3/13/2012 1 Earthquakes (ch 13) 1. Why do we care? 2. What is an e-quake? 3. How are they recorded and studied? 4. Where do they occur 5. Magnitude and intensity 6. prediction Why we care? 1. Destruction, injury, death 1906 SanFransisco -- FIRE Earthquakes don’t kill people, buildings do A. Shaking B. Fire C. Falling into cracks/fissures D. Building collapse Seven largest earthquakes Date Location Name Magnitude May 22, 1960 Valdivia, Chile 1960 Valdivia earthquake 9.5 March 27, 1964 Prince William Sound, Alaska, USA 1964 Alaska earthquake 9.2 December 26, 2004 Indian Ocean, Sumatra, Indonesia 2004 Indian Ocean earthquake 9.1–9.3 March 11, 2011 Pacific Ocean, Tōhoku region, Japan 2011 Tōhoku earthquake 9.0 [3][4][5] November 4, 1952 Kamchatka, Russia (then USSR) 1952 Kamchatka earthquakes 9.0 [2] November 25, 1833 Sumatra, Indonesia 1833 Sumatra earthquake 8.8–9.2 (est.) February 27, 2010 Maule, Chile 2010 Chile earthquake 8.8 Seven most deadly earthquakes Deadliest earthquakes[12] Rank Name Date Location Fatalities Magnitude 1 "Shaanxi" January 23, 1556 Shaanxi, China 820,000–830,000 (est.) [13] 8.0 (est.) 2 "Tangshan" July 28, 1976 Tangshan, China 242,419–655,000 7.5–7.8 3 "Haiti" January 12, 2010 Haiti 316,000(Haitian sources) 50,000–92,000 (non- Haitian sources) 7.0 4 "Antioch" May 21, 526 Antioch, Turkey (thenByzantine Empire) 250,000 [15] 7.0 (est.) [16] 5 "Gansu" December 16, 1920 Ningxia–Gansu, China 235,502 [17] 7.8 6 "Indian Ocean" December 26, 2004 Indian Ocean, Sumatra, Indonesia 230,210+ [18][19] 9.1–9.3 7 "Aleppo" October 11, 1138 Aleppo, Syria 230,000 Unknown Just because an earthquake is powerful……... doesn’t mean it is deadly 1. Where and when could earthquakes occur? 2. How big and damaging are they? 3. What do earthquakes tell us about the earth? Left: Photo taken prior to the earthquake. Low income housing- unreinforced masonry. Below: After BBC Magnitude 7.0 HAITI Tuesday, January 12, 2010 at 21:53:09 UTC Haiti 2010: Small earthquake, very deadly
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ch13 equake - University of Colorado Boulderruby.colorado.edu/~smyth/G1010/13EarthquakesEric.pdfGreat Wave off the Coast of Kanagawa, by Hokusai, a famous late eighteenth- and early
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Eric Marti/AP Photo
Earthquakes (ch 13)
1. Why do we care?2. What is an e-quake?3. How are they recorded and studied?4. Where do they occur5. Magnitude and intensity 6. prediction
Why we care?1. Destruction, injury, death
1906 SanFransisco -- FIREEarthquakes don’t kill people, buildings do
A. ShakingB. FireC. Falling into cracks/fissuresD. Building collapse
Seven largest earthquakesDate Location Name Magnitude
May 22, 1960 Valdivia, Chile1960 Valdivia earthquake
9.5
March 27, 1964Prince William Sound, Alaska, USA
1964 Alaska earthquake
9.2
December 26, 2004Indian Ocean, Sumatra, Indonesia
2004 Indian Ocean earthquake
9.1–9.3
March 11, 2011Pacific Ocean, Tōhoku region, Japan
2011 Tōhoku earthquake
9.0[3][4][5]
November 4, 1952Kamchatka, Russia (then USSR)
1952 Kamchatka earthquakes
9.0[2]
November 25, 1833 Sumatra, Indonesia1833 Sumatra earthquake
8.8–9.2 (est.)
