Plate Tectonics Flashcards
What are Plate Tectonics?
A theory that explains how the Earth’s outer crust moves around over the molten layer below. The crust consists of huge slabs of rocks whose movement can fold mountains and influence the occurrence of earthquakes and volcanoes
Plate Tectonics (continued.)
There are three (3) types of plates.
Convergent plates - when plates collide and one plate rides over the other, forcing it downwards into a subduction zone.
-The denser plate, typically the oceanic plate is subducted by the less dense plate and this can come from mountains, land masses or trenches etc.
Divergent plates - Plates that move away from each other (1). Magma can emerge and form underwater volcanoes (2) The rocks are continually being pushed by the upwelling magma resulting in earthquakes (3).
Transform plates -plates slide past each other and build up in the rocks in each plate and earthquake activity results when the rocks move suddenly to relieve the stress.
The Greater Antilles earthquakes due to the movement of the North American and Caribbean plates (Ex. Haiti 2010)
The Lesser Antilles experience earthquakes due to the movement of the Caribbean and South American plates.
Terms to Know
Seismic Activity - is defined as the vibration of the ground due to the release of elastic energy from the breakage of rock within the earth or an explosion.
Seismic Waves - are energy waves generated by an earthquake or explosion that propagate within the Earth or on its surface.
Seismology - the branch of science concerned with earthquakes and related phenomena.
Richter Scale (a measure of magnitude)
Location and Movement of the Caribbean Plate and its interaction with Other Plates
The Caribbean Plate is a small section of crust that is found under the Caribbean Sea. This slab pushes between the North American Plate and the South American Plate.
It is important to note that as the Caribbean Plate moves eastwards it creates a destructive plate boundary (D.P.B), or volcanic zone in the Lesser Antilles. Another volcanic zone (D.P.B) is found in Central America on the western boundary of the Caribbean Plate with the Cocos and Nazca plates.
Earthquakes, Volcanoes and the Threat of Tsunami
The movement of plates can trigger a number of natural disasters which can have devasting social and economic effects.
Earthquakes- due to movement of the Earth’s crust pressure build-up at the junction where two plates meet. When the rocks cannot take force, they snap into a new position and this vibration is an earthquake. Some earthquakes have a volcanic origin, occur below volcanic vents, and are less destructive.
Volcanoes - an opening in the Earth’s crust which allows ash, lava, steam and hot gases to escape to the surface, creating an atmosphere dangerous to plants and animals around its vent. Over time these eruptions build a cone-shaped mountain.
Tsunamis - a series of high seas waves which may be the result of an undersea earthquake or, more rarely, volcanic eruption that triggers a giant landslide on the sea floor. A tsunami may be three meters or more in height and can flood coastal areas and travel up river valleys, washing people and property away.
Social and Economic Impact of Plate Tectonics on the Caribbean
NEGATIVE OUTCOMES
-Tsunamis destroy coastal areas.
-Earthquakes can cause buildings to collapse through landslides, liquefaction or fires.
-Explosions of hot lava, ash and gases from erupting volcanoes can destroy anything it comes in contact with.
-Poisonous gases emitted from volcanoes prevent plant growth and cause acid rain.
-Flash floods
-Sets back development because of the cost and time needed to rebuild.
-Disruption to the economy due to the closure of businesses and markets.
-Displacement of people through the destruction of homes and other architecture.
POSITIVE OUTCOMES
-Creation of tourist attractions such as Sulphur Springs in St. Lucia
-Access to valuable minerals, including gold, silver and nickel.
-Soils rich in nutrients are useful to agriculture (on volcanic islands)
-Sources of geothermal energy. Ex Monserrat and Nevis are exploring the use of this energy for their hotels.
-Can create coastlines for beaches.
-influences the flow of underground water
-(incidentally) monitoring the inside of Earth and producing seismic hazard assessments for designing earthquake-resistant structures.
Miscellaneous Information
-Authorities, for instance, the UWI Seismic Research Center and Office of Disaster Preparedness and Emergency Management (ODPEM) monitor earthquake activity.
-When these natural disasters occur in the Caribbean, the Caribbean Disaster Emergency Management Agency (CDEMA) deals with these issues to assist in any way possible.
-Advise the public to build structurally integral buildings in order to withstand and reduce damage and casualties during earthquakes and other natural disasters.
-Coordinate plans for disaster relief assistance in areas prone to the most disastrous effects.
-Alert the public via radio and TV broadcasts from local stations to inform them of important information constantly because mobile phone networks may not operate during this.
-Develop educational programmes and awareness campaigns. This can come in the form of evacuation drills to improve a community’s preparedness.
