Tectonics 1.1 Flashcards
What are tectonic hazards?
Threats caused by movement of tectonic plates
Where do earthquakes occur?
Edges of tectonic Plates
Intraplate regions
Earthquakes found in intraplate regions may be built up by what?
Stress (built up)
In Intraplate regions, earthquakes may be related to stress built up by?
Continental Rifting;
Stress transfer (from other regions)
Most active volcanoes occur near to?
Plate boundaries;
What percentage of volcanoes occur around the ‘Ring of Fire’?
About 75%;
Where is the ‘Ring of Fire’ located?
Pacific Ocean;
What type of plate boundaries do volcanoes occur at?
Convergent; Divergent
Volcanoes can be found at hotspots in the middle of plates.
Name an example.
Hawaii; Central Pacific
What percentage of tsunamis occur around the Pacific Ocean?
Over 70%
What percentage of Tsunamis occur around the Mediterranean Sea?
15%
How many Tsunamis occur around the Caribbean Sea and Atlantic Ocean?
9%
How many Tsunamis occur around the Indian Ocean?
6%
What are tsunamis caused by?
Tectonic Activity
Which type of plate boundary causes the most tsunamis to occur due to their activity?
Convergent boundaries;
Three main types of plate boundary?
Convergent;
Divergent;
Conservative;
What are the three main earthquake belts?
Pacific;
Mid- Atlantic;
Alphide;
Some earthquakes occur away from active plate boundaries- for example old plate boundaries or faults - where weaknesses are; How often are these, relativity?
Rare and low intensity;
How many active volcanoes are in the world?
500
How many volcanoes erupt each year?
50;
There is little scientific data around what type of volcanoes?
Submarine;
The most explosive volcanoes are produced from what type of plate boundary?
Convergent;
What dissolved gases do convergent volcanoes’ magma have high levels of?
Silicon; Oxygen
What do silica rich plates produce?
Silica rich magmas;
Where do silica rich magmas come from?
Melted continental crusts;
What do earthquakes at divergent boundaries tend to be?
Shallow; Low Magnitude;
What do volcanic eruptions tend to be at divergent boundaries?
Small; Effusive
What does effusive mean?
Basaltic magma; Becomes lava; Solidifies
What type of lava are usually of volcanic eruptions at divergent boundaries?
Basaltic lava;
Is there high or low gas content at divergent volcanic eruptions?
Low gas content
Does basaltic lava have high or low viscosity?
High Viscosity;
Is basaltic lava high or low temperature?
Higher temperature;
What zone do friction and pressure build up at convergent boundaries to cause strong earthquakes?
Benioff Zone
What do volcanic eruptions tend to be at convergent boundaries?
Volatile
Why do volcanic eruptions at convergent boundaries tend to be more volatile?
Magma;Forcing; Surface; Pressure
Do volcanic eruptions at convergent boundaries have high or low gas content?
High gas content;
Do volcanic eruptions at convergent boundaries have high or low viscosity?
Low viscosity;
Are volcanic eruptions at convergent boundaries higher or lower temperature?
Lower temperature;
What type of lava do volcanic eruptions at convergent boundaries tend to have?
Rhyolite lava;
What do plates do at conservative boundaries to cause a significant amount of pressure?
Stick;
What does the sticking of plates at conservative boundaries create?
Pressure; Powerful Earthquakes;
Intra-plate volcanism is also known as what?
Hotspot volcanism;
Where do Hotspots occur?
Away from plate boundaries;
What is the name of the stationary columns of rising magma in the asthenosphere, where hotspots occur?
Mantle Plumes
What are stationery mantle plumes?
Columns of rising magma;
Where do hotspots occur over?
Stationary magma plumes;
What moves over the stationary mantle plume?
Tectonic plate;
What does the tectonic plate moving over the stationary mantle plumes cause?
Island Arcs (Hawaii)
Which is the oldest island in island arcs formed at hotspots?
Island furthest away from the plume;
What type of boundary is Iceland at?
Divergent;
How wide is the mantle plume Iceland is located on?
30-50km
In Iceland’s 2010 eruption, what grounded planes over a large portion of the Northern Hemisphere?
Volcanic dust;
