UNIVERSITY OF SOUTH ALABAMA
GY 111: Physical Geology
Lecture 25: Agents of
Metamorphism
Instructor: Dr. Douglas W. Haywick
Last Time…
Earthquakes
A) Seismic waves and the Earth's interior
B) Earthquake intensity and magnitude
C) Seismographs and locating earthquake epicenters
on maps
D) Case Studies (Indonesia)
Seismic Waves
P and S-waves are called body waves because they travel through
the Earth.
P-waves travel through all media and are the fastest (4+ km/s)
S-waves cannot pass through liquids and are slower (3+ km/s)
Seismographs
Seismic waves are recorded
using seismographs.
The traces are called
seismograms.
More about seismograms shortly, but
first… Earthquake magnitude.
Earthquake Magnitude
Modified Richter Scale
Magnitude
1
Effects
(source http://earthquakescanada.nrcan.gc.ca)
Not perceptible to people
2
3
Often felt, but rarely cause damage.
4
# per year
(worldwide)
Source:
USGS
Strength
compared to a
Magnitude 3
quake
?
-100
1,300,000
-10
130,000
--
13,000
10
5
At most slight damage to well-designed buildings. Can
cause major damage to poorly constructed buildings
over small regions.
1300
100
6
Can cause damage to poorly constructed buildings and
other structures in areas up to about 100 kilometers
across where people live. Substantial deaths, especially
if epicenter is in a major city
150
1000
7
"Major" earthquake. Can cause serious damage over
larger areas.
20
10,000
8
"Great" earthquake. Can cause serious damage and
loss of life in areas several hundred kilometers across.
1
100,000
9
Rare great earthquake. Can cause major damage over a
large region over 1000 km across.
<1
1,000,000
10
Impossible unless you make bad movies
10,000,000
Earthquake Magnitude
For the modified Richter
scale method, you need to
measure the amplitude,
but also take into account
the distance from the
earthquake epicenter
Earthquakes
Earthquakes In the USA
?
Death 101
The worst earthquakes
(as far as death is
concerned)
More on this one shortly
Date
Location
Deaths
Magnitude
Jan. 23, 1556
Shansi, China
830,000
~8
July 27, 1976
Tangshan, China
255,0001
7.5
Aug. 9, 1138
Aleppo, Syria
230,000
n.a.
Dec. 26, 2004
off west coast of northern Sumatra
225,000+
9.0
Dec. 22, 8562
Damghan, Iran
200,000
n.a.
May 22, 1927
near Xining, Tsinghai, China
200,000
7.9
Dec. 16, 1920
Gansu, China
200,000
7.8
March 23, 8932
Ardabil, Iran
150,000
n.a.
Sept. 1, 1923
Kwanto, Japan
143,000
7.9
Oct. 5, 1948
Ashgabat, Turkmenistan, USSR
110,000
7.3
Dec. 28, 1908
Messina, Italy
70,000–
100,0003
7.2
Sept. 1290
Chihli, China
100,000
n.a.
Oct. 8, 2005
Pakistan
80,361
7.6
Nov. 1667
Shemakha, Caucasia
80,000
n.a.
Nov. 18, 1727
Tabriz, Iran
77,000
n.a.
Dec. 25, 1932
Gansu, China
70,000
7.6
Nov. 1, 1755
Lisbon, Portugal
70,000
8.7
May 31, 1970
Peru
66,000
7.9
May 30, 1935
Quetta, Pakistan
30,000–
60,000
7.5
Locating Epicenters on maps
Fact: P- and S- waves travel at different speeds through the
Earth so the interval between their separate arrival times can
be used to estimate distance.
Locating Epicenters on maps
You need at least 3
seismograph stations to
locate an epicenter
Locating Epicenters on maps
You need at least 3
seismograph stations to
locate an epicenter
Locating Epicenters on maps
You need at least 3
seismograph stations to
locate an epicenter
Today’s Agenda
Metamorphism 1
1.Indonesian Earthquake (finish last lecture)
2.Agents of Metamorphism
3. Types of metamorphism
4. Hydrothermal fluids (webnotes only)
Web notes: 25
Indonesia, December 26, 2004
Seismicity of Australia, Indonesia and New Zealand: 1990-2000
Source: http://earthquake.usgs.gov/
Indonesia Geopolitical Map
Source: http://earthquake.usgs.gov/
Indonesia Tectonic Map
Source: http://earthquake.usgs.gov/
Indonesia Seismicity Map
Source: http://earthquake.usgs.gov/
Largest Earthquakes in
the World Since 1900
Location
Date UTC
Magnitude
Coordinates
Reference
1.
