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

Transcription

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

2 UNIVERSITY OF SOUTH ALABAMA GY 111: Physical Geology Lecture 24: Earthquakes Instructor: Dr. Douglas W. Haywick

3 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

4 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

5 Brittle Deformation Fractures are irregularly spaced cracks that cut across rocks

6 Brittle Deformation Joints are regularly spaced and parallel fractures that result from tension. Columnar jointing is caused by cooling Chalk Board

7 Faults are fractures that involve movement. Brittle Deformation

8 Fault Terminology All faults share some features. All active faults are subject to earthquakes Chalk Board

9 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

10 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

11 Strike Slip Faults (Right Lateral) Faults on Maps

12 Normal Faults Faults on Maps

13 Faults on Maps There is a special class of reverse fault that is common in mountain belts Thrust Faults

14 The Canadian Rockies are one of the best places to see thrust faults Faults on Maps

15 Trust faults usually occur in multiples (like in the Rockies) leading to complex geological maps Faults on Maps

16 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

17 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)

18 Seismic waves are recorded using seismographs. Seismographs

19 Seismographs Seismic waves are recorded using seismographs. The traces are called seismograms. More about seismograms shortly, but first Earthquake magnitude.

20 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)

21 Earthquake Magnitude

22 Earthquake Magnitude The Modified Mercalli Intensity Scale is most useful for historical earthquakes, but is subject to perception errors.

23 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

24 Earthquake Magnitude You need to measure the amplitude, but also take into account the distance from the earthquake epicenter

25 Earthquake Magnitude

26 Earthquake Magnitude Magnitude Effects (source # per year (worldwide) Source: USGS 1 Not perceptible to people? ,300, Often felt, but rarely cause damage. 130, , At most slight damage to well-designed buildings. Can cause major damage to poorly constructed buildings over small regions. 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 7 "Major" earthquake. Can cause serious damage over larger areas. 8 "Great" earthquake. Can cause serious damage and loss of life in areas several hundred kilometers across. 9 Rare great earthquake. Can cause major damage over a large region over 1000 km across , ,000 Strength compared to a Magnitude 3 quake <1 1,000, Impossible unless you make bad movies 10,000,000

27 Earthquakes

28 Earthquakes In the USA ( )

29 Earthquakes In the USA?

30 Earthquakes In the USA Three earthquakes (all above 9) hit the New Madrid area from Their cause is still debated.

31 Death 101: The Earthquake Edition Woodcut; New Madrid 1812? Source:

32 Death 101: The Earthquake Edition San Francisco, 1906

33 Death 101: The Earthquake Edition Magnitude vs. Ground Motion and Energy Magnitude Average Annually ¹ ² ² ² ,000 (estimated) 130,000 (estimated) 1,300,000 (estimated) ¹ Based on observations since ² Based on observations since Source:

34 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, Aug. 9, 1138 Aleppo, Syria 230,000 n.a. Dec. 26, 2004 off west coast of northern Sumatra 225, Dec. 22, Damghan, Iran 200,000 n.a. May 22, 1927 near Xining, Tsinghai, China 200, Dec. 16, 1920 Gansu, China 200, March 23, Ardabil, Iran 150,000 n.a. Sept. 1, 1923 Kwanto, Japan 143, Oct. 5, 1948 Ashgabat, Turkmenistan, USSR 110, Dec. 28, 1908 Messina, Italy 70, ,000 3 Sept Chihli, China 100,000 n.a. Oct. 8, 2005 Pakistan 80, Nov Shemakha, Caucasia 80,000 n.a. Nov. 18, 1727 Tabriz, Iran 77,000 n.a. Dec. 25, 1932 Gansu, China 70, Nov. 1, 1755 Lisbon, Portugal 70, May 31, 1970 Peru 66, May 30, 1935 Quetta, Pakistan 30,000 60,

35 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, Aug. 9, 1138 Aleppo, Syria 230,000 n.a. Dec. 26, 2004 off west coast of northern Sumatra 225, Dec. 22, Damghan, Iran 200,000 n.a. May 22, 1927 near Xining, Tsinghai, China 200, Dec. 16, 1920 Gansu, China 200, March 23, Ardabil, Iran 150,000 n.a. Sept. 1, 1923 Kwanto, Japan 143, Oct. 5, 1948 Ashgabat, Turkmenistan, USSR 110, Dec. 28, 1908 Messina, Italy 70, ,000 3 Sept Chihli, China 100,000 n.a. Oct. 8, 2005 Pakistan 80, Nov Shemakha, Caucasia 80,000 n.a. Nov. 18, 1727 Tabriz, Iran 77,000 n.a. Dec. 25, 1932 Gansu, China 70, Nov. 1, 1755 Lisbon, Portugal 70, May 31, 1970 Peru 66, May 30, 1935 Quetta, Pakistan 30,000 60,

36 Locating Epicenters on maps

37 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.

38 Locating Epicenters on maps You need at least 3 seismograph stations

39 Locating Epicenters on maps You need at least 3 seismograph stations to locate an epicenter

40 Locating Epicenters on maps You need at least 3 seismograph stations to locate an epicenter

41 Locating Epicenters on maps You need at least 3 seismograph stations to locate an epicenter

42 Locating Epicenters on maps You need at least 3 seismograph stations to locate an epicenter

43 Locating Epicenters on maps You need at least 3 seismograph stations to locate an epicenter

44 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

45 Indonesia, December 26, 2004

46 Seismicity of Australia, Indonesia and New Zealand: Source:

47 Indonesia Seismicity Map Source:

48 Indonesia Geopolitical Map Source:

49 Indonesia Tectonic Map Source:

50 Number of Earthquakes per Year (Mag 5 and higher), All Depths Source:

51 Largest Earthquakes in the World Since 1900 Location Date UTC Magnitude Coordinates Reference 1. Chile Kanamori, Prince William Sound, Alaska Kanamori, West Coast of Northern Sumatra PDE 4. Kamchatka Kanamori, Off the Coast of Ecuador Kanamori, Rat Islands, Alaska Kanamori, Northern Sumatra, Indonesia PDE 8. Andreanof Islands, Alaska Johnson, Assam - Tibet Kanamori, Kuril Islands Kanamori, Banda Sea, Indonesia Kanamori, Kamchatka Kanamori, 1988 Updated 2006 May 02 Source:

52 Seismograms

53

54 December 26, 2004 Tsunami

55 Source: IOC Tsunami Arrival Times (hours:minutes)

56 The Aftermath 230,000? dead

57 Whole villages washed away

58 Coastlines permanently changed

59 Source:

60 IOC ICG/ITSU Early Warning System

61 SEISMOGRAPHIC NETWORK

62 Today s Homework 1. Photography Assignment 2. Assignment 4 Next Time Agents of Metamorphism

63 GY 111: Physical Geology Lecture 24: Earthquakes Instructor: Dr. Doug Haywick This is a free open access lecture, but not for commercial purposes. For personal use only.