What causes earthquakes 16 November 2018 Do now
What causes earthquakes? • 16 November 2018 • Do now: A ____ fault forms as a result of horizontal compression. a) b) c) d) Blind Normal Strike-slip Reverse
What causes earthquakes? • The San Andreas Fault, a result of horizontal shear, is a ____ fault. a) b) c) d) Blind Normal Strike-slip Reverse
In this unit we will learn about: • The relationship between plate tectonics and earthquakes • How scientists locate and measure earthquakes • The different ways earthquakes result in damage, and why some of them produce so much damage
What causes earthquakes? • Based on our earlier lessons, what causes earthquakes?
What causes earthquakes? • Vibrations in the Earth’s crust • Elastic Rebound Theory: as forces at the fault build up, stress increases. Rocks fracture earthquake; rocks spring back to original shape
How does location on the planet relate to likelihood of earthquakes? • 19 November 2018 • You definitely need your Reference Tables to answer this. (page 11) • Do now: Seismograph station D is 7, 700 kilometers from the epicenter. If the P-wave arrived at this station at 2: 15 p. m. , at approximately what time did the earthquake occur? a) b) c) d) 1: 56 PM 2: 00 PM 2: 04 PM 2: 08 PM 2: 15 PM – 11 min = ? 2: 04 PM Heads up: There will be a Science in the News article due when we return from Thanksgiving break. I will have the worksheet for you tomorrow, and a copy will be posted to my website.
What causes earthquakes? • Energy radiates outward in seismic waves • These stress other rocks which fracture and result in aftershocks • The area where slippage begins is the focus. This is inside the Earth. • The point on the surface directly above the focus is the epicenter • The fault scarp is the small step or offset on the ground surface where one side of a fault has moved vertically with respect to the other.
What causes earthquakes?
Earthquake Focus Location
How does Focus Location Determine Earthquake Strength? • 90% of earthquakes are Shallow-focus • Within 70 km of surface • Result in the most damage • Intermediate (70 -300 km deep) • Deep (300 -650 km deep)
How does location on the planet relate to likelihood of earthquakes? • 20 November 2018 • You definitely need your Reference Tables to answer this. (page 11) • Do now: Seismograph station D is 7, 700 kilometers from the epicenter. If the P-wave arrived at this station at 2: 15 p. m. , when will the S waves arrive? a) b) c) d) 2: 13 PM 2: 09 PM 2: 24 PM 2: 34 PM P arrived @ 2: 15 PM Reminder: There is a Science in the News S arrived 9 minutes later article due when we return from Thanksgiving. Be sure to take a copy of the 2: 15 PM + 9 = 2: 24 PM worksheet from my low desk. Remember the rules regarding appropriate websites and your drawings. This is SITN #2, and the due date is 26 Nov 2018
How does location on the planet relate to likelihood of earthquakes?
What are Major Earthquake Zones? • Pacific Ring of Fire • Mid–Ocean Ridges • Eurasian-Melanesian Belt • European and African/ Indian plates colliding Hot spots
How Likely Is A Major Earthquake In Brooklyn?
What Causes Fault Zones? • Fault Zone: groups of interconnected faults • Typically, at plate boundaries due to stresses when plates: • • Subduct Collide Separate or Rift Slide past each other or Strike Slip or Shearing • San Andreas Fault
Think, Pair, Share • Turn to page 5 in Reference Tables • Do now: There have been recent earthquakes in Nepal, Chile, and Haiti. Based on what we’ve learned and the chart, how can we compare these locations? Haiti Chile Nepal
How do we Detect and Record Earthquakes? • 21 November 2018 • Do now: Seismograph station B recorded the arrival of P-waves at 2: 10 p. m. and the arrival of S-waves at 2: 15 p. m. Approximately how far is station B from the earthquake epicenter? a) b) c) d) 1400 km 2400 km 3400 km 4400 km 2: 15 – 2: 10 = ? 5 min
How do we Detect and Record Earthquakes? • Seismograph • Records vertical motion of the ground • Records horizontal in east-west and north-south • Records as waves on paper or electronically
How do we Detect and Record Earthquakes? • P (primary) waves and S (secondary) waves • P waves are compression waves, rock moves in the direction of the wave; travel through solids & liquids (including Earth’s liquid outer core; ) fastest • S waves are shear or secondary waves, rock moves perpendicularly to the wave; travel only through solids; slower • When these reach the surface, they can be converted to Surface Waves. • Slow moving, like ocean waves on the surface • Rise and fall; VERY destructive
Earthquake Waves
Earthquake Waves
Earthquake Waves
Unit 5: Earthquakes Mr. Ross Brown Brooklyn School for Law and Technology
What causes earthquakes? • 16 November 2018 • Do now: A ____ fault forms as a result of horizontal compression. a) b) c) d) Blind Normal Strike-slip Reverse
What causes earthquakes? • The San Andreas Fault, a result of horizontal shear, is a ____ fault. a) b) c) d) Blind Normal Strike-slip Reverse
In this unit we will learn about: • The relationship between plate tectonics and earthquakes • How scientists locate and measure earthquakes • The different ways earthquakes result in damage, and why some of them produce so much damage
What causes earthquakes? • Based on our earlier lessons, what causes earthquakes?
