Earthquakes Unit 12.2
sudden release of energy Earthquake: shaking of the ground as a result of a ________________________ in Earth’s crust often occurs as a result of _________ between moving tectonic plates that builds-up ____________ about 80% of earthquakes occur in a ring bordering the _______________ the Juan de Fuca convergent plate boundary West of Vancouver Island has many earthquakes friction pressure
sudden release of energy Earthquake: shaking of the ground as a result of a ________________________ in Earth’s crust often occurs as a result of _________ between moving tectonic plates that builds-up ____________ about 80% of earthquakes occur in a ring bordering the _______________ the Juan de Fuca convergent plate boundary West of Vancouver Island has many earthquakes friction pressure Pacific Ocean
Classification of Earthquakes location Focus: _____________ where the pressure is finally released as an earthquake Epicenter: the point on the ____________ ____________ _________ the focus Earthquakes occur at various depths, depending on the plates involved. earthquakes at the surface usually cause _______________ surface directly above more damage Classification of Earthquakes Classification Depth of Focus Shallow Focus 0 to 70 km Intermediate Focus 70 to 300 km Deep Greater than 300 km
vibration source strength Seismic wave: _______________ energy released by earthquakes can tell us the ___________ of an earthquake (where an earthquake happened) can tell us the ____________ of an earthquake source strength
primary wave underground solids liquids gases fastest Longitudinal wave 1st same (P wave)
underground secondary wave solids slower 2nd Transverse wave perpendicular to (S wave)
surface only solids surface wave slowest last (3rd) perpendicular to structural damage (L wave)
composition size faster Seismic waves can tell us the _______________ and _________ of Earth’s interior layers since they behave differently in different materials some can travel underground they travel _________ through solids than liquids faster
The velocity increases Since seismic waves travel faster through solids, this must mean that the outer core is liquid
L S P P mantle
arrival time long magnitude Seismometer: a machine that measures and records seismic wave energy Seismograph: a graph that shows _______________ of seismic waves how __________ an earthquake lasted an earthquake’s ________________ (strength) arrival time long magnitude
5 min 3000 km
The magnitude (size) of an earthquake is the size of the line on the seismograph The magnitude is measured by the Richter Scale an increase of ____ in magnitude = _______ stronger 1 10x 10 102 103