3. Earthquakes Flashcards
What are earthquakes?
Earthquakes are sudden vibrations or shaking of the Earth’s crust caused by movements at plate boundaries and at major fault lines (cracks in the earth’s surface)
Where do the most severe earthquakes occur?
Transform and Convergent boundaries
What are seismic waves?
The energy released by an earthquake is in the form of seismic waves. The waves travel through the crust giving off a series of shocks called tremors
What are foreshocks?
Smaller earthquakes that precede major earthquakes
What are aftershocks?
Smaller earthquakes that follow the main one
What is the focus/ hypocentre of an earthquake?
The origin of the earthquake deep within the crust. From here the seismic waves radiate outwards
What is the epicentre of an earthquake?
The point on the earths surface directly above the focus. Areas closest to the epicentre experience the most damage
What is a fault?
A fault is a break in the rocks that make up the earths crust, along which rocks on both sides have moved past each other. Not every crack in the ground is a fault. What defines a fault is the movement of the rock on both sides
What is a fault scarp?
The fault scarp is the feature on the surface if the earth that looks like a step causes by a slip in the fault
What are Benioff Zones?
Dipping, roughly flat zones of increased earthquake activity produced by the interaction of a sinking oceanic plate with an overriding continental or oceanic plate. Usually associated with deep focus earthquakes
What are seismologists?
Seismologists are scientists who study earthquakes. They use an instrument called an seismograph
What is a seismograph?
A seismograph is an instrument which records the motion of the ground during an earthquake
What is soil liquefaction?
Soil liquefaction is the process in which the cohesiveness of the soil is reduced by seismic waves. E.g Christchurch, New Zealand 2011
What is a tsunami?
A tsunami is a series of waves in a water body caused by the displacement of a large volume of water due to an underwater earthquake. E.g. Japan 2011 tsunami
What is a strainmeter?
A strainmeter measures the build up of stress before an earthquake at a fault line, they can help predict when the rock with break
