Tectonic Forces Flashcards
Confining Stress
Uniform pressure applied equally in all directions, causing rocks to compact but not deform significantly
Tension
Stress that pulls rocks apart, often occurring at divergent boundaries, leading to normal faults
Shear
Stress that causes rocks to slide past each other in opposite directions, common at transform boundaries
Elastic Deformation
Temporary strain in rocks that disappears when stress is removed
Plastic Deformation
Permanent bending or warping of rocks without breaking under applied stress
Fracture
Breaks in rock when stress exceeds rock strength, leading to faults or joints
Monocline
A simple bend in the rock layers that does not overturn the structure
Anticline
An upward-arching fold in rock layers
Dome
A circular uplift of rock layers caused by magma intrusion or tectonic forces
Syncline
A downward-arching fold in rock layers
Basin
A bowl-shaped depression in rock layers formed by tectonic forces
Joint
A crack in rock with no relative movement
Slip
The displacement of rock along a fault line
Dip
The angle at which a rock layer or fault slopes from the horizontal
Dip-Slip Faults
Faults where vertical movement occurs along the dip
Reverse Faults
Faults caused by compression, where the hanging wall moves up relative to the footwall
Strike-Slip Fault
A fault where rock move horizontally past each other, common at transform boundaries
Earthquake
Vibrations in the Earth caused by the sudden release of energy along faults
Focus (Hypocenter)
The location within the Earth where an earthquake originates
Epicenter
The point on Earth’s surface directly above the earthquake’s focus
Shallow Earthquakes
Earthquakes that occur at depths less than 70km, often at transform and divergent boundaries
Ring of Fire
A major zone of volcanic and earthquake activity surrounding the Pacific Ocean
Intraplate Earthquakes
Earthquakes occurring within a tectonic plate rather than at plate boundaries
Thrust Faults
A low-angle reverse fault, common in subduction zones
Normal Faulting
Faulting caused by tension, where the hanging wall moves downward relative to the footwall
Crest
The highest point of a seismic wave
Trough
The lowest point of a seismic wave
Amplitude
The height of a wave, indicating energy release
Wavelength
The distance between wave crests
Seismology
The study of earthquakes and seismic waves
Body Waves
Seismic waves that travel through the Earth’s interior
Surface Waves
Seismic waves that travel along Earth’s surface, causing most damage
Seismograph
An instrument that detects and records earthquake waves
Seismogram
A recorded trace of earthquake activity
Seismometer
A device used to measure seismic waves
Mercalli Intensity Scale
Measures earthquake intensity based on observed damage
Shake Maps
Maps showing ground movement and shaking intensity during an earthquake
Richter Magnitude Scale
Measures earthquake magnitude based on seismic wave amplitude
Moment Magnitude Scale
Measures earthquake magnitude based on energy released
Foreshocks
Smaller quakes preceding a larger earthquake
Microfractures
Tiny cracks in rocks that can lead to larger earthquakes
Ground Tilting
Changes in land elevation that may indicate an impending earthquake
Hotspot
An area of volcanic activity caused by a plume of hot mantle material
Magma
Molten rock beneath the Earth’s surface
Lava
Molten rock that reaches Earth’s surface
Eruption
The expulsion of magma, gas, and ash from a volcano
Mama Chambers
Underground reservoirs of molten rock
Viscosity
A measure of a fluid’s resistance to flow; controls eruption style
Large Explosive Eruption
A high-energy volcanic eruption associated with high-viscosity magma
Tephra (Volcanic Ash)
Fragments of volcanic rock and ash ejected during an eruption
Pyroclastic Flow
A fast-moving cloud of hot gases and volcanic material
Lahar
Volcanic Mudflow
Effusive Eruption
A slow lava flow with low explosivity
Pahoehoe
Smooth, ropey lava
Aa
Rough, jagged lava
Vocanologists
Scientists who study volcanoes
Active Volcanoes
Currently erupting or expected to erupt
Dormant Volcanoes
Inactive but could erupt again
Extinct Volcanoes
No longer capable of erupting
Cinder Cones
Small, steep-sided volcanoes formed from explosive eruptions
Supervolcanoes
Massive volcanic systems with the potential for catastrophic eruptions
Caldera
A large depression formed after a major volcanic eruption
Lava Plateau
A flat, extensive lava deposit
Hot Springs
Heated ground water emerging at the surface
Eruption Clouds
Massive volcanic gas and ash plumes
Lava Bombs
Large ejected molten rock fragments
Poisonous Gas
Harmful volcanic emissions like CO2 and SO2
Geothermal Power
Energy harnessed from Earth’s heat
Renewable Resource
A resource that replenishes naturally over time, such as geothermal energy
Population Density
The number of people living per unit area, which influences the impact of natural disasters
