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#1 Introduction

January 8, 2003

Fumio Yamazakiyamazaki@ait.ac.th

http://www.sce.ait.ac.th/people/faculty/~yamazakiSTE/SCE, AIT.

CE03.98NSoil Dynamics and Earthquake Engineering

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Course Outline (1)1. Introduction

1.1 Earthquakes 1.2 Consequences of Earthquakes

2. Engineering Seismology2.1 Mechanism of Earthquakes2.2 Seismic Waves2.3 Earthquake Magnitude and Seismic Intensity2.4 Seismometers and Seismic Observation2.5 Tsunamis

3. Seismic Ground Motion3.1 Characteristics of Seismic Ground Motion3.2 Fourier Spectrum3.3 Response Spectrum3.4 Attenuation Relations and Effects of Soil Conditions3.5 Microtremor Observation

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Course Outline (2)4. Seismic Hazard and Seismic Risk

4.1 Seismic Hazard Analysis 4.2 Damage Assessment

5. Dynamic Soil Properties5.1 Measurement of Dynamic Soil Properties5.2 Stress-Strain Behaviors

6. Wave Propagation and Ground Response Analysis6.1 Wave Propagation 6.2 One-Dimensional Ground Response Analysis

7. Liquefaction and Slope Stability 7.1 Liquefaction 7.2 Slope Stability

By Prof. F. Yamazaki

By Prof. P.K. Basudhar

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Class Schedule1) 8 January Lecture: Introduction, Engineering Seismology

(1)2) 15 January Lecture: Engineering Seismology (2) 3) 22 January Lecture: Seismic Ground Motion (1) 4) 29 January Lecture: Seismic Ground Motion (2) 5) 5 February Lecture: Seismic Hazard and Seismic Risk

12 February Midterm Exam6) 19 February Lecture:7) 26 February Lecture:8) 5 March Lecture:9) 12 March Lecture:10) 19 March Lecture:11) 26 March Lecture:

2 April Final Exam

To be announced

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Grading System

The Final grade will be computed according to the following weight distribution: Mid-Term Exam 40%Final Exam 40%Assignments 20%

Closed-book examinations are given both in the mid-term and finals.

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References

Textbook:Lecture Notes (PPT), available on the AIT Web site

Reference Book:S. L. Krammer: Geotechnical Earthquake Engineering,

Prentice Hall, 1996

Reference Web Page:For seismology, http://earthquake.usgs.gov/

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What is an earthquake?

http://earthquake.usgs.gov/image_glossary/

Seismogram: A seismogram is a record written by a seismograph in response to ground motions produced by an earthquake, explosion, or other ground-motion sources

Earthquake: Earthquake is a term used to describe both sudden slip on a fault, and the resulting ground shaking and radiated seismic energycaused by the slip, or by volcanic or magmatic activity, or other sudden stress changes in the earth.

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Basic earthquake termsHypocenter (Focus): The hypocenter is the point within the earth where an earthquake rupture starts.

Epicenter: The epicenter is the point on the earth's surface vertically above the hypocenter.

Magnitude: The magnitude is a number that characterizes the relative size of an earthquake.

http://earthquake.usgs.gov/image_glossary/

Focal Depth: The focal depth refers to the depth of an earthquake hypocenter.

Fault Plane: The fault plane is the planar (flat) surface along which there is slip during an earthquake.

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Where do earthquakes occur ?http://neic.usgs.gov/neis/general/seismicity/world.html

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Ring of Fire(the Circum-Pacific

belt )

The "Ring of Fire“ is the zone of earthquakes surrounding the Pacific Ocean, about 90% of the world's earthquakes occur there. The next most seismic region (5-6% of earthquakes) is the Alpide belt (extends from Mediterranean region, eastward through Turkey, Iran, and northern India.

http://earthquake.usgs.gov/image_glossary/

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RegionalSeismicity

http://neic.usgs.gov/neis/general/seismicity/seismicity.html 12

Plate Tectonics and Earthquakes

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Earthquake Hazard Map

GLOBAL SEISMICHAZARDASSESSMENTPROGRAM

http://seismo.ethz.ch/gshap/14

Earthquake Hazard and RiskEarthquake hazard:Earthquake hazard is anything associated with an earthquake that may affect the normal activities of people. This includes surface faulting, ground shaking, landslides, liquefaction, tectonic deformation, tsunamis, and seiches.

