of most large earthquakes- the three basic types of faults are normal, reverse, and strike- slip- normal faulting is common but not associated with earth quakes- reverse faults are associated with convergent plate boundaries- plate boundary between a subducting slab of oceanic lithosphere and the overlying plate is called a mega thrust fault- strike slip faults are the result of shear stresses and exhibit mainly horizontal slip that result in large segments on earth’s crust to grind past each other-large strike slip faults are called transform faults when they form plate boundaries- a fault creep shows slow and gradual displacement & occurs without the accumulation of strainIV. The Study of earthquake waves- the study of earthquake waves is called seismology - the earliest known instrument was invented by Zhang Heng- the records from seismographs provide information about seismic waves and their nature, these records are called seismograms-surface waves travel in the rock layers just below earth’s surface- other wave types travel through earth;s interior and are called body waves- body waves are divided int two types: primary (p) waves, and secondary (s) waves-(p) waves push/pull or compress/stretch & (s) waves shake- p waves arrive first, then s waves, and finally surface waves-two types of surface waves: 1. causes earth’s surface and anything resting upon it to move 2. causes earth’s materials to move side to