Quiz 8 (9:30-9:35 AM)

GY 111: Physical Geology

UNIVERSITY OF SOUTH ALABAMA

Lecture 24: Earthquakes

Instructor: Dr. Douglas W. Haywick

Today’s Agenda

Web notes 23: Lab Manual Chapter 7

A) Types of Brittle Deformation B) Types of faults/terminology C) Faults on maps

Faults (Brittle Deformation)

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

More about seismograms shortly, but first… Earthquake magnitude.

Seismic waves are recorded using seismographs. The traces are called seismograms.

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 Effects

(source http://earthquakescanada.nrcan.gc.ca) # per year

(worldwide) Source: USGS

Strength compared to a Magnitude 3

quake

1 Not perceptible to people ? -100

2 1,300,000 -10

3 Often felt, but rarely cause damage. 130,000 --

4 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 1 ¹

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

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)

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

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

Source: http://earthquake.usgs.gov/

Seismicity of Australia, Indonesia and New Zealand: 1990-2000

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/

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

Largest Earthquakes in the World Since 1900

Source: http://earthquake.usgs.gov/regional/world/10_largest_world.php

Seismograms

December 26, 2004 Tsunami

Tsunami Arrival Times (hours:minutes)

Sour

ce: I

OC

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.