Chile
1960 05 22
9.5
-38.24
-73.05
Kanamori, 1977
2.
Prince William Sound, Alaska
1964 03 28
9.2
61.02
-147.65
Kanamori, 1977
3.
West Coast of Northern Sumatra
2004 12 26
9.1
3.30
95.78
PDE
4.
Kamchatka
1952 11 04
9.0
52.76
160.06
Kanamori, 1977
5.
Off the Coast of Ecuador
1906 01 31
8.8
1.0
-81.5
Kanamori, 1977
6.
Rat Islands, Alaska
1965 02 04
8.7
51.21
178.50
Kanamori, 1977
7.
Northern Sumatra, Indonesia
2005 03 28
8.6
2.08
97.01
PDE
8.
Andreanof Islands, Alaska
1957 03 09
8.6
51.56
-175.39
Johnson, 1994
9.
Assam - Tibet
1950 08 15
8.6
28.5
96.5
Kanamori, 1977
10.
Kuril Islands
1963 10 13
8.5
44.9
149.6
Kanamori, 1977
11.
Banda Sea, Indonesia
1938 02 01
8.5
-5.05
131.62
Kanamori, 1977
12.
Kamchatka
1923 02 03
8.5
54.0
161.0
Kanamori, 1988
Updated 2006 May 02
Source: http://earthquake.usgs.gov/regional/world/10_largest_world.php
Seismograms
December 26, 2004
Tsunami
Source: IOC
Tsunami Arrival Times (hours:minutes)
The Aftermath
230,000? dead
Whole villages
washed away
Coastlines
permanently
changed
Source: http://wcatwc.arh.noaa.gov
IOC ICG/ITSU
“Early” Warning
System
SEISMOGRAPHIC NETWORK
Agents of Metamorphism….
….but first a word from our sponsor:
The Rock Cycle
The Rock Cycle
The Rock Cycle
Igneous
Loop
Metamorphic
Loop
Sedimentary
Loop
Metamorphism
Metamorphism: a solid state change (recrystallization)
of a parent rock by physical “agents” using operating
deep within the interior of the Earth.
Shale (Parent Rock)
Slate (Metamorphic Rock)
Metamorphism
Agents of Metamorphism
1. Heat (25˚C to 800˚C; up to
the point of melting)
Geothermal Gradient: the increase in
ambient temperature with depth.
15 to 30°C/km under stable continental
rocks
200°C/km under mid oceanic ridges
http://www.geo.umn.edu/courses/1001/Summer_Session/MeltingVsDepth.jpg
Metamorphism
Agents of Metamorphism
1. Heat (25˚C to 800˚C; up to
the point of melting)
2. Pressure (1 bar to 12 kbars)
1 bar = 1 atmosphere
12 kbar = 12,000 atmospheres
http://www.geol.ucsb.edu/faculty/hacker/geo102C/lectures/hydrostat.jpg
Metamorphism
Agents of Metamorphism
1. Heat (25˚C to 800˚C; up to
the point of melting)
2. Pressure (1 bar to 12 kbars)
3. Chemically active fluids
(AKA hot water)
http://news-service.stanford.edu/news/2005
Types of Metamorphism
Regional (heat and pressure)
Associated with convergent
plate boundaries
http://www.indiana.edu/~geol105/images/gaia_chapter_5/regmeta.jpg
Types of Metamorphism
Regional (heat and pressure)
Isograds vs Isotherms
Types of Metamorphism
 Contact (heat only)
Metamorphic
aureole
Metamorphic aureoles
Types of Metamorphism
 Contact (heat only)
Metamorphic aureoles
Types of Metamorphism
 Cataclastic (pressure only)
Mylonites
Shear zones
http://www.cliffshade.com/colorado/homestake/hsz01.jpg
Types of Metamorphism
 Cataclastic (pressure only)
http://instruct.uwo.ca/earth-sci/200a-001/03dymet.gif
Today’s Homework
1.
Assignment number 4 (due Thursday)
2. Quiz Thursday
3. Rock/mineral photo Assignment (due Friday November 20)
4. GY 302 mineral poster show (Tues Nov 24th, 1-3 PM)
BONUS
Next Time
1.
Regional metamorphism
GY 111: Physical Geology
Lecture 25: Introduction to Metamorphism
Instructor: Dr. Doug Haywick
dhaywick@southalabama.edu
This is a free open access lecture, but not for commercial purposes.
For personal use only.