Tectonics 1.3 Flashcards
What type of energy are earthquakes releasing?
Stored;
Where does a pulse of energy radiate out from the earthquakes focus (point of origin)?
out in all directions;
Where is the epicentre located?
Earth’s surface;
What is the epicentre directly above?
Focus;
What can be seen when the earthquake motion displaces the surface?
Fault scarp;
What are the three types of seismic waves generated by earthquakes?
P- Waves
S- Waves
L-Waves
What do P- Waves stand for?
Primary waves;
Are P-Waves fastest or slowest?
Fastest;
What is the approximate speed of P-Waves?
8 km/sec
Do P-Waves cause the most or the least damage?
Least;
What do S and L Waves have that cause more damage?
larger amplitude; energy force
What are P- Waves vibrations caused by?
Compression;
What does S-Waves stand for?
Secondary Waves;
Do S-Waves before or after P-Waves?
After;
What is the speed of S-Waves?
4km/sec;
How do S-Waves cause damage?
Shake ground violently;
What do L- Waves stand for?
Love Waves;
When do L-Waves arrive?
Last;
Where do L-Waves travel only?
On the surface;
Where does vibration occur? (L-Waves)
In the horizontal plane;
L-Waves have a large ‘_______’
Amplitude;
What does having a large amplitude mean for damage?
Significant;
What do L-Waves cause from ground shaking?
Fracturing (ground surface);
What is the severity of earthquakes linked to?
Amplitude; Frequency; Wave Types;
Where can crustal fracturing occur?
Within Earth;
What can earthquakes cause on the ground surface?
Buckle; Fracture;
What is the ruptured fault line of very large earthquakes?
Up to 1000km;
What was the fault line generated by the 2004 Indian Ocean tsunami?
Up to 1000km;
What describes energy pulses being generated along the entire fault length?
‘Unzipping’ a fault;
How long does ground shaking occur for earthquakes that undergo unzipping?
Up to Five Minutes;
What do ‘unzipping’ along fault lines earthquakes have dozens of?
Aftershocks;
What do earthquakes frequently generate as secondary hazards?
Large landslides;
What type of rocks are more likely to experience landslides?
Geologically young;
What can geologically young mountains be referred as?
Unstable;
Name a geologically young mountain range?
Himalaya;
What percentage of deaths did landslides account for in 2008 Sichuan earthquake?
Up to 30%;
What percentage of deaths did landslides account for in 2005 Kashmir earthquake?
Up to 30%;
What type of areas is liquefaction a particular hazard?
ground consists; loose sediment;
Name 3 types of loose sediment.
Sand;
Silt;
Gravel;
What exacerbates liquefaction on ground that consists of loose sediment such as sand, silt or gravel?
Waterlogged;
Where are areas often waterlogged?
Sea; Lakes;
Intense earthquake shaking does what to loose sediment in liquefaction?
Compacts loose sediment together;
What is forced out due to the compaction of loose sediment in liquefaction?
Water;
What direction is water forced out of compacted sediment in liquefaction?
Out; Upwards;
What does forcing water between the sediment out and upwards undermine?
Foundations;
What do undermined foundations cause?
Buildings sink; Tilt; Collapse;
In Japan 2011, what was the degree of tilt that was recorded?
Sixty Degrees;
What is temporary lost in water-saturated material in liquefaction?
Normal Strength;
How does temporarily lost strength of water-saturated ground cause ground to behave?
Like a liquid;
What increases to the point where soil particles can move easily?
Water pressure;
What are the effects of liquefaction?
Infrastructure Damage;
Telecommunications;
How many hazards do major volcanic eruptions frequently have associated with them?
More than one;
What type of plate margin is likely to have more than one hazard associated with them after a volcanic eruption?
Destructive plate margins;
What is it called when there is an indirect consequence of an eruption?
Secondary hazard;
What type of plate margin is associated with secondary hazards after an eruption?
Destructive plate margin;
Name four primary hazards of eruptions.
Lava flow;
Pyroclastic flow;
Ash fall;
Gas eruption;
What is lava flow?
Extensive areas of solidified lava;
How far can lava flow from volcanic vents in lava flow?
Several kilometres;
What factors effect how far lava can flow?
Basaltic;
Low viscosity;
What speed does lava flow occur?
Up to 40 km/hour
Where do lava flows occur?
Subduction zone volcano (composite);
Hot-spot volcano (shield)
What are the dense clouds filled with in pyroclastic flows?
Hot ash;
Gas;
What is the temperature of pyroclastic flows?
Up to 600’C
Where can pyroclastic flows flow down?
The flank of volcanoes;
Where do pyroclastic flows occur?
Subduction zone volcano (composite)
What can ash particles and larger tephra particles do to areas?
Blanket them;
What are the effects of ash fall?
Killing vegetation;
Collapsing buildings;
Poisoning water sources;
What does ash fall do to vegetation?
Kill;
What does ash fall do to buildings?
Collapse them;
What does ash fall do to water sources?
Poisons them;
Where does ash fall occur?
Constructive plate margin volcanoes (cinder cone, fissure eruption)
Subduction zone volcano (composite)
What are the two main gases from gas eruption?
Carbon dioxide; Sulphur dioxide
What can gas eruptions do to people and animals in extreme cases?
Poison them; Suffocate them;
Where does gas eruption occur?
Subduction zone volcanoes (composite)
Hot-spot volcano (shield)
What are the secondary hazards of volcanic eruptions?
Lahars;
Jökulhlaups;
What are lahars?
Volcanic mudflows;
When do lahars occur?
When rainfall mobilises volcanic ash:
Where do lahars flow down at high speed, which causes major disruption?
River systems;
Where do lahars occur?
Subduction zone volcanoes (composite);
What are Jökulhlaups?
Devastating floods;
When do Jökulhlaups occur?
Volcanoes erupt beneath glaciers/ice caps;
What do Jökulhlaups create huge volumes of?
Meltwater;
Where are Jökulhlaups common?
Iceland;
Where do Jökulhlaups occur at?
Constructive plate margin volcanoes (cinder cone, fissure eruption)
What type of volcano in most cases represents a significant hazard?
Large composite volcanoes;
What type of plate boundary do large composite volcanoes, in most cases, represent a significant hazard?
Convergent plate margin (destructive)
What do large composite volcanoes found at destructive plate margins have that represents a significant danger?
Lava flows; Pyroclastic flows; lahars; Extensive ash; Tephra fall
How far do eruptions that have lava flows, pyroclastic flows, lahars and extensive ash and tephra fall effect?
Up to 30km from the volcanic vent;
What type of volcano is a subduction zone volcano?
Composite;
What type of volcano is a hot-spot volcano?
Shield;
What type of volcano is a constructive plate margin volcano?
Cinder cone; Fissure eruption;
