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Questions and Answers
What type of boundary occurs when two tectonic plates move apart from each other?
What type of boundary occurs when two tectonic plates move apart from each other?
Which term describes the activity at mid-ocean ridges?
Which term describes the activity at mid-ocean ridges?
What is typically the result of a convergent boundary interaction?
What is typically the result of a convergent boundary interaction?
What is created when a continent experiences divergence, resulting in a continental rift?
What is created when a continent experiences divergence, resulting in a continental rift?
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What geological feature is often formed at a transform boundary?
What geological feature is often formed at a transform boundary?
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What do the regions between tectonic belts typically exhibit?
What do the regions between tectonic belts typically exhibit?
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What phenomenon describes the early stage of seafloor spreading that resulted in the formation of the Red Sea?
What phenomenon describes the early stage of seafloor spreading that resulted in the formation of the Red Sea?
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What occurs frequently at divergent boundaries, particularly at mid-ocean ridges?
What occurs frequently at divergent boundaries, particularly at mid-ocean ridges?
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What was the intensity of the 1968 Casiguran earthquake on the Rossi-Forel Intensity Scale?
What was the intensity of the 1968 Casiguran earthquake on the Rossi-Forel Intensity Scale?
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What major event occurred to a building during the Casiguran earthquake?
What major event occurred to a building during the Casiguran earthquake?
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What geological feature is involved in the 2004 earthquake described?
What geological feature is involved in the 2004 earthquake described?
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What role does the Engineering Geology and GeoHazard Assessment (EGGA) process play?
What role does the Engineering Geology and GeoHazard Assessment (EGGA) process play?
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What does the Richter scale measure?
What does the Richter scale measure?
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What generally happens to a seismic wave when it passes into a material that causes it to slow down?
What generally happens to a seismic wave when it passes into a material that causes it to slow down?
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A magnitude increase of 1 on the Richter scale indicates how much increase in amplitude of seismic waves?
A magnitude increase of 1 on the Richter scale indicates how much increase in amplitude of seismic waves?
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What is the purpose of the DENR AO2000-28 issued by the Philippine government?
What is the purpose of the DENR AO2000-28 issued by the Philippine government?
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What effect does a seismic ray have when it passes from a fast material to a slower one?
What effect does a seismic ray have when it passes from a fast material to a slower one?
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What does a Modified Mercalli Intensity scale value of 'I' signify?
What does a Modified Mercalli Intensity scale value of 'I' signify?
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What was the main consequence of the Casiguran earthquake in relation to infrastructure?
What was the main consequence of the Casiguran earthquake in relation to infrastructure?
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Which earthquake is known to have occurred in 1964 in Alaska and had a magnitude of 9.2?
Which earthquake is known to have occurred in 1964 in Alaska and had a magnitude of 9.2?
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What caused much of the destruction during the 1964 Alaska earthquake?
What caused much of the destruction during the 1964 Alaska earthquake?
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What magnitude range is attributed to the San Francisco earthquake of 1906?
What magnitude range is attributed to the San Francisco earthquake of 1906?
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The Modified Mercalli Intensity Scale is primarily used to describe what aspect of earthquakes?
The Modified Mercalli Intensity Scale is primarily used to describe what aspect of earthquakes?
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What phenomenon often accompanies major earthquakes like the one in San Francisco in 1906?
What phenomenon often accompanies major earthquakes like the one in San Francisco in 1906?
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What primarily causes most earthquakes?
What primarily causes most earthquakes?
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Which layer of the Earth is the outermost?
Which layer of the Earth is the outermost?
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What is the average thickness of oceanic crust?
What is the average thickness of oceanic crust?
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What characterizes the mantle of the Earth?
What characterizes the mantle of the Earth?
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Which of the following best describes an earthquake?
Which of the following best describes an earthquake?
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How does the Philippine Fault System primarily differ from the United States Fault System?
How does the Philippine Fault System primarily differ from the United States Fault System?
