Cyclones
True or False: Cyclones are a huge moving high-pressure weather systems that form in tropical areas.
FALSE. Cyclones are a huge moving low-pressure weather systems that form in tropical areas.
True or False: During the 1902 eruption of Mt Pelee, 200 people died of snake bites, when the snakes invaded the city following tremors from the volcano.
False! 50 people and 200 animals died of snake bites.
True or False: There are three types of seismic shock waves: P, S and L waves.
False! There are 4. P, S, L and R.
In December 2004, a massive magnitude 9.2 earthquake struck where?
On the sea floor off Sumatra, Indonesia.
Describe one impact of cyclones on the lithosphere.
Examples: Erosion of coastlines, soil erosion, sediment carried to rivers and other bodies of water.
Effect on the atmosphere: Name TWO gases that volcanoes emit during an eruption.
Any of the following: carbon dioxide, sulfur dioxide, carbon monoxide, water vapour.
Earthquakes can cause landslides. How do landslides affect the biosphere?
Examples: Bury villages and forests, deaths by damages from falling buildings, roads, and bridges.
What is the top speed of some spiraling winds in a cyclone?
Up to 300 km per hour.
Describe one impact of cyclones on the hydrosphere.
Examples: Seas rise, storm waves in low-lying coastal areas, large scale floods, rising of water table.
Volcanoes emit aerosols from their vents during an eruption. What is the effect of this on climate?
Global cooling can occur. Sulfate aerosols absorb the Sun's radiation.
Explain the effect of a deep-focus earthquake under the ocean floor.
Earthquakes at sea can generate tsunamis. The massive waves inundate low-lying coastal areas, destroying build up areas and can cause loss of life.
How fast are pyroclastic flows from a volcanic eruption?
A pyroclastic flow is a fast-moving current of hot gas and volcanic matter that rushes down the slopes of a volcano. They typically move at speeds of over 100 kilometers/hour and reach temperatures of over 400 degrees Celsius.
Describe one impact of cyclones on the biosphere.
Examples: Destruction of plants and crops, killing animals, re-distribution of animals, seed dispersal.
Explain one positive effect of volcanic eruptions.
Volcanic ash and rock can replenish the nutrients in soil, making them more fertile. This would increase agricultural yield.
Describe TWO impacts of earthquakes on the lithosphere.
Examples: Soil liquefaction, breaking of rocks under roads and pipes, fissures created in the ground.
Which type of seismic wave is the slowest, but most destructive?
R (Rayleigh) waves.
How do cyclones form?
Wherever air pressure is low, water evaporates forming clouds and rain. Surrounding air rushes in to equalise the pressure, producing strong surface winds to spiral upwards.
Describe TWO impacts of volcanic eruptions on living things.
Examples: Ash fallout smothers plants, death of plants and animals caused by lahars, pyroclastic flows, lava flows, ash buildup on homes crushes people inside, etc.
Compare the Mercalli and Richter scales. Give two differences.
Mercalli - intensity based on observed effects, using a linar scale. Richter - based on energy in seismic waves, using a logarithmic scale (10-fold increase in size).
Explain the great loss of life during the 1985 Nevado del Ruiz volcanic eruption in Columbia.
Minor earthquakes and steam emitted from the volcano before ash and pumice fragments were expelled from the volcano. An evacuation was declared and cancelled as the eruption seemed to subside. Shortly afterwards, pyroclastic flows and lahars moved towards the town but were hidden by a storm. 23,000 people and 15,000 animals perished.