Title: GLY 150: Earthquakes and Volcanoes Spring 2005: 030105
1GLY 150 Earthquakes and VolcanoesSpring 2005
03/01/05
1999 Chi-Chi, Taiwan Earthquake
Lecture 12
All from http//www.ceri.memphis.edu/taiwan/day4pi
cs.shtml
2AnnouncementsGLY 150 Earthquakes and Volcanoes
- The next journal assignment is due this Thurs.
If you still have questions regarding the
grading, I have discussed grading criteria in
class and with the TA. If you would like your
journal assignments regraded, please see the TA
(grading criteria specified in your syllabus) - Your next HW assignment is on the web. It is due
next Tuesday, - Instructor office hours have changed to Mon.
200-300 and Wed. 200-300. You can always
make an appoint with me to arrange other times. - Remember, use your texts to supplement the
lecture notes, especially as we start case
studies next week. It will be impossible to
cover all the material in the text but it will
appear on exams and its actually interesting.
3Events this QuarterSpring 2005
Note Some of the eruptions may be ongoing so be
sure to check their current status
4Earthquake MagnitudeThe Amount of Energy Released
http//jove.geol.niu.edu/faculty/fischer/105_info/
105_E_notes/lecture_notes/Earthquakes/EQ_part2.htm
l
5Earthquake MeasurementEnergy Release
- Earthquake magnitude scales are logarithmic such
that a unit increase in magnitude results in a
roughly 32-fold increase in the amount of energy
released during the event - e.g., Richter Magnitude
- Unit increase in magnitude 10x increase in
amplitude of ground shaking - Unit increase in magnitude 32x increase in
energy released
Magnitude Approximate Equivalent TNT Energy
4.0 1010 tons
5.0 31800
tons 6.0
1,010,000 tons 7.0
31,800,000 tons 8.0
1,010,000,000 tons 9.0
31,800,000,000 tons
6Worldwide Seismic Moment ReleaseWhere?
- Most seismic moment/energy release occurs at
subduction zones
http//www.essc.psu.edu/ammon/HTML/Classes/IntroQ
uakes/Notes/earthquake_size.html
7Largest Measured EarthquakesAll Megathrust Events
8Indian-Asian Collisional ZoneHimalayan Range
9Convergent Plate BoundariesContinental Collision
Zones Continent vs. Continent
- Because both are buoyant, neither continental
plate subducts broad areas of high elevation
(large mountain ranges and high plateaus) result
Figure in This Dynamic Earth (http//pubs.usgs.gov
/publications/text/historical.html)
10Supercontinent CyclesContinental Collision
- In part, rock uplifted in a continental
collisional zone comes from sediments deposited
in the ocean basin located between the continents
prior to collision - Rocks in continental collision
- zones are highly deformed
- Magma doesnt reach the
- surface so there is no
- active volcanism
http//jan.ucc.nau.edu/wittke/GLG100/PlateTectoni
cs.html
11India-Asian Collision Zone Faults
- Complexly faulted
- Multiple faults in multiple orientations
- Faults are widely distributed
http//www.brunel.ac.uk/depts/geo/iainsub/studwebp
age/khan/faults-3.jpg
12Formation of the Himalayas and TibetConvergent
Boundary Continental Collision
- Indian subcontinent colliding with Eurasian plate
Both from Dynamic Earth http//pubs.usgs.gov/publ
ications/text/understanding.htmlanchor5798673
13Formation of the Himalayas and TibetConvergent
Boundary Continental Collision
From http//www.pbs.org/wgbh/nova/everest/earth/bi
rthmountains.html
14Formation of the Himalayas and TibetConvergent
Boundary Continental Collision
From http//www.pbs.org/wgbh/nova/everest/earth/bi
rthmountains.html
15Formation of the Himalayas and TibetConvergent
Boundary Continental Collision
From http//www.pbs.org/wgbh/nova/everest/earth/bi
rthmountains.html
16Formation of the Himalayas and TibetConvergent
Boundary Continental Collision
From http//www.pbs.org/wgbh/nova/everest/earth/bi
rthmountains.html
17Formation of the Himalayas and TibetConvergent
Boundary Continental Collision
From http//www.pbs.org/wgbh/nova/everest/earth/bi
rthmountains.html
18Formation of the Himalayas and TibetConvergent
Boundary Continental Collision
- Major shortening and thickening
- Accommodated via thrust faulting
Continental collision is initiated
Mature continental collision zone
Dynamic Earth http//pubs.usgs.gov/publications/t
ext/understanding.htmlanchor5798673
19India-Asian Collision Zone Distribution of
Seismicity
1977-1997 Seismicity
- Seismicity broadly distributed
- Extends great distances from plate boundary
- Localized in some areas, absent in others
http//gldss7.cr.usgs.gov/neis/general/seismicity/
c_asia.html
20Continental Collision ZonesConvergent Boundary
Continental-Continental
- Earthquakes at the interface between the two
plates - Shallow, broadly distributed earthquakes in both
plates due to the intense compression at the
plate boundary
High hazard in some areas, very low hazard in
other areas
http//seismo.ethz.ch/GSHAP/eastasia/
21The India-Asia Collision ZoneConvergent
Boundary Continental-Continental
- Plate boundary interface
- History of large earthquakes
- Many likely seismic gaps near population centers
http//cires.colorado.edu/bilham/HimHazardScience
.html
222000 Republic Day Earthquake, Bhuj, India
- Mw 7.7
- Occurred on shallow thrust fault relatively far
from plate boundary - At least 20,005 killed 166,836 injured
- 339,000 building destroyed 783,000 damaged
- Many roads and bridges damaged in Gujarat
Province - Intraplate earthquake felt over large area
- Seismic waves in Indian subcontinent travel like
seismic waves in eastern U.S.