Earthquake risk:Earthquake risk is the probable damage, and number of people that are expected to be hurt or killed if a likely earthquake on a particular fault occurs.

Hazard map

http://earthquake.usgs.gov/image_glossary/

Seismicity of USA 1977 - 1997

http://neic.usgs.gov/neis/general/seismicity/us.html

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1.2 Consequences of EarthquakesGeological hazard

surface faulting, landslides, liquefaction

Tsunamis

Structural damagesbuildings, bridges, lifelines (roads, water systems)

Fires

Human casualty

Socio-economic impacts

Nature(Hazard

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Built Environment

Social World(Risk)

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Fault Rupture in the 1999 Chi-Chi,

Taiwan EQ

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Urban Area Rural Housing

The Gujarat, India EQ on January 26, 2001The Gujarat, India EQ on January 26, 2001

Ms=7.5

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Bridges and Buildings after the 1995 Kobe EQ

MJ=7.2

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Railways after the Kobe EQ

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Damage to Lifelines and Fire Following EQthe 1995 Kobe EQthe 1994 Northridge EQ

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Sand boils and water spoutingGround subsidence Loss of bearing capacityFloating up of underground structuresLateral spreads

Liquefaction

The 1964 Niigata EQ, Japan

Ground failures associated with liquefaction

Beforeearthquake During

liquefactionDuring

earthquake Afterearthquake

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Sand boil and settlement in Kobe Port Island after the Kobe EQ

Uplift of a manhole due to liquefaction in the 1993 Kushiro-Oki EQ

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Overturned building inAdpazari, Turkey in the 1999 Kocaeli EQ

A building in Dagupan, Philippines after the 1990 Luzon EQ

Loss of bearing capacity

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Okushiri Island after the 1993 Hokkaido-Nansei-Oki EQ

RC structure remain A burned boat. Cause of fire?

Complete devastation….

Tsunami disaster

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2. Engineering Seismology

2.1 Mechanism of Earthquakes

2.2 Seismic Waves

2.3 Earthquake Magnitude and Seismic Intensity

2.4 Seismometers and Seismic Observation

2.5 Tsunamis

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Elastic Rebound Theory - Reid 1910

http://www.seismo.unr.edu/ftp/pub/louie/class/100/seismic-waves.html

An earthquake is caused by the rebound of elastically strained rock; From the observation of 1906 San Francisco EQ

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Plate Tectonics is the theory supported by a wide range of evidence that considers the earth's crust and upper mantle to be composed of several large, thin, relatively rigid plates that move relative to one another.

Plate Tectonics

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Crust, Mantle and LithosphereThe crust is the outermost major layer of the earth, ranging from about 10 to 65 km in thickness worldwide. The uppermost 15-35 km of crust is brittle enough to produce earthquakes.

The mantle is the part of the earth's interior between the metallic outer core and the crust.

The lithosphere is the outer solid part of the earth, including the crust and uppermost mantle. The lithosphere is about 100 kmthick.The lithosphere below the crust is brittle enough at some locations to produce earthquakes by faulting, such as within asubducted oceanic plate.

http://earthquake.usgs.gov/image_glossary/

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History of the earth

http://pubs.usgs.gov/publications/text/historical.html

Before the advent of plate tectonics, some people already believed that the present-day continents were the fragmented pieces of preexisting larger landmasses. The diagrams below show the break-up of thesupercontinent Pangaea (meaning "all lands" in Greek).

theory of continental drift

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Earth’s 14 lithosheric plates and their movementsConvergence plate boundary: subduction zone etc.Divergence plate boundary: Plates diverges at mid-ocean ridgesTransform fault: Plates move laterally each other

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An oceanic spreading ridge is the fracture zone along the ocean bottom where molten mantle material comes to the surface, thus creating new crust. This fracture can be seen beneath the ocean as a line of ridges that form as molten rock reaches the ocean bottom and solidifies.An oceanic trench is a linear depression of the sea floor caused by the subduction of one plate under another.

Crustal movements and plate boundaries

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Three types of plate convergence

33Dip Slip (normal or thrust) Strike Slip (right or left lateral)

Four basic types of faults

Fault: A fault is a fracture along which the blocks of crust on either side have moved relative to one another parallel to the fracture.

