Natural Events and the Environment Practice
Coastal urbanization does not increase the risk to human communities from which of the following natural disasters? a. earthquakes b. floods c. hurricanes d. cyclones
A. Earthquakes
Which of the following is true concerning hurricanes? a. They tend to deposit more sediment than they remove. b. Their storm surges cause widespread flooding. c. They have fast, but generally weak wind gusts. d. They do not alter landscapes significantly.
B. Their storm surges cause widespread floooding
Tsunamis are the result of _______. a. undersea volcanic eruptions b. undersea earthquakes c. hurricanes d. all of the above
B. Undersea earthquakes
Breaks in which of the following led to the flooding of New Orleans during Hurricane Katrina? a. sea walls b. groins c. levees d. barrier roads
C. Levees
Explain how the disposal of human waste could worsen the effects of hurricanes on coastal communities.
Coral reefs act as wave breaks and reduce the effects of storm surges from hurricanes by helping to absorb the impact of waves. When coral reefs die they are no longer as effective as wave breaks which worsens the impacts of storms for coastal communities. The disposal of human waste along coastlines and off of coasts can contribute to coral contamination and can lead to coral death, indirectly worsening the impact of hurricanes on coastal communities.
The mixture of water and rubble that flows from the slope of a volcano is a _______. a. pyroclastic flow b. fumaroles c. tephra d. lahar
D. Lahar
Explain how deforestation can permanently increase an area's risk of flooding.
Deforestation is both the removal of trees and the permanent retasking of the land for non-forestry purposes. Therefore, since tree roots help aerate soil and improve soil water retention, this permanent removal of trees reduces the amount of water that soil can absorb and increases the amount that will perforce flow over the ground as runoff. Increased surface runoff leads to flooding.
What distinguishes surface and body seismic waves?
Seismic waves that move below the surface of the Earth are body waves and are the first to occur. Body waves are composed of two different types of waves, P and S waves. S waves occur after P, and are the most damaging seismic waves. Seismic waves moving along the surface of the Earth are surface waves and are the last type of seismic wave to occur.
Distinguish between the different ways volcanoes cause damage.
The volcanic plume of an eruption is the pyroclastic flow which sends large amounts of ash and rock into the air and along the ground surrounding the volcano. When this ash and rock mixes with water it forms lahars which flows down the slopes of volcanoes like a landslide, clearing everything in its path. The rocks thrown into the air by the pyroclastic flow, tephra, fall to the ground causing damage where they strike. Toxic gases released through fumaroles can result in acid rain, air pollution and can deplete atmospheric ozone. And of course molten rock emitted from volcanoes as lava flows in streams down volcanoes destroying vegetation and property wherever it touches.
Explain how human activities can intensify, or even cause a landslide.
Trees and other vegetation anchor soil in place and prevent rain and floodwaters from eroding too much of it. When humans clear this vegetation away, for the timber or development, this leaves the exposed ground in greater danger of landslides.
