CE442 Geotechnical Earthquake Engineering
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Questions and Answers

What is the period of a wave?

  • The frequency of a wave
  • The number of seconds it takes for a building to naturally vibrate back and forth
  • The number of waves that pass through a point in one second
  • The amount of time it takes one wave cycle to pass a given point (correct)

    • What is the relationship between frequency and period of a wave?

  • Frequency is unrelated to period
  • Frequency is directly proportional to period
  • Frequency is equal to period
  • Frequency is inversely proportional to period (correct)

    • What happens when the period of ground motion matches the natural resonance of a building?

  • The building becomes more stable and less prone to damage
  • The building is completely unaffected by the ground motion
  • The building undergoes the largest oscillations possible and suffers the greatest damage (correct)
  • The building's natural resonance changes to match the period of ground motion

    • What type of soil deposits is characterized by high amplitude and low frequency?

    <p>Soft sediment</p> Signup and view all the answers

    What is the effect of attenuation on seismic waves?

    <p>It reduces the energy of seismic waves at certain frequencies</p> Signup and view all the answers

    What is an example of an area where attenuation of seismic waves is likely to occur?

    <p>Bedrock area</p> Signup and view all the answers

    What is the effect of amplification on seismic waves?

    <p>It increases the energy of seismic waves at certain frequencies</p> Signup and view all the answers

    What is the unit of frequency?

    <p>Hertz (Hz)</p> Signup and view all the answers

    What type of plate boundary is characterized by two tectonic plates sliding past each other horizontally?

    <p>Transform boundary</p> Signup and view all the answers

    What is the process called when one plate is forced beneath the other at a convergent plate boundary?

    <p>Subduction</p> Signup and view all the answers

    What is the thinnest outer solid shell of the Earth?

    <p>Crust</p> Signup and view all the answers

    What is the layer of the Earth composed of hot, dense ultrabasic igneous rock in a plastic state?

    <p>Asthenosphere</p> Signup and view all the answers

    What is the temperature of the crust?

    <p>25°C</p> Signup and view all the answers

    What is the density of the inner core?

    <p>12,000 to 13,000 kg/m3</p> Signup and view all the answers

    What is an example of a transform boundary?

    <p>San Andreas Fault</p> Signup and view all the answers

    What is the depth of the outer core?

    <p>2,900 km to 5,150 km</p> Signup and view all the answers

    What causes convection currents to develop in the viscous mantle?

    <p>The high pressure and temperature gradients between the crust and the core</p> Signup and view all the answers

    What is the primary cause of fault creation?

    <p>The movement of Earth's lithospheric plates</p> Signup and view all the answers

    What is the term for the point of generation of an earthquake?

    <p>Hypocenter</p> Signup and view all the answers

    Which of the following faults is located in Northern Philippines?

    <p>East Zambales Fault</p> Signup and view all the answers

    What is the result of convection currents in the mantle?

    <p>The circulation of the Earth's mass, with hot molten lava coming out and cool rock mass going down</p> Signup and view all the answers

    What type of forces are responsible for the movement of the Earth's lithospheric plates?

    <p>Tectonic forces</p> Signup and view all the answers

    What is the term for the fracture in the Earth's crust where movement has occurred?

    <p>Fault</p> Signup and view all the answers

    Which of the following is NOT an active fault in Northern Philippines?

    <p>Masbate Fault</p> Signup and view all the answers

    What is the main goal of Earthquake Engineering?

    <p>To develop methods to reduce the effects of earthquakes on people and their environment</p> Signup and view all the answers

    According to the historical records, which country has the oldest records of earthquakes?

    <p>China</p> Signup and view all the answers

    What is the economic threat of earthquakes?

    <p>Billions of dollars of public infrastructure are at risk</p> Signup and view all the answers

    What is the magnitude of the Luzon Earthquake that occurred in 1990?

    <p>Ms 7.8</p> Signup and view all the answers

    What is the reality of earthquakes?

    <p>They cannot be prevented, but their effects can be mitigated</p> Signup and view all the answers

    What is the principal type of earthquake damage that refers to the harm inflicted on buildings and infrastructure?

    <p>Structural damage</p> Signup and view all the answers

    Which of the following earthquakes is NOT a destructive earthquake in the Philippines?

    <p>Baguio Earthquake</p> Signup and view all the answers

    What is the interdisciplinary nature of Earthquake Engineering?

    <p>Combines aspects of geology, seismology, geotechnical engineering, structural engineering, risk analysis, and other technical fields</p> Signup and view all the answers

    What is the primary focus of geotechnical earthquake engineering?

    <p>Design and construction of projects to resist the effect of earthquakes</p> Signup and view all the answers

    What may occur if liquefaction happens at a site?

