Geology Reference
In-Depth Information
b.
Explain why there are places where earthquakes occur
but no volcanoes are shown.
and answers ultimately come field observations and
investigations.
Humans impact geology.
Through diverting rivers,
undercutting slopes, drying or wetting soils, extracting
water, or many other activities, humans have the
power to create geologic events where they might not
have otherwise occurred. The deep injection of waste
fluids at the Rocky Mountain Arsenal near Denver
actually triggered earthquakes. Floods in urban areas
may be worse because of the type of development that
has occurred.
c.
On the most useful map for showing plate boundaries,
delineate the boundaries by playing "connect-the-dots".
Show as many plates as you can.
7. Briefly explain Will Durant's statement at the beginning of
the Introduction.
Change is natural and normal.
Rivers meander and
change their courses. People who live near a river
should expect that natural change will continue, and
the river might move from its present location. This
change is predictable but often unwelcome, especially
to landowners near the river. Human activities,
however, can also increase the rate of change. Many
coastal structures have impacts far beyond the site
they are designed to protect.
Geologic events and natural
disasters in the US
No state (and indeed, nowhere in the world) is com-
pletely free from geologic or other natural hazards. In
this section we will look at the types and distributions of
some of the more common hazards that are found in the
United States. We then compare the types of hazards
with their frequency, as measured by Presidential Disas-
ter Declarations. The President may declare disasters for
many reasons, including geological events. A disaster
declaration is made when the large and severe events
occur that have broad impacts, and when these events
are beyond the capabilities of state and local government
to respond. The tremendous damage from wind and
flooding caused by hurricane Katrina is an example of an
event that met all the criteria for a disaster declaration.
Figure II.2 is a map of the United States that iden-
tifies some of the more common hazardous geologic
events in each state.
Population growth places more people at risk.
As population
increases, more people live and work in areas that are
subject to geologic hazards. If hazardous events occur,
more people are impacted. In developed countries, the
impacts are largely monetary; in developing countries,
the impacts are more often measured in loss of lives.
QUESTIONS INTRODUCTION II
GEOLOGIC HAZARDS
1.
Give the definition of a geologic hazard (in your own
words or that provided in the Introduction).
1. a.
What is your home state?
b.
Find your home state on Figure II.2, and list its com-
mon hazardous geologic events.
2.
List 5 geologic hazards.
3. What types of hazards have been omitted from this topic?
2.
Do you think that you personally live in an area of the
state that is subject to these hazards? Why or why not? If so,
which hazards?
4.
Can human activity induce a geologic hazard?
Explain your answer.
3. Identify states that have volcanic hazards. If winds are
blowing from the west to the east, is your area subject to ash
from a major eruption?
5. a.
How many "Key Concepts about Geologic Hazards" are
listed in the Introduction?
b.
List the three that you think are the most important.
4. In 1811 and 1812, a series of major earthquakes in New
Madrid, Missouri (near the southeastern corner of Missouri)
rang church bells along the east coast.
a.
Use a compass and draw on Figure II.2 a circle centered
on southeastern Missouri with a radius that is the dis-
tance from New Madrid to Boston.
6.
a.
From Figure II.1, which geologic process or hazards
map would be the most useful for delineating tectonic plate
boundaries?