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Thrust

Normal

Strike-slip faults are vertical (or nearly vertical) fractures where the blocks have mostly moved horizontally. If the block opposite an observer looking across the fault moves to the right, the slip style is termed right lateral; if the block moves to the left, the motion is termed left lateral.

Dip-slip faults are inclined fractures where the blocks have mostly shifted vertically. If the rock mass above an inclined fault moves down, the fault is termed normal, whereas if the rock above the fault moves up, the fault is termed reverse (or thrust). Oblique-slip faults have significant components of both slip styles.

Strike-slip

Oblique-slip faults: Oblique-slip faulting suggests both dip-slip faulting and strike-slip faulting. It is caused by a combination of shearing and tension or compressional forces, e.g., left-lateral normal fault.

Oblique-slip

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Mw=7.5

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Pacific-North American Plate Boundary

The San Andreas Fault

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San Andreas fault

1906 San Francisco EQM7.7-7.9Rupture L =470 km

1989 Loma Prieta EQM7.0 Rupture L = 40 km

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Neodani Fault, Japan1891

1996

A large intra-plate active fault, caused the 1891 Nobi EQ (M=8.0)

http://research.kahaku.go.jp/rikou/namazu/04nobi/noubi.html

Dv= 6mDh= 4m

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Dip: Dip is the angle that a planar geologic surface (for example, a fault) is inclined from the horizontal.

Strike: The strike is the trend or bearing, relative to north, of the line defined by the intersection of a planar geologic surface (for example, a fault or a bed) and a horizontal surface such as the ground.

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Focal Mechanism

http://quake.wr.usgs.gov/recenteqs/beachball.htm

Fault plane solution: A fault plane solution is a way of showing the fault and the direction of slipon it from an earthquake, using circles with two intersecting curves that look like beach balls. Also called a focal-mechanism solution.

T: Tension axis P: Pressure axis

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Asperity: An asperity is an area on a fault that is stuck. The earthquake rupture usually begins at an asperity.

Directivity: Directivity is an effect of a fault rupturing whereby earthquake ground motion in the direction of rupture propagation is more severe than that in other directions from the earthquake source.

Shake Map of the 1994 Northridge earthquake shows the result of rupture directivity toward the north.

Slip: Slip is the relative displacement of formerly adjacent points on opposite sides of a fault, measured on the fault surface.

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Blind thrust fault: A blind thrust fault is a thrust fault that does not rupture all the way up to the surface so there is no evidence of it on the ground. It is "buried" under the uppermost layers of rock in the crust. (e.g. the 1994 Northridge EQ)

Surface faulting: Surface faulting is displacement that reaches the earth's surface during slip along a fault. Commonly occurs with shallow earthquakes, those with an epicenter less than 20 km. Surface faulting also may accompany aseismic creep or natural or man-induced subsidence.

The 1990 Luzon EQ

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http://quake.wr.usgs.gov/info/faultmaps/

Historic: Refers to the period for which historical records are available (approximately the past 200 years in California and Nevada).

Holocene: Refers to a period of time between the present and 10,000 years before present. Faults of this age are commonly considered active.

Active Fault: An active fault is a fault that is likely to have another earthquake sometime in the future. Faults are commonly considered to be active if they have moved one or more times in the last 10,000 years.

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Source Regions of the Destructive Earthquakes in Japan (1885-1999, Depths of 100 km or less)

Inter-plate EQs and Intra-plate EQs

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Distribution of Active Faults in Japan

Active Faults for the Fundamental Survey

1995-200598 fault zones

More than 1,500

A class: Average slip of 1-10 m per 1,000 years B class: Average slip of 10-100cm per 1,000 yearsC class: Average slip of 1-10cm per 1,000 years

Number of active faults in JapanA class: 100, B class=750, C class=450 46

Active Fault Surveys

Topographical survey(field survey, air photos)

Trenching

Underground structure survey (seismic reflection)

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Valley Valley Fault Fault

ManilaManilaTrenchTrench

Philippine Philippine Fault ZoneFault Zone

Satellite SAR Image and FaultsSatellite SAR Image and Faults

Active Faults in Metro Manila

Alabat Is.

Cabalete Is.

Mauban

Atimonan

Lopez

GumacaUnisan