Podcast
Questions and Answers
What type of stress is primarily associated with convergent plate boundaries?
What type of stress is primarily associated with convergent plate boundaries?
Which type of stress causes rocks to lengthen or break apart?
Which type of stress causes rocks to lengthen or break apart?
What is the term for the stress when forces are parallel and moving in opposite directions?
What is the term for the stress when forces are parallel and moving in opposite directions?
Which factor increases pressure on deeply buried rocks?
Which factor increases pressure on deeply buried rocks?
Signup and view all the answers
What happens to rocks during elastic deformation?
What happens to rocks during elastic deformation?
Signup and view all the answers
What magnitude of earthquake is often felt but typically causes minor damage?
What magnitude of earthquake is often felt but typically causes minor damage?
Signup and view all the answers
Which level on the Richter scale corresponds with considerable damage to specially built structures?
Which level on the Richter scale corresponds with considerable damage to specially built structures?
Signup and view all the answers
What is the expected effect of an earthquake with a magnitude of 6.1 to 6.9?
What is the expected effect of an earthquake with a magnitude of 6.1 to 6.9?
Signup and view all the answers
Which geological process is primarily caused by earthquakes and volcano eruptions?
Which geological process is primarily caused by earthquakes and volcano eruptions?
Signup and view all the answers
How frequently do great earthquakes (magnitude 8.0 or greater) occur?
How frequently do great earthquakes (magnitude 8.0 or greater) occur?
Signup and view all the answers
At what magnitude does an earthquake start to typically cause slight damage to buildings and other structures?
At what magnitude does an earthquake start to typically cause slight damage to buildings and other structures?
Signup and view all the answers
What is a primary effect of a magnitude 7 earthquake according to the scale described?
What is a primary effect of a magnitude 7 earthquake according to the scale described?
Signup and view all the answers
Which level on the Richter scale indicates total damage with few, if any, structures remaining standing?
Which level on the Richter scale indicates total damage with few, if any, structures remaining standing?
Signup and view all the answers
What is the key characteristic of a regional tsunami?
What is the key characteristic of a regional tsunami?
Signup and view all the answers
What distinguishes a distant tsunami from other types of tsunamis?
What distinguishes a distant tsunami from other types of tsunamis?
Signup and view all the answers
Which of the following is NOT a primary way earthquakes can lead to fires?
Which of the following is NOT a primary way earthquakes can lead to fires?
Signup and view all the answers
Which measure is essential for reducing the risk of fires caused by earthquakes?
Which measure is essential for reducing the risk of fires caused by earthquakes?
Signup and view all the answers
What mechanism can cause flooding as a result of an earthquake?
What mechanism can cause flooding as a result of an earthquake?
Signup and view all the answers
Which of the following is a recommended practice for managing wildfire risks in earthquake-prone areas?
Which of the following is a recommended practice for managing wildfire risks in earthquake-prone areas?
Signup and view all the answers
Which factor is critical when developing emergency response plans for earthquakes?
Which factor is critical when developing emergency response plans for earthquakes?
Signup and view all the answers
What is NOT a form of earthquake-resistant construction practice?
What is NOT a form of earthquake-resistant construction practice?
