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Questions and Answers
What is primarily responsible for the majority of earthquakes?
What type of earthquakes are caused by the buildup of stresses within rocks?
Which of the following is considered a natural but rare case of transient ground disturbances?
Which process is indicative of volcanic tremors?
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What is one of the main components necessary to understand earthquakes?
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The reactivation of which geological features typically leads to earthquakes?
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Which phenomenon is NOT primarily associated with tectonic earthquakes?
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What type of seismic waves are typically felt during an earthquake?
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What was the original magnitude assigned to the 1906 San Francisco earthquake?
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What was the estimated length of the rupture caused by the 1906 earthquake?
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How long did the fire caused by the earthquake burn uncontrollably?
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What was the maximum displacement recorded near Shelter Cove during the earthquake?
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Who developed the elastic rebound theory following the San Francisco earthquake?
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What primary factor contributed to the inability to contain the fire post-earthquake?
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In comparison, what was the length of the rupture during the 1989 Loma Prieta earthquake?
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What was one of the significant outcomes of the investigations after the San Francisco earthquake?
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What is necessary to estimate the magnitude of an earthquake using a seismogram?
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Which of the following statements about the Richter scale is true?
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In the equation $M = ext{log}_{10}(A/KT) + riangle + S$, what does the variable 'M' represent?
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What is the Modified Mercalli intensity scale primarily used for?
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According to the content, how does the total energy released by multiple earthquakes of magnitude M compare to that of a single earthquake of magnitude M + 1?
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Which magnitude measurement primarily uses P-waves?
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What does intensity refer to in the context of earthquakes?
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What is the highest intensity class on the Modified Mercalli scale?
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What does the first volume of the discussed study focus on?
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Which position is currently held by Harsh Gupta?
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How many books has Harsh Gupta authored?
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Which committee did Harsh Gupta chair?
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Which association was Harsh Gupta the Vice-President of?
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What specific area of earthquake research is highlighted in Harsh Gupta's work?
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What is a notable professional society that Harsh Gupta founded?
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Where is Harsh Gupta an Adjunct Professor?
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Which intensity level on the Modified Mercalli scale corresponds to vibrations similar to passing light trucks?
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At which intensity level are liquids disturbed and small unstable objects displaced?
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What occurrence is noted at intensity level VII?
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Which statement about intensity level VI is false?
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What is a characteristic of intensity level IV on the Modified Mercalli scale?
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At which intensity level might people not recognize that an earthquake has occurred?
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Which of the following is true regarding intensity level VIII?
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How do the effects on hanging objects change from intensity level V to intensity level VI?
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Study Notes
Basics of Seismology
- Earthquakes are caused by the buildup of stress in rocks that exceeds their strength, resulting in fractures.
- Seismic waves radiate from the point of fracture, causing ground shaking.
- Tectonic earthquakes are predominantly associated with faults, often reactivating pre-existing faults.
- Volcanic regions can experience transient ground disturbances due to gas release and magma movement.
- Other rare natural disturbances include landslides, cave collapses, and meteorite impacts, alongside human-made disturbances from explosions and mining.
Earth's Structure
- Earth's radius is approximately 6,371 km, structured in concentric spherical shells.
- Seismometers record seismic wave amplitudes; magnitude is estimated by correlating wave motion with the distance from the earthquake.
- A variety of magnitude scales have developed beyond the original Richter scale, with body wave magnitudes (mb) and surface wave magnitudes (Ms) being commonly used.
- Energy released in earthquakes scales exponentially; a single M+1 earthquake releases energy equivalent to 32 M earthquakes.
Earthquake Intensity
- Intensity measures the damage caused by an earthquake, categorized using the Modified Mercalli (MM) intensity scale.
- The MM scale ranges from I (not felt) to XII (total destruction), with subjective assessments by observers.
- Documented intensity effects include vibrations, displacement of objects, structural damage, and panic among individuals.
Historical Earthquake Events
- The 1906 San Francisco earthquake, originally rated at magnitude 8.3, later revised to 7.8, featured a rupture length of approximately 470 km.
- The event caused massive destruction, fires, and significant economic losses, influenced by structural vulnerabilities like ruptured water pipelines.
- Elastic rebound theory, formulated by Dr. Henry Fielding Reid, explains seismic activity and is foundational to earthquake models.
Biographical Sketch of Harsh Gupta
- Harsh Gupta is a prominent seismologist noted for his research on reservoir triggered earthquakes.
- He has authored three books and over 130 academic papers in international journals.
- Positions held include Secretary in the Government of India’s Department of Ocean Development and Director of the National Geophysical Research Institute in India.
- Gupta is a founding member of several seismic and geological organizations, contributing significantly to global earthquake research and assessment initiatives.
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Description
Test your knowledge on the fundamentals of seismology, including the definition of earthquakes, causes, and the propagation of seismic waves. This quiz covers the essential concepts and aims to provide a clear understanding of how earthquakes occur and their implications.