http//www.asc-india.org/
232000 Republic Day Earthquake, Bhuj, India
- Major hazard collapse of unreinforced masonry
structures, especially in remote villages - In cities, collapses often the result of
improper/illegal construction practices
http//www2.rcep.dpri.kyoto-u.ac.jp/7Emori/India/
photos/
The Cities
The Villages
24Quiz
25Quiz 5 Convergent Boundaries
- (1 point) Tsunamis are generated because
- megathrust earthquakes usually break the surface
on land - subduction zone faults are thought to be freely
slipping at depth - there are shallow earthquakes at subduction zones
- megathrust earthquakes generally break the
surface under the ocean - megathrust earthquakes often produce dead forests
- (1 point) Oceanic-Continent collision zones
- can produce earthquakes with magnitudes above 9
- are not located around the Ring of Fire
- produce broad, extensive areas of deformation
- produce no change in elevation in the overriding
plate - cannot produce tsunamis
- (2 points) Write 2-3 complete sentences
discussing concepts you are having difficulty
with, topics you think are particularly
interesting, specific questions you might have,
or topics you want to hear more about, etc.
26Aleutian Subduction Zone,Alaska
27Convergent Plate BoundariesSubduction Zones
Oceanic vs. Oceanic
- Narrow mountain belts with volcanoes.
- Since they are detached from any continent, these
mountain belts are called island arcs (e.g. a
narrow linear chain of volcanic islands). - The oldest, coldest, densest slab subducts
Figure in This Dynamic Earth (http//pubs.usgs.gov
/publications/text/historical.html)
28Aleutian Arc, AlaskaSeismicity
Different colors represent different depths
29Subduction ZonesBenioff Zones Aleutian Arc
- Note volcanism along island arc
http//geologyindy.byu.edu/faculty/rah/tectonics/S
tudent20Presentations/200020Fall/Brian20Black/a
laskan.htm
30The Aleutian Subduction ZoneConvergent Boundary
Oceanic-Oceanic
http//www.giseis.alaska.edu/Seis/graphics/akseis.
gif
311964 Prince William Sound, Alaska Earthquake
- Mw 9.2
- Triggered major tsunami
- Major damage in Gulf of Alaska
- Lesser damage in Canada and West Coast of United
States (15 killed) - 125 deaths
- 110 from tsunami
- 15 from earthquake
- 311 million in property damage
- Shaking last for 3 minutes
http//gldss7.cr.usgs.gov/neis/eqlists/USA/1964_03
_28.html
32Subduction ZonesDeformation
- Between events
- Thrust boundary is locked (i.e. stuck)
- Coastline is uplifted
- Overriding crust is shortened
- During earthquakes
- Thrust boundary is slipping
- Coastline subsides
- Overriding plate experiences tension
Between Events
Earthquake
331964 Prince William Sound, Alaska Earthquake
- As with all major subduction zone earthquakes,
- Huge areas of land uplifted
- Huge areas of land subsided
http//www.tulane.edu/sanelson/geol204/eqhazards
risks.htm
341964 Prince William Sound, Alaska Earthquake
- Vertical displacements over an area of 520,000
square kilometers - Maximum uplifts of 11.5 meters other areas
subsided up to 2.3 meters - Triggered major tsunami
- Major damage in Gulf of Alaska
- Lesser damage in Canada and West Coast of United
States (15 killed) - Maximum wave height 67 meters
- Minor damage along Gulf Coast of Louisiana and
Texas
Uplifted marine terrace and fault scarp
http//www.ngdc.noaa.gov/seg/mainmeta.shtml also
Fig. 4.21 Pipkin and Trent
351964 Prince William Sound, Alaska
EarthquakeOther Damage
Landslide Damage
- Landslides in Anchorage (120 km from epicenter)
caused major damage - 30 blocks of structures damaged or destroyed
- Schools devastated
- Largest slide 130 acres
- Water, gas, sewer, telephone and electrical
systems disrupted throughout area
(infrastructure) - Fires at Valdez oil terminal
- Liquefaction also a problem
Tsunami Damage
All from http//www.ngdc.noaa.gov/seg/hazard/slide
set/earthquakes/
36Film Clip
The Eruption of Mount Saint Helens
37(No Transcript)
38Bonus Quiz
Is it Spring or Fall Semester?