Geography revision Weather, tectonic plates, earthquakes and volcanoes

Where do volcanoes occur mostly and why? Volcanoes occur mostly on or near plate boundaries Volcanoes may erupt if a large richter earthquake occurs. there are also more likely to be faults were the volcanoes are

Location of the pacific ring of fire On or near the plate boundaries

Plate movements Converging - pushing towards each other Diverging- pushing away from each other Transform- rubbing against each other

What is a hotspot? A hotspot is a point where magma rises up from the mantle and forces its way through the crust above. A hotspot is in the middle of a plate

3 types of seismic waves 1. Primary waves - 2. Secondary waves- 3. Surface waves-

Layers of the earth Inner core, outer core, mantle and crust

Weather vs Climate Weather is short term change in the atmosphere at a location Climate is the average weather conditions that are measured over a long period of time

Weather symbols

Effects that an earthquake has on human and natural environments NATURAL- the level of surface may be different The surface waves effect the surface There maybe cracks in the surface HUMAN- no electricity Buildings are destroyed Homes are ruined

Definitions Mantle- the magma layer within the Earth which is between the core and crust Crust- the external shell of molten material, which has hardened. The ocean and continents sit on it Pyroclastic flow- is a avalanche of rock, ash and lava that rushes down the mountain with devastating effects. Lava- magma, or molten rock, that erupts to the Earths surface. Crater- the opening on top of a volcano through which lava erupts Magma chamber- when two plate move apart, molten rock will flow upwards out of the magma chamber Subduction- the process by which, when two tectonic plates collide, one plate slides under another Epicentre- the point on the Earths surface directly above the focus of an earthquake Focus- the point within the earths crust where an earthquake begins Isobar- joins places of same air pressure Hectopascal- the unit of measurement used to show air pressure ( on a isobar) Volcanic bomb- are often solid pieces of lava from post eruptions that formed part of the cone Liquefaction - the process that occurs during an earthquake when soil loses strength due to mixing of ground water and soil particles.

Where do you seismic waves originate? Focus which later moves on to the epicenter