    <p>Complete loss of soil shear strength</p> Signup and view all the answers

    What is the significance of human experience with earthquakes?

    <p>Human experience with earthquakes is brief compared to the millions of years over which earthquakes have occurred</p> Signup and view all the answers

    What is one of the tasks of a geotechnical engineer in earthquake engineering?

    <p>Investigating the possibility of liquefaction at the site</p> Signup and view all the answers

    What is the global phenomenon of earthquakes?

    <p>Earthquakes occur globally, affecting both developed and undeveloped areas</p> Signup and view all the answers

    What is the magnitude of the Bohol Earthquake that occurred in 2013?

    <p>Ms 7.2</p> Signup and view all the answers

    What do geotechnical engineers need to understand in order to perform earthquake engineering?

    <p>Geology, seismology, and earthquake engineering</p> Signup and view all the answers

    What is one of the considerations of geotechnical engineers when designing foundations for earthquakes?

    <p>Bearing capacity and allowable soil bearing pressures</p> Signup and view all the answers

    Study Notes

    Introduction to Geotechnical Earthquake Engineering

    • Earthquake Engineering aims to understand and mitigate the impacts of earthquakes on people and their environment.
    • It is an interdisciplinary field that combines geology, seismology, geotechnical engineering, structural engineering, risk analysis, and other technical fields.

    Historical Perspective

    • Earthquake records date back 3000 years in China, nearly 1600 years in Japan and Eastern Mediterranean, and about 350 years in the United States.
    • Hundreds of millions of people worldwide live with significant earthquake risk, posing an economic threat to local, regional, and national economies.
    • Earthquakes cannot be prevented, but the goal is to mitigate the effects of strong shaking to reduce loss of life, injuries, and damage.

    Principal Types of Earthquake Damage

    • Structural damage refers to the harm inflicted on buildings, bridges, roads, and other infrastructure due to earthquake forces.
    • Seismic hazard includes ground shakings, which can cause damage to structures depending on construction quality, materials, and design.

    Seismic Hazard

    • Ground shakings can cause damage to structures, and the damage can vary greatly depending on the construction quality, materials, and design.
    • Period (T) is the time it takes for one wave cycle to pass a given point, and Frequency (F) is the number of waves that pass through a point in one second.
    • Frequency = 1 Hz (cycle per second), and the natural period of a building is the number of seconds it takes for the building to naturally vibrate back and forth.
    • If the period of ground motion matches the natural resonance of a building, it will undergo the largest oscillations possible and suffer the greatest damage.
    • Soft sediment (soil deposits) can cause high amplitude, low frequency ground shakings, while hard bedrock can cause low amplitude, high frequency ground shakings.
    • Attenuation and amplification of seismic waves can occur due to soil conditions, reducing or increasing the energy of seismic waves at certain frequencies.

    Destructive Earthquakes in the Philippines

    • List of destructive earthquakes in the Philippines, including Ragay Gulf Earthquake (1973), Casiguran Earthquake (1968), and others.

    Geotechnical Earthquake Engineering

    • Geotechnical earthquake engineering deals with the design and construction of projects to resist earthquake effects.
    • It requires an understanding of geology, seismology, and earthquake engineering.
    • Geotechnical engineers may need to investigate liquefaction, calculate settlement, check foundation design, and evaluate slope stability and lateral deformation.

    Plate Boundaries

    • Three types of plate boundaries: transform, convergent, and divergent.
    • Transform boundaries are regions where two tectonic plates slide past each other horizontally, causing earthquakes.
    • Convergent plate boundaries are regions where two tectonic plates are moving towards each other, leading to subduction, mountain formation, earthquakes, and volcanic activity.

    Interiors of the Earth

    • The earth is composed of a sequence of shells or layers called geospheres, with the heaviest forming the core.
    • The lithosphere (crust) is the thinnest outer solid shell, with a density of 1500 kg/m3 and a temperature of about 25°C.
    • The asthenosphere (mantle) is 2685 km thick, surrounding the core, with a density of 5000-6000 kg/m3.
    • The outer core is a molten layer of iron and nickel beneath the mantle, extending from 2,900 km to 5,150 km depth.
    • The inner core is a solid, dense region at the center of the earth, extending from 5,150 km to the core at 6,371 km depth.

    Faults

    • Faults are created primarily through tectonic forces and the movement of Earth's lithospheric plates.
    • Faults are fractures in the Earth's crust where movement has occurred, resulting in displacement of the rock on either side.
    • The point of generation of an earthquake is known as the focus, center, or hypocenter.
    • List of active faults in the Philippines, including East Zambales Fault, Iba Fault, and others.

    Fundamental Fault Mechanics

    • (No specific notes provided for this topic)

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    Introduction to Geotechnical Earthquake Engineering, understanding and mitigating the impacts of earthquakes on people and their environment.

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