Quiz 8 (9:30-9:35 AM)
UNIVERSITY OF SOUTH ALABAMA
GY 111: Physical
Geology
Lecture 24: Earthquakes
Instructor: Dr. Douglas W. Haywick
Today’s Agenda
Faults (Brittle Deformation)
A) Types of Brittle Deformation
B) Types of faults/terminology
C) Faults on maps
Web notes 23:
Lab Manual Chapter 7
Mechanical Behavior of Rocks
Near-surface rocks that are under low T-P conditions behave as
brittle material:
– Fault fracture (slippage)
– Joint fracture (no slippage)
Deep rocks under elevated T-P conditions behave as ductile
material:
– Folding
Brittle Deformation
Fractures are
irregularly spaced
cracks that cut
across rocks
http://roamingretirees.wordpress.com/category/state-parksrecreation-areas/
Brittle Deformation
Joints are regularly
spaced and parallel
fractures that result
from tension.
Columnar jointing
is caused by
cooling
Chalk Board
Brittle Deformation
Faults are fractures
that involve
movement.
Fault Terminology
All faults share some
features.
All active faults are
subject to earthquakes
Chalk Board
Fault Terminology
Dip Slip Faults are subdivided
into two types based upon the
sense of motion along the fault
plane and the type of stress
involved
Tension = Normal Fault
Compression = Reverse Fault
Fault Terminology
Strike Slip Faults are also
subdivided into two types based
upon the sense of motion along
the fault plane.
Shear = Strike Slip Fault
Left Lateral Strike Slip Fault
Right Lateral Strike Slip Fault
Faults on Maps
Strike Slip Faults
(Right Lateral)
Faults on Maps
Normal Faults
Faults on Maps
There is a special class of reverse fault that is common in mountain
belts
Thrust Faults
Faults on Maps
The Canadian Rockies
are one of the best places
to see thrust faults
Faults on Maps
Trust faults usually
occur in multiples (like
in the Rockies) leading
to complex geological
maps
Today’s Agenda
Earthquakes
A) Earthquake intensity and magnitude
B) Seismographs
C) Locating earthquake epicenters on maps (Ass 4)
D) Case Studies
Web notes 24:
GY 111 Lab Manual Chapter 7
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.
Seismographs
Seismic waves are recorded
using seismographs.
The traces are called
seismograms.
More about seismograms shortly, but
first… Earthquake magnitude.
Earthquake Magnitude
The “intensity” of an earthquake can be measure through one of
two ways.
1) A “people” method: Modified Mercalli Intensity Scale (I to XII)
2) A geophysical method: Modified Richter Scale (1 to 10)
Earthquake Magnitude
Earthquake Magnitude
The Modified Mercalli Intensity Scale is most useful for
historical earthquakes, but is subject to perception errors.
Earthquake Magnitude
The Modified Richter Scale uses geophysical information
recorded from seismographs.
You need to measure the
amplitude, but also take into
account the distance from
the earthquake epicenter
Earthquake Magnitude
You need to measure the
amplitude, but also take
into account the distance
from the earthquake
epicenter
Earthquake Magnitude
Earthquake Magnitude
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
Earthquakes
Earthquakes In the USA (1973-2002)
Earthquakes In the USA
?
Earthquakes In the USA
Three earthquakes (all above 9) hit the New Madrid area
from 1812-1813. Their cause is still debated.
Death 101: The Earthquake Edition
Woodcut; New Madrid 1812?
Source: http://quake.wr.usgs.gov/prepare/factsheets/NewMadrid/Woodcut.gif
Death 101: The Earthquake Edition
San Francisco, 1906
Death 101: The Earthquake Edition
Magnitude vs. Ground Motion and Energy
Magnitude
Average
Annually
8 - 10
1¹
7 - 7.9
17 ²
6 - 6.9
134 ²
5 - 5.9
1319 ²
4 - 4.9
13,000
(estimated)
3 - 3.9
130,000
(estimated)
2 - 2.9
1,300,000
(estimated)
¹ Based on observations since
1900.
² Based on observations since
1990.
Source: http://neic.usgs.gov/neis/eqlists
Death 101
The worst earthquakes
(as far as death is
concerned)
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
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
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
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
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
Weird Earthquake Stuff
1) Japanese video coverage of the Kobe 1993 earthquake
2) New Zealand 1933 observations
3) Near death experiences in New Zealand earthquakes
4) Liquefaction and building failures (Japan, 1960)
5) California bridge collapses (1974, 1994)
6) Nuclear power plant issues (2010)
Chalk Board
Indonesia, December 26, 2004
Seismicity of Australia, Indonesia and New Zealand: 1990-2000
Source: http://earthquake.usgs.gov/
Indonesia Seismicity Map
Source: http://earthquake.usgs.gov/
Indonesia Geopolitical Map
Source: http://earthquake.usgs.gov/
Indonesia Tectonic Map
Source: http://earthquake.usgs.gov/
Number of Earthquakes per Year (Mag 5
and higher), All Depths
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
Today’s Homework
1. Photography Assignment
2. Assignment 4
Next Time
Agents of Metamorphism
GY 111: Physical Geology
Lecture 24: Earthquakes
Instructor: Dr. Doug Haywick
dhaywick@southalabama.edu
This is a free open access lecture, but not for commercial purposes.
For personal use only.