Earthquakes - ~95% of all earthquakes along plate boundaries 80% of the world’s earthquakes occur in a ring that borders the pacific ocean - Ring of Fire An Earthquake starts at a location inside the Earth called a (foci) “focus” The is the point on the EARTH’s SURFACE directly above the focus. “epicentre” are the vibrations (waves) of energy released by a quake! SEISMIC WAVES - Primary-wave: - Fastest to side motion -Side (These make the sound that we hear) Secondary-wave: -S for “secondary” -Up/down motion Surface waves: -Slowest -Travel only on ground (or water) surface -Damaging to structures -Circle Motion The is for measuring the strength Richter's magnitude scale ("size") of earthquakes Volcanoes Composite Volcano Mt. St. Helens (cone-shaped) – Found along plate boundaries, usually by subduction zones Layers of ash and thick lava form a tall cone. As magma reaches the surface, it cools, hardens, and traps gases below. Pressure builds; eventually, there is an eruption. 2) Shield Volcano (Hawaii Island,Yellowstone, largest type) - these are not found at plate boundaries but instead form over hot spots. - Thin magma/lava flows out from a hot spot and forms a low, wide cone. 3) Rift eruptions - occur at rifts and ridges (diverging plate, cracks in lithosphere) - fountains of lava, Not very destructive or violent
Earthquakes - ~95% of all earthquakes along plate boundaries 80% of the world’s earthquakes occur in a ring that borders the pacific ocean - Ring of Fire An Earthquake starts at a location inside the Earth called a “focus” (foci) The “epicentre” is the point on the EARTH’s SURFACE directly above the focus. SEISMIC WAVES - are the vibrations (waves) of energy released by a quake! Primary-wave: - Fastest -Side to side motion (These make the sound that we hear) Secondary-wave: -S for “secondary” -Up/down motion Surface waves: -Slowest -Travel only on ground (or water) surface -Damaging to structures -Circle Motion The Richter's magnitude scale is for measuring the strength ("size") of earthquakes Volcanoes Composite Volcano – Mt. St. Helens (cone-shaped) Found along plate boundaries, usually by subduction zones Layers of ash and thick lava form a tall cone. As magma reaches the surface, it cools, hardens, and traps gases below. Pressure builds; eventually, there is an eruption. 2) Shield Volcano (Hawaii Island,Yellowstone, largest type) - these are not found at plate boundaries but instead form over hot spots. - Thin magma/lava flows out from a hot spot and forms a low, wide cone. 3) Rift eruptions - occur at rifts and ridges (diverging plate, cracks in lithosphere) - fountains of lava, Not very destructive or violent