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More Earth Science Notes Landforms Mountains •A mass of rock rising meters above the surrounding land •Relief vs. Elevation? Types of Mountains Fold Mountain •Usually made mostly of rock folded by compression forces •These are the most and of all mountains Label: Examples of Fold Mountains •Appalachian Mountains • Mountains • • Mountains Fault-Block Mountain •Fault Block Mountain Ranges are cause by a series of Examples of Fault block Mountain ranges • Mountains, CA • , WY Label: •Wasatch Mountains, When the Earth SHAKES: Earthquakes What causes earthquakes? •Volcanic eruptions can cause earthquakes but most earthquakes are caused by Label: •These are often called earthquakes Theory VS. Law •A THEORY is a logical idea that has not been directly but it can often be proved •It is a working set of rules that define a body of •A LAW is observable and can be proven- to a point. However, 100% sure in a Universe as vast as ours is Elastic Rebound Theory •The Theory was first proposed by American geologist Harry after the 1906 San Francisco Earthquake •The sudden release of progressively stored strain in rocks, resulting in along a fault •After the stress becomes too great, the rock layers break, back and forth until eventually coming to a rest •As the rock layers are shaking back and forth they send out waves of vibration called Seismic Waves •“Seismic” always has to do with earthquake activity Seismic Waves are waves of vibration sent out in all directions from the FOCUS •Focus The point where the rock layers break and move •Epicenter The point on the surface, It’s where the greatest . usually occurs Fault Measuring Earthquakes 26 April 1900 – 30 September 1985 Seismograph •A machine that measures earthquake ( ) waves Early Seismograph •Operates on the principle behind Seismogram •The information of earthquake waves Label: The Richter Scale is based on MAGNITUDE Each # is TEN TIMES larger than the # before it… Pennies as an example: Mag. 1 = penny Mag. 2 = pennies Mag 3 = pennies Mag. 4 = pennies Mag. 5 = pennies Mag. 6 = pennies Mag. 7 = pennies Mag. 8 = pennies Mag. 9 = pennies Mag. 10 = pennies (that’s $10 million in pennies!!) Richter Magnitudes Earthquake Effects Less than 3.5 Generally 3.5-5.4 Often felt, Under 6.0 to buildings 6.1-6.9 Destructive to about 7.0-7.9 Major earthquake. Can cause 8 or greater from epicenter . Serious damage for hundreds of km Anatomy of a basic wave • – the highest point on a wave (A, F) • – the lowest point on a wave (D, I) • – the distance between the midpoint & crest or trough • – distance between any two successive points on a wave • - # of vibrations/ second (Hertz) Types of Seismic Waves •Body Waves are waves that travel through the •Surface waves only travel along the Body Waves Primary Waves AKA •Type of Longitudinal Wave •Causes motion •Follows the same direction as the energy transfer •Type of COMPRESSIONAL wave ( •Will travel through ) , or •Travels at: •7.8 – 8.5 kps in •7.2 kps in crust •3.5 kps in crust Secondary Wave AKA •Particle motion is perpendicular to direction of energy transfer •Transverse or Shear Wave •Will travel only through solids •Travels 4 – 5 kps Surface Waves • main types of surface waves: •Love Wave •Rayleigh Wave •Recent evidence shows that L-Waves (gradually disappear) more slowly in older rock (eastern US) and more in younger rock (western US) Love Waves • Love Waves travel less than kps • Move side-to-side; like a • Cause the Seismic Waves with the P-Wave, S-Wave and L-Wave: Triangulation Refraction •Refraction of Zone between about within the Earth degrees & degrees is the Shadow Zone: Focus 105 degrees 145 degrees