Short Term On the morning of the 13th July 2001, magma pushed up through one of Etna’s vents. This caused the south side of the volcano to bulge and caused a series of earthquakes. Lava bubbled up to the surface in the crater of the volcano, and also at several...
This submerged mountain range, which extends from the Arctic Ocean to beyond the southern tip of Africa, is but one segment of the global mid-ocean ridge system that encircles the Earth. The rate of spreading along the Mid-Atlantic Ridge averages about 2.5 centimetres...
Primary and Secondary Effects Lahars killed 70% of Armero’s population 45km away. Lahars were as much as 40m thick and travelled at 50km per hour. Most killed by suffocation as lahars up to 8m buried them. Lahars killed 1,800 people in Chinchina. 3400 ha of...
A theoretical model of the formation of magnetic striping. New oceanic crust forming continuously at the crest of the mid-ocean ridge cools and becomes increasingly older as it moves away from the ridge crest with seafloor spreading. Early in the 20th century,...
316,000 people were killed, and 1 million people were made homeless. 300,000 people injured. 3 million people were affected by the earthquake. 250,000 homes and 30,000 other buildings, including the president’s palace and 60% of government buildings were either...
Oceanic crust is denser than continental crust, when plates collide the oceanic crust is subducted into the upper mantle, asthenosphere. Subduction creates several features characteristic of destructive margins. As the ocean crust descends, friction with the overlying...
Effects Buildings collapsed they were built on a blind thrust fault, so land buckled. 57 people died. Infrastructure ruined, extensive damage to parking structures/freeway overpasses. Most damage occurred in multi-story frame blocks. Numerous fires due to broken gas...
Where two pieces of oceanic crust on different plates collide, one is subducted beneath the other. The crust that is subducted may be marginally denser of the two plates or is the one which is moving more quickly. These form characteristically curving lines of new...
A tsunami is a giant sea wave caused by the large-scale displacement of water. Tsunamis are triggered by four events: Earthquake, landslide, volcanic eruptions (Krakatau 1883) and meteorites. In all four cases the tsunami is triggered by the displacement of...
Two continental crusts collide and as neither can sink, they are forced up into Fold Mountains. The Indian plate collided with the Eurasian plate forming the Himalayas. The Himalayas are constantly changing, because these highly folded and faulted regions do not...
Oceanic ridges form the longest continuous uplifted feature on the surface of the Earth, having a total combined length of over 60,000km. Where two plates pull apart there is a weaker zone in the crust and increase in heat near the surface. The hotter, expanded crust...
Conservative margins occur when two plates move parallel or nearly parallel to each other these margins are said to be conservative because neither plate is subducted nor there is no volcanic activity. The constant stick slip motion of the plates results in frequent...
The ocean trenches are narrow depressions in the sea. These trenches form the deepest points in the ocean and are the lowest points on earth. Ocean Trenches are formed at a place of plate boundary which is known as the subduction zone. It experiences frequent...
Convection currents in the asthenosphere cause continental crust to dome upwards. The upward pressure causes the crust to crack leaving an unsupported middle section. The unsupported section collapses forming a rift valley with steep stacks. If the convection currents...
The middle of the Pacific Ocean is the volcanic Hawaiian Islands that aren’t connected with any plate boundary normally associated with plate margins. The volcanoes are caused by a localised hotspot within the Pacific Plate. The concentrations of radioactive elements...
Volcano, an extrusive feature formed from the accumulation of erupting lava and/or volcanic ash. Volcanoes are found at both constructive and destructive margins and the distribution follows the pattern of the plate boundaries. Volcanoes at destructive margins erupt...
Geysers A geyser is a rare kind of hot spring that is under pressure and when it erupts it sends jets of water and steam into the air. They are a tube-like hole in the ground that runs deep into the crust in which they are filled with water. Water in the lower part of...
Batholith:A Batholith is when magma forces its way into the crust but becomes trapped and solidifies into rock, it is a large mass of intrusive igneous rock believed to have solidified deep within the earth. When it cools it forms granite and this can be exposed due...
Primary Effects Lava flows – although lava is the greatest perceived threat it rarely moves fast enough to kill people before they are evacuated. However, lava flows that cannot be diverted can cause damage. Pyroclastic flow – during and after the initial eruption gas...
Social Around 10 million airline passengers affected and stranded abroad Residents in the volcano shadow were covered in ash and may have evacuated Sports games across the globe had to be cancelled or postponed 20 farms were destroyed by the flooding or ash The 150m...
Geomorphology– the study of landforms of the earth’s surface Plate tectonics– a theory explaining the structure of the earth’s crust and many associated phenomena as resulting from the interaction of the rigid lithosphere. Geomorphological hazard– an event causing...