12.2 and 12.3 Notes Studying Earthquakes & Earthquakes and society Sections 12.2 & 12.3 · seismology - study of earthquakes and seismic waves · seismographs - instrument that records earthquake waves produce seismograms (tracing of earthquake motion) the larger the zig zags the bigger the earthquake Recording Earthquakes Locating an Earthquake · uses the arrival times of P and S waves · longer lag time indicates an earthquake farther away · lag-time graph shows relationship between P & S wave travel time and epicenter distance 1 MATA: What type of wave(s) are used to determine the location of an earthquake? A P waves B surface waves C S waves D body waves E Love waves Click for quick animation · today, computers perform complex calculations to locate epicenter · before computers, 3 seismograph recordings were needed to locate epicenter radius of circle = distance from station to epicenter point where all circles intersect indicates epicenter Locating an Earthquake Magnitude · total am. of energy released during an earthquake · determined by measuring the amount of ground motion caused by an earthquake · moment magnitude - uses fault size and distance that fault blocks move to determine magnitude larger the number, stronger the earthquake · largest recorded earthquake = 9.5 · 2.5 and lower not usually felt by humans
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12.2 and 12.3 Notes
Studying Earthquakes & Earthquakes and society
Sections 12.2 & 12.3
· seismology - study of earthquakes and seismic waves· seismographs - instrument that records earthquake waves
produce seismograms (tracing of earthquake motion)the larger the zig zags the bigger the earthquake
Recording Earthquakes
Locating an Earthquake· uses the arrival times of P and S waves· longer lag time indicates an earthquake farther away· lag-time graph shows relationship between P & S wave travel time and epicenter distance
1 MATA: What type of wave(s) are used to determine the location of an earthquake?
A P waves
B surface waves
C S waves
D body waves
E Love waves
Click for quick animation
· today, computers perform complex calculations to locate epicenter· before computers, 3 seismograph recordings were needed to locate epicenter
radius of circle = distance from station to epicenter
point where all circles intersect indicates epicenter
Locating an Earthquake Magnitude· total am. of energy released during an earthquake· determined by measuring the amount of ground motion caused by an earthquake· moment magnitude - uses fault size and distance that fault blocks move to determine magnitude
larger the number, stronger the earthquake· largest recorded earthquake = 9.5· 2.5 and lower not usually felt by humans
12.2 and 12.3 Notes
· amount of damage caused by an earthquake· earthquake's intensity depends on it
1. magnitude2. distance between epicenter and affected area3. local geology4. duration5. human infrastructure
· measured on modified Mercalli scale (Roman numerals I-XII)
Intensity 2 ___________ is the study of earthquakes.
A Intensity
B Magnitude
C Lag-time
D Seismology
3 Which of the following does NOT influence the intensity of an earthquake?
A duration of earthquake
B distance between fault and focus
C magnitude
D human infrastructure
E local geology
Click for Japan tsunami
Destruction of Quakes· depends on magnitude and proximity to a populated area· structural damage
intensity, duration of vibration, type of ground beneath building, design or structure· tsunamis (large ocean waves generated by quakes)
sudden drop or rise in ocean floor or underwater landslideincrease in height as they approach shore
· fire/explosion (broken power or gas lines)· landslides (triggered by vibrations)· flooding (broken dams/levies)
4 True or false. The bigger the quake and closer it is to a city the more destructive it might be.
True
False
Earthquake Safety· before
be prepared· during
stay calmindoors - stand in doorway or under a
desk/table, stay away from windows and heavy furniture
car - stop the car in a safe place· after
be cautiouswear closed toe shoes
12.2 and 12.3 Notes
Predicting Earthquakes· NO reliable way· methods of prediction
1. seismic gaps - zones of low earthquake activity2. foreshocks - little earthquakes before big ones3. changes in rocks - tilting, strain, cracks4. monitor natural gas seepage from strained or