Past Questions Flashcards
Distinguish between a hazard and a disaster
Hazard
A dangerous situation that poses danger to human life
Has less critical consequences
Take its full shape after a series of events, which might have led it to happen
Disaster
An event that completely causes damage to human life and property/environment
Has more critical consequences and more catastrophic
Often happens suddenly/unexpectedly, causing more severe effects
Plate boundary/ volcano/ eruption summary
Divergent
Effusive
Mafic (Basalt/Gabbro)
Weak
Convergent (Subduction Zone)
Explosive
Semi-mafic (Andesite/Diorite)
Deep/Strong
Convergent (Continental-continental)
None
N/A
Surface/Strong
Transform
None
N/A
Surface/Strong
Intraplate
Hot Spot
Various
Occasional and weak
Landslides and Tsunamis
Landslides - a landslide is any geologic process in which gravity causes rock, soil, artificial fill or a combination of the three to move down a slope.
Caused by disturbances in the natural stability of a slope. They can accompany heavy rains or follow droughts, earthquakes, or volcanic eruptions.
The movement that occurs during an earthquake can cause the surface material to slide down a slope.
Tsunamis are large, potentially deadly and destructive sea waves, most of which are formed as a result of submarine earthquakes. They can also result from the eruption or collapse of island or coastal volcanoes from giant landslides on marine margins.
Account for the difference in the depth at which earthquakes originate at divergent and convergent boundaries.
Convergent boundaries typically produce deep focus earthquakes as the oceanic crust penetrates deep into the mantle. A divergent boundary found at a mid-ocean ridge is where the oceanic crust is relatively close to the surface and it will produce shallow focus earthquakes.
Explain how both tsunamis and lahars are produced
Tsunamis are waves of various sizes that result from an oceanic volcanic eruption, earthquake or landslide that causes the displacement of water. As earthquakes occur, water is displaced and the tsunami wave is formed.
Lahars are a type of flooding unique to volcanic eruptions. Fast flowing water mixes with ash and loose rubble. The water may come from melted snow and ice, displaced lakes or heavy rain during eruption. The mixture moves down slopes because of gravity.
Identify 2 hazards associated with earthquakes and explain the effect that each has on the environment
Earthquakes generate a series of seismic waves which pass through the crust causing the ground to shake. This causes cracks in built structures and weakens foundations, which can lead to the collapse of structures such as buildings and dams.
Tsunamis are generated by a shift in crustal slabs which moves the ocean above and causes massive waves which wipe out structures and ecosystems. This causes death and destruction as the surge carries large amounts of energy and debris.
2020 29a) Account for the trends in the data
The apparent increase in all eruptions over the time period specified may have been due to improvements in technology which has allowed us to identify and report on volcanic eruptions, especially those that occur some distance from established human populations which previously would have gone unreported.
The major volcanic eruptions data has remained relatively constant because the events are sufficiently noticeable for all to have been reported and recorded over the past two centuries.
2 modifications to the graph that would aid in its interpretation
- Include a key to identify the various events indicated under ‘all eruptions’
- Include a label for the secondary vertical axis
Earthquake depth at subduction zones
ocean/ocean divergent plate boundary –> uniformity on either side, shallow near the ocean trench and deeper earthquakes detected inland from the trench
ocean/continent convergent plate boundary –> earthquakes on either side of the margin, typical of a subduction zone. Earthquakes deep within the mantle as the ocean plate subducts
2021 29a and b