February 27, 2010 Maule, Chile2010 Chile earthquake
8.8
Seven most deadly earthquakesDeadliest earthquakes[12]
4 "Antioch" May 21, 526Antioch, Turkey (thenByzantine Empire)
250,000[15] 7.0 (est.)[16]
5 "Gansu"December 16, 1920
Ningxia–Gansu, China 235,502[17] 7.8
6"Indian Ocean"
December 26, 2004
Indian Ocean, Sumatra, Indonesia
230,210+[18][19] 9.1–9.3
7 "Aleppo"October 11, 1138
Aleppo, Syria 230,000 Unknown
Just because an earthquake is powerful……...doesn’t mean it is deadly
1. Where and when could earthquakes occur?2. How big and damaging are they?3. What do earthquakes tell us about the earth?
Left: Photo taken prior to the earthquake. Low income housing- unreinforced masonry.
Below: After
BBC
Magnitude 7.0 HAITITuesday, January 12, 2010 at 21:53:09 UTC
Haiti 2010: Small earthquake, very deadly
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BBC
Magnitude 7.0 HAITITuesday, January 12, 2010 at 21:53:09 UTC
Bike trip along west coast of MexicoWhat hazard did I subject myself to?
December 26, 2004 Indian Ocean tsunami(Sumatra, 2004 earthquake)
Destruction from Dec 26, 2004 Indian Ocean tsunami
Number of deaths = 250,000
Other tsunamisMay, 1782 Taiwan 50,000August, 1883 Indonesia 36,000October, 1707 Japan 30,000June 1896 Japan 27,000
Great Wave off the Coast of Kanagawa, by Hokusai, a famous late eighteenth- and early nineteenth-century Japanese artist.
Tsunami: a Japanese word for "harbor wave.""tsu“ = harbor"nami," = wave
Minimize the danger from tsunamis….
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What is a Tsunami?series of waves generated in water by a disturbance that vertically displaces the water column.
What processes generate tsunamis?A) EarthquakesB) landslides C) volcanic eruptionsD) impact of cosmic bodies E) All of the above
Why we care?2. Key earth process
Mountain building Earth structure
Seismology: study of earthquakes
1. Where and when could earthquakes occur?2. How big and damaging are they?3. What do earthquakes tell us about the earth?
2. What is an earthquake?
Earthquake:
Earthquake: vibration of Earth produced by rapid release of energy
Waves (energy) radiate in all directions from focusfocus is a point on a fault plane
Epicenter is point on the surface above focus
FOCUS
Earthquake depths: typically 0-100 km
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Why are most earthquakes within 100 km of Earth’s surface
Environment Temperature Pressure Behavior
surface low low
Greater depths
high high
This earthquake occurred on the subduction zone plate boundary where the oceanic Nazca Plate subducts beneath the South American Plate.
The two plates are converging at a rate of about 8 cm/yr.
Earthquakes are products of plate motion:
Nazca Plate
South American Plate
UNAVCO
Regional TectonicsThis map shows the rates and directions of motion of the Cocos, Pacific, and Caribbean plates with respect to the North American Plate. The Caribbean Plate moves eastward at a rate of 2 cm/year.
Pacific
PlateCocos Plate
North American Plate
Caribbean Plate
Transform Plate Boundaries (yellow lines)
Divergent Plate Boundaries (red lines)
Earthquakes are products of plate motion:
Earthquakes are products of plate motion:WHY is there an instantaneous release of energy?
1. In many places, plates do not slowly grind past each other
2. Instead: there is no motion across a fault for some interval
strain accumulates, and is then released during an earthquake
Elastic rebound during earthquake
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2 types of faults
2. Strike-slip: movement primarily along strike of the fault surface
1. Dip-slip: movement primarily along DIP of the fault surface
Vertical displacement horizontal displacement
Map of deformation: Dec 2004 Sumatra earthquak
From: NASA Natural Hazards web page
3. Measuring EarthquakesSeismometers and Seismographs