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What is the primary composition of the outer core of the Earth?
What is the primary composition of the outer core of the Earth?
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What occurs when stress builds up along a fault?
What occurs when stress builds up along a fault?
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What design feature helps tall structures survive low frequency vibrations?
What design feature helps tall structures survive low frequency vibrations?
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Which of the following does NOT contribute to the vulnerability of buildings during earthquakes?
Which of the following does NOT contribute to the vulnerability of buildings during earthquakes?
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What is the purpose of the provisions in the National Structural Code of the Philippines regarding earthquake loads?
What is the purpose of the provisions in the National Structural Code of the Philippines regarding earthquake loads?
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How are seismic hazard characteristics for a site determined?
How are seismic hazard characteristics for a site determined?
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Which of the following provinces is included in Zone 2 as per the seismic zoning in the Philippines?
Which of the following provinces is included in Zone 2 as per the seismic zoning in the Philippines?
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What is a recommended method for enhancing the seismic resilience of structures?
What is a recommended method for enhancing the seismic resilience of structures?
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What is a key requirement after a severe earthquake according to the relevant structural code?
What is a key requirement after a severe earthquake according to the relevant structural code?
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What causes tall structures to be particularly vulnerable to vibrations?
What causes tall structures to be particularly vulnerable to vibrations?
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Study Notes
Introduction to Earthquake Engineering
- Earthquakes result from sudden energy release in the Earth's crust, creating seismic waves.
- Stress build-up along fault lines over time often triggers earthquakes.
- Tectonic plate movement is the primary cause of most earthquakes.
Earth Structure
- Earth consists of concentric layers: crust, mantle, outer core, and inner core.
- Continental crust averages 35-40 km (20-25 mi) thick; oceanic crust averages about 7 km (4 mi).
- The mantle extends down to 2,900 km (1,800 mi) and is mostly solid, composed of minerals under high pressure.
Tectonic Plates
- Lithosphere is divided into tectonic plates, leading to seismic activity at boundaries.
- Three types of plate boundaries:
- Divergent: Plates move apart, creating new oceanic lithosphere (e.g., mid-ocean ridges).
- Convergent: Plates collide, leading to one slipping under another, forming mountains or subduction zones.
- Transform: Plates slide horizontally past each other, causing significant earthquakes.
Earthquake Measurement
- Magnitude measures energy release, using the Richter scale (0 to 10+).
- Each whole number increase represents a tenfold increase in seismic wave amplitude.
- The Modified Mercalli Intensity (MMI) Scale measures ground shaking effects, from barely felt (I) to complete destruction (XII).
Major Earthquake Events
- Alaska, 1964: Magnitude 9.2; resulted in 128 deaths and severe infrastructure damage, driven by thrust faults.
- San Francisco, 1906: Magnitude estimated between 7.7 to 7.8; caused extensive destruction and over 3,000 fatalities due to ground shaking and fires.
- Casiguran Earthquake, 1968: Intensity VIII; led to the collapse of the Ruby Tower in Manila, marking one of the most destructive earthquakes in the Philippines.
Seismic Wave Dynamics
- Seismic waves refract differently when passing through materials of varying densities, impacting their speed and direction.
- Lower frequency vibrations can be managed in tall structures with reinforced foundations and design.
Civil Engineering Design Considerations
- National Structural Code of the Philippines (NSCP) aims for seismic-resistant structures to mitigate disaster impacts.
- Inspections and repairs post-earthquake are essential to ensure structural safety.
- The Philippine archipelago is divided into two seismic zones (Zone 2 and Zone 4) based on seismic hazard characteristics and proximity to fault lines.
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Description
This quiz covers fundamental concepts in earthquake engineering, focusing on the causes of earthquakes and the structure of the Earth. Understand the role of tectonic plates, the types of plate boundaries, and the Earth's layering. Test your knowledge on how these elements contribute to seismic activity.
