Earthquakes and Volcanoes Vocabulary Unit 2 Earths Systems
Earthquakes and Volcanoes Vocabulary Unit 2: Earth’s Systems and Resources
Earthquake Seismic vibrations produced when rocks break along a fault
Fault Surface that rocks move along when they pass their elastic limit and break
Normal Fault Break in rock caused by tension forces, where rock above the fault surface moves down
Reverse Fault Break in rock caused by compressive forces, where rock above the fault surface moves upward
Strike-slip Fault Break in rock caused by shear forces, where rocks move past each other without much vertical movement
Tension Forces Cause rocks to be pulled apart
Compression Forces Squeeze rocks together
Shearing Forces Push rocks past each other
Focus In an earthquake, the point below Earth’s surface where energy is released in the form of seismic waves; sometimes referred to as the hypocenter
Epicenter Point on Earth’s surface directly above an earthquake’s focus Watch
Primary Waves Moves rock particles back and forth in the same direction that the wave travels; fastest type of seismic wave
Secondary Waves Moves rock particles at right angles to the direction of the wave Watch
Surface Waves Moves rock particles up and down in a backward rolling motion and side to side in a swaying motion; slowest type of seismic wave and causes the most damage
Seismograph Instrument used to register earthquake waves and record the time that each arrived Watch
Seismogram The paper record created by the seismograph
Magnitude Measure of the energy released during an earthquake Philippines earthquake in July 2017
Richter Magnitude Scale Describes the strength of an earthquake based on the height of the lines on the seismogram
Mercalli Intensity Scale Describes the intensity of an earthquake using the amount of structural and geologic damage in a location
Shadow Zone A small area of Earth that does not receive seismic waves from an earthquake
Liquefaction Occurs when wet soil acts more like a liquid during an earthquake Watch
Ring of Fire Region of high volcanic and seismic activity surrounding the majority of the Pacific Ocean – made up of converging plate boundaries Watch
Hotspot An area in the mantle from which heat rises in the form of a thermal plume from deep within the Earth Watch
Hawaiian Island Chain Volcanic islands that form as a result of plate tectonic movement over a hotspot
Volcanic Island Arc A curved chain of volcanic islands that form at convergent plate boundaries where subducting oceanic crust is melted, allowing magma to rise through the crust to form volcanoes Ex. Aleutians, Japan, New Zealand, Philippines, Caribbean Watch
Acid rain Rainfall containing elevated levels of strong acids resulting from rainfalling through volcanic emissions
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