Signup and view all the answers
Study Notes
Earthquake Mechanism
- Earthquakes are ground shaking resulting from structures connected to the ground vibrating
- Ground motion, structural vibration, and building destruction are detailed processes in earthquakes (Celebi and Brown, 1994)
Stress and Forces in Earth's Crust
- Enormous lithosphere slabs move unevenly, causing earthquakes
- The Earth's brittle outer layer is under constant stress
- Stress is the force per unit area applied to a rock
- Four stress types act on materials:
- Compression: Rocks are squeezed together; common at convergent plate boundaries
- Tension/Extensional: Rocks are pulled apart; common at divergent plate boundaries
- Shear: Forces are parallel but move in opposite directions; common at transform plate boundaries
- Confining stress: Deeply buried rocks are pushed down by the weight of material above; cannot deform
Rock's Response to Stress
- Elastic Deformation: Rock returns to its original shape after stress is removed; reversible and not permanent
- Plastic Deformation/Ductile Deformation: Rock does not return to its original shape; irreversible and permanent
- Brittle Fracture: Rock breaks
Types of Folds
- Compressive stresses cause rocks to crumple into folds
- Rocks do not return to their original shape after deformation
- Monocline: Simple bend in rock layers; no longer horizontal
- Anticline: Upward-arched fold; oldest rocks at the center
- Syncline: Downward-bending fold; youngest rocks at the center
Types of Earthquakes
- Earthquakes vary in their behavior
- Earthquakes are sudden energy releases in the Earth's crust or upper mantle
- Seismicity is the earthquake frequency, type, and size experienced over time
- Moment magnitude is the most used scale for measuring earthquakes globally, primarily for those above magnitude 5
Seismic Waves
- Seismic waves are vibrations traveling through the Earth's interior or along its surface
-
Body Waves: Travel through the Earth's interior
- Primary (P) waves: Fastest; move through solids, liquids, or gases: Compressional
- Secondary (S) waves: Slower; move only through solids: Transverse
-
Surface Waves: Travel along the Earth's surface
- Love waves: Transverse motion, horizontal; most destructive to structures
- Rayleigh waves: Complex motion; up-and-down, and forward-backward; most felt during earthquakes
Tectonic Earthquakes
- Explained by elastic rebound theory
- Generated when strains in rock masses have accumulated and can't withstand the stresses
- Caused by the sudden fracturing of rock masses
- Example: San Andreas Fault (ruptured in 1906)
Motions of Plate Tectonics During Earthquakes
- Divergent Boundaries: Two plates move away from each other (e.g. Great Rift Valley in Africa, the Red Sea and the Gulf of Aden)
-
Convergent Boundaries: Two plates move towards each other
- Continental-Oceanic: Oceanic plates sink (subduction); create trenches and volcanoes
- Oceanic-Oceanic: One oceanic plate sinks under another, forming volcanoes
- Continental-Continental: Both plates are strong, causing collisions and mountain formation
- Transform Boundaries: Two plates slide past each other (e.g., San Andreas Fault)
Volcanic Earthquakes
- Related to volcanic activity
- Types:
- Volcano-tectonic: Caused by stress changes in solid rock due to magma.
- Long-period: Related to the unsteady transport of magma.
Explosion Earthquakes
- Caused by nuclear or chemical explosions.
Collapse Earthquakes
- Occur due to landslides or material collapsing below the Earth's surface.
- Can result from massive rock movement, steep slopes, heavy rainfall.
Earthquake Magnitude
- Measure of an earthquake's size.
- Proportional to the amount of released seismic energy
- Seismometer data is used to determine the earthquake characteristics (e.g., location, magnitude, time).
- Modern systems precisely amplify and record ground motion over 0.1 to 100 seconds.
Earthquake Intensity
- Measure of shaking and damage caused by an earthquake
- Varies by location
- Many intensity values are distributed around the epicenter
Earthquake Destruction
- Structural damage to buildings
- Injuries and casualties
- Costs
- Psychological effects
- Environmental impacts
Tsunamis
- Caused by earthquakes, landslides, or volcanic eruptions
- Powerful ocean waves generated
- Types: Local, Regional, Distant/Tele
Liquefaction
- Phenomenon where saturated soil temporarily loses strength during earthquakes
- Causes instability, damage to structures, and economic problems
- Happens when excess pore water pressure from cyclic loads weaken the soil.
Fires
- Secondary effect of seismic events; not directly from shaking itself
- Causes: ruptured gas lines, electrical faults, collapsed structures, ignition from friction
- Widespread and difficult to control
Floods
- Earthquakes can indirectly lead to floods through several mechanisms:
- Dam failures
- Landslides
- Debris flows
- Ground rupture effects on rivers
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Related Documents
Description
Explore the mechanisms behind earthquakes and the various stresses acting on the Earth's crust. This quiz covers ground shaking, structural responses, and the types of stress that contribute to seismic activities. Test your knowledge about how the Earth's lithosphere interacts with these forces.