What causes earthquakes? • Vibrations in the Earth’s crust • Elastic Rebound Theory: as forces at the fault build up, stress increases. Rocks fracture earthquake; rocks spring back to original shape
How does location on the planet relate to likelihood of earthquakes? • 19 November 2018 • You definitely need your Reference Tables to answer this. (page 11) • Do now: Seismograph station D is 7, 700 kilometers from the epicenter. If the P-wave arrived at this station at 2: 15 p. m. , at approximately what time did the earthquake occur? a) b) c) d) 1: 56 PM 2: 00 PM 2: 04 PM 2: 08 PM 2: 15 PM – 11 min = ? 2: 04 PM Heads up: There will be a Science in the News article due when we return from Thanksgiving break. I will have the worksheet for you tomorrow, and a copy will be posted to my website.
What causes earthquakes? • Energy radiates outward in seismic waves • These stress other rocks which fracture and result in aftershocks • The area where slippage begins is the focus. This is inside the Earth. • The point on the surface directly above the focus is the epicenter • The fault scarp is the small step or offset on the ground surface where one side of a fault has moved vertically with respect to the other.
What causes earthquakes?
Earthquake Focus Location
How does Focus Location Determine Earthquake Strength? • 90% of earthquakes are Shallow-focus • Within 70 km of surface • Result in the most damage • Intermediate (70 -300 km deep) • Deep (300 -650 km deep)
How does location on the planet relate to likelihood of earthquakes? • 20 November 2018 • You definitely need your Reference Tables to answer this. (page 11) • Do now: Seismograph station D is 7, 700 kilometers from the epicenter. If the P-wave arrived at this station at 2: 15 p. m. , when will the S waves arrive? a) b) c) d) 2: 13 PM 2: 09 PM 2: 24 PM 2: 34 PM P arrived @ 2: 15 PM Reminder: There is a Science in the News S arrived 9 minutes later article due when we return from Thanksgiving. Be sure to take a copy of the 2: 15 PM + 9 = 2: 24 PM worksheet from my low desk. Remember the rules regarding appropriate websites and your drawings. This is SITN #2, and the due date is 26 Nov 2018
How does location on the planet relate to likelihood of earthquakes?
What are Major Earthquake Zones? • Pacific Ring of Fire • Mid–Ocean Ridges • Eurasian-Melanesian Belt • European and African/ Indian plates colliding Hot spots
How Likely Is A Major Earthquake In Brooklyn?
What Causes Fault Zones? • Fault Zone: groups of interconnected faults • Typically, at plate boundaries due to stresses when plates: • • Subduct Collide Separate or Rift Slide past each other or Strike Slip or Shearing • San Andreas Fault
Think, Pair, Share • Turn to page 5 in Reference Tables • Do now: There have been recent earthquakes in Nepal, Chile, and Haiti. Based on what we’ve learned and the chart, how can we compare these locations? Haiti Chile Nepal
How do we Detect and Record Earthquakes? • 21 November 2018 • Do now: Seismograph station B recorded the arrival of P-waves at 2: 10 p. m. and the arrival of S-waves at 2: 15 p. m. Approximately how far is station B from the earthquake epicenter? a) b) c) d) 1400 km 2400 km 3400 km 4400 km 2: 15 – 2: 10 = ? 5 min
How do we Detect and Record Earthquakes? • Seismograph • Records vertical motion of the ground • Records horizontal in east-west and north-south • Records as waves on paper or electronically
How do we Detect and Record Earthquakes? • P (primary) waves and S (secondary) waves • P waves are compression waves, rock moves in the direction of the wave; travel through solids & liquids (including Earth’s liquid outer core; ) fastest • S waves are shear or secondary waves, rock moves perpendicularly to the wave; travel only through solids; slower • When these reach the surface, they can be converted to Surface Waves. • Slow moving, like ocean waves on the surface • Rise and fall; VERY destructive
Earthquake Waves
Earthquake Waves
Earthquake Waves
How can we locate an earthquake’s epicenter? • 26 November 2018 Kindly place your SITN write-up in the bin. Also, please take a copy of today’s lab. I know some is a little blurry, but you’ll be ok. • Do now: What is the relationship between the velocity of compressional waves (P-waves) and the velocity of shear waves (Swaves) as they travel through the same material? a) P-waves have a greater velocity. b) S-waves have a greater velocity. c) P-waves and S-waves have the same velocity.
