EARTHQUAKES
A.Sudden vibration of the earth caused by release of energyB.Most earthquakes are generated by movement along faultC. Focus-area insdie the earth where the energy is released1.Shallow focus earthquakes-occur less than 40 miles within the earth2. Deep focus earthquakes- occur greaer than 180 miles within the earthD. Epicenter-location on Earths surface directly above the focus E.Foreshocks-smaller earthquakes that preced a larger earthquakeF. Aftershocks-smaller earthquakes that follow a large earthquakeG.Elastic Rebound Theory1. Rocks along an active fault plane stick2.Rocks on either side of fault slowly bend and store energy3.Eventually internal strength of rocks along fault plane are exceeded and they rupture4.Rocks on either side of fault plane "snap back" to their original position, releasing energy that radiates all directions
Seismology
A. STUDY OF EARTHQUAKE WAVESB.TYPES OF SEISMOGRAPHS1. Vertical motion detector2. Horizontal motion detectorC. SEISMORGRAM-seismograph record
EARTHQUAKE WAVES
A. BODY WAVES-move through the Earths interior1.P-wavesa. Arrive first at seismic recording stationb. Rocks expand and contract as waves move through themc. Travel through solids, liquids, and gases2. S-wavesa. Arrive second at a recording stationb. Shake rocks at right angles to their direction of travelc. Travel only through solidsB.SURFACE WAVES-travel along Earths surface1. Cause much of the damage associaed with earthquakes
Locating Earthquakes
look at page 101!!!
Measuring Earthquakes
A. MODIFIED MERCALLI INTENSITY SCALE1.Measures damage done and peoples reactions to earthquakes2. Used primarily by insurace companiesB. RICHTER SCALE1. Magnitude scale that measures amplitude of the largest wave recorded2. The difference between any two numberes represents a 32 fold increase in energy released
Damages Associated with Earthquakes
A. GROUND SHAKING- causes the most damage and loss of life1. Geology and ground shakinga. Solid bedrock-structures built on solid bedrock generally suffer less damageb. Liquefaction- water saturated sediment may lose cohesion when shaken and flow2. Building materials and ground shakinga. Wood and reinforced concrete tend to be more flexibleb. Brick and unreinforced concrete tend to crumbleB. TSUNAMI1. Series of waves generated by earthquakes , volcanic eruptions, underwater landslides2. Are 3-6 feet high when travel across ocean3. As waves enter shallow water, they slow and begin to build4.Tsunami may come onshore as waves or as rapid rise in waterC. LANDSLIDES- vibrations frm earthquakes may generate mass wasting eventsD. GROUND SUBSIDENCE-ground surface may subside due to movement along faultsE. FIRE