How can we locate an earthquake’s epicenter? • 26 November 2018 Kindly place your SITN write-up in the bin. Also, please take a copy of today’s lab. I know some is a little blurry, but you’ll be ok. • Do now: Four seismograph stations receive data from the same earthquake. The table below shows the differences in travel times for the P- and S-waves recorded at each station. Which station is the closest to the epicenter of the earthquake? ØA ØB ØC ØD S wave arrival – P wave arrival distance from epicenter
What causes earthquakes? • 27 November 2018 • This question may require the use of the Earth Science Reference Tables. How far apart are the P-wave and S-wave arrival times for an earthquake with an epicenter that is 6500 km away? a) b) c) d) 6. 5 minutes 8 minutes 10 minutes 18. 5 minutes Kindly take a copy of our lab #7 from my low desk. Reference tables out.
How can we locate an earthquake’s epicenter?
How can we locate an earthquake’s epicenter?
How can we locate an earthquake’s epicenter? B X A C Epicenter
How can we locate an earthquake’s epicenter?
How can we locate an earthquake’s epicenter?
How can we plot location of earthquake epicenter? • 27 November 2018 • Do now: please come up to my low desk and take a copy of Lab #7. • You will be sharing a compass with a partner. One of you must come see me to sign out a compass.
How can we locate an earthquake’s epicenter? • Subtract P wave arrival time from S wave arrival time • Find that difference on the Reference Table
How can we plot location of earthquake epicenter? You are only plotting the locations of earthquakes #1 & #3. • 28 November 2018 • Do now: continue Lab #7. • You will be sharing a compass with a partner. One of you must come see me to sign out a compass.
How can we plot location of earthquake epicenter? • 29 November 2018 • This question may require the use of the Earth Science Reference Tables. How far apart are the P-wave and Swave arrival times for an earthquake with an epicenter that is 5000 km away? a) b) c) d) 6. 5 minutes 8 minutes 10 minutes 18. 5 minutes Kindly take a copy of our lab #8 from my low desk. Reference tables out.
How can we plot location of earthquake epicenter? • 29 November 2018 • Do now: Base your answer to this question on your knowledge of earth science, the Earth Science Reference Tables, and the diagram below. The diagram represents a cross section of the Earth showing the paths of earthquake waves from a single earthquake source. Seismograph stations are located on the Earth's surface at points A through F, and they are all located in the same time zone. What explanation do scientists give for the reason that station F did not receive S-waves? a)The Earth's inner core is so dense that S-waves cannot pass through. b)The Earth's outer core is liquid, which does not allow S-waves to pass. c)S-waves do not have enough energy to pass completely through the Earth. d)S-waves become absorbed by the Earth's crust.
How can we plot location of earthquake epicenter? • 3 December 2018 • We are continuing our work on epicenter location so we can become experts. • All three (3) epicenter labs are due TODAY. Take out any labs you may not have finished. Complete them. • You will be sharing a compass with a partner. One of you must come see me to sign out a compass.
How do Earthquakes Cause Damage? • 4 December 2018 • A P-wave takes 5 minutes to travel from the epicenter of an earthquake to a seismic station. Approximately how many minutes will it take an S-wave to travel that same distance? a) 15 min b) 12 min c) 9 min d) 4 min
How do Earthquakes Cause Damage? • Damage to buildings and roads • Looser soil results in more damage • Mexico City
How do Earthquakes Cause Damage? • Tsunamis • Epicenter on ocean floor • Faulting rise or fall of ocean floor disturbs water • Could trigger underwater landslides
How do Earthquakes Cause Damage?
How do we Measure an Earthquake’s Severity? • 5 December 2018 • Do now: Base your answer to this question on your knowledge of Earth Science and your Earth Science Reference Tables. A strong earthquake that occurs on the ocean floor could result in the formation of: a) b) c) d) a tsunami a delta an El Niño event an ocean current
How do we Measure an Earthquake’s Severity? World's largest earthquake tsunami map: The Chilean earthquake produced a powerful tsunami that traveled at a speed of about 200 miles per hour across the Pacific Ocean. The wave killed 61 people in Hawaii, 138 in Japan, and 32 in the Philippines. The star marks the location of the epicenter, and the numbers on the contour lines are travel times in hours for the wave front. Image by NOAA.
How do we Measure an Earthquake’s Severity? Largest earthquake tsunami damage: An aerial view of damage caused along the coast of Chile by the tsunamis. This scene shows part of a coastal community where homes were torn from their foundations and tossed about by the waves. Damage was near total in these areas. NOAA image by Pierre St. Amand.
How do we Measure an Earthquake’s Severity? Earthquake damage at Valdivia: Photograph of buildings in Valdivia, Chile damaged by the earthquake. This photo shows houses located on an area underlain by fill. They slid downhill when the waterlogged soil beneath them failed. NOAA image by Pierre St. Amand.
How do we Measure an Earthquake’s Severity?
How do we Measure an Earthquake’s Severity? • Magnitude • The measure of energy released or the amount of ground motion • We used to use the Richter scale, now we use Moment Magnitude or Mercalli Scale • Largest ever: 9. 5 on Richter Scale (in Chile in 1960) • Major is 7 or above • An earthquake <2. 5 unlikely to be felt
Richter Scale
Richter Scale
Mercalli Scale Moment Magnitude Scale
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