Assignments
A 'Virtual Earthquake' exercise for ALL students
- Visit http://www.sciencecourseware.org
- Click on Geology Labs, then select the epicenter and magnitude button.
You can also try out the other functions if you wish.
EARTHQUAKE HAZARDS
The assignment includes two exercises, which should be completed
according to the schedule provided to you.
Exercise 1 This
exercise describes felt effects of an earthquake that you are required
to interpret and use to construct an isoseismal map.
A farmer
some 130 km east of Centre City did not notice any evidence of an
earthquake. His grand-daughter, a first year student at Muddy Polytechnic,
was getting ready to go to a dance and panicked and ran out of the
hostel when plaster began to crack and fall off the walls of her
room. Her partner for the dance, a rather imperceptive chap, was
driving south from Centre City on Highway 5 about 15 km north of
the Polytechnic. He did not notice the cracks in the ground on the
west bank the Muddy River, although the road had seemed a little
rough earlier in the journey. He had not even noticed the fallen
chimneys in Southville as he drove through. People 80 km south of
the Polytechnic had not noticed the earthquake either and neither
had the people who lived on the Red and Black Hills.
A Housewife in Centre City first noticed the dishes rattling on
the Dutch dresser and her cousin, who lived 10 km south of town,
claimed that his grandfather clock had stopped. The schoolteacher
from Eastville reported that pictures on the walls in the dining
room of his house had swung to and fro. The mother of one of his
pupils, who lived 25 km to the East, had noticed the quake as she
sat at her sewing desk but her husband out in the field feeding
out hay had not.
At Leakey Dam the power utility caretaker noticed water slopping
down the spillway of the dam but did not feel any shaking, although
it was felt distinctly by a fisherman at the north end of the lake.
A family in a farm house about 2 km north of the lake heard creaking
and noticed that some objects were swinging. Nobody south of the
Dam noticed anything.
In Northville an elderly man was woken up from his late afternoon
snooze and his health care assistant thought it was a truck passing
by on the highway. A neighbour noticed the shaking, probably because
he was lying on his back under his car. The Security person at the
hardware store 10 km west of Centre City said she thought that the
tinware was going to fall off the shelves as it rattled so much.
They were having such a good time at the dance in the country hall
10 km west of West School that not a soul noticed the earthquake,
except some parents waiting in their car to pick up their children.
They did not realise it was an earthquake at the time.
Although many people in Centre City felt the earthquake, no one
was frightened and no damage was reported. Several people estimated
that the shaking lasted for over one minute. The most annoyed person
in the area was an amateur seismologist at Northville. In all his
excitement on feeling the quake (he was one of the few to do so
in Northville) he put his seismogram into the fixer instead of the
developer and lost the trace. Now he does not know any details about
the size of the earthquake. During the following month he visited
all the towns in the valley and gathered information on the intensity
of the shock using the Modified Mercalli scale. Since he heard you
were doing a course in seismic hazards he wants to give you his
data for you to draw up isoseismal lines (on the base map supplied),
estimate the probable location of the epicentre and determine the
approximate Richter magnitude. Assume that the earthquake is shallow
and use equation 1.
N.B.
On the table of Mercalli scale categories, ADD to
category V the following: Pendulum
clocks may stop.
Exercise 2 By using the published material available for the Edgecumbe earthquake
(see references) write a report of no more than 10 pages on the
seismic hazard in the Bay of Plenty. In your report you should address
the following topics:
Location
Cause
Magnitude and Intensity
Impact
Risk Factors
Prediction of frequency and size of future seismic events.
Use any maps or illustrations you feel are necessary.
If you wish you may select another earthquake for which you have
found sufficient information and report on seismic hazard in the
region in which the earthquake occurs in terms of the factors listed
above.
References Cited
Aitken, J J and Lowry M A 1995. More Earthquakes Explained. Institute
of Geological and Nuclear Sciences information series 35.
Ambrose J and Vergun D, 1990. Simplified building design for wind
and earthquake forces. Earthquake effects on buildings, Wiley,
New York, 2nd edition.
Bryant
E. 1991. Natural Hazards. Cambridge University Press, Cambridge,
294pp.
Hays W W, Van Essche L and Maranzana F, 1991. SEISMED and IDNDR:
Opportunities to reduce the risk from earthquakes and other natural
hazards. Episodes 14(1): 15-18.
Mogi
K and Oyagi N, 1991. Prediction and prevention of geological hazards. Episodes 14(3): 293-298.
Rahn
P H, 1986. Engineering Geology, an environmental approach. Chapter
11, Earthquakes, Elsevier, New York.
The
Open University, 1981. Block 2 Earth Structure earthquakes, seismology
and gravity. The Open University, Milton Keynes, UK.
UNESCO, 1991. Standing up to natural disasters: 33-34.
Edgecumbe Earthquake References
Beanland S, Berryman K R and Blick G H, 1989 Geological Investigations
of the 1987 Edgecumbe earthquake sequence. New Zealand Journal
of Geology and Geophysics, 32: 31-42.
Berryman K and Beanland S, 1989. Evaluation of seismic hazard
on the Rangitaiki Plains, New Zealand. New Zealand Journal of
Geology and Geophysics, 32: 185-190.
Franks C A M, Beetham R D and Salt G A, 1989. Ground damage and
seismic response resulting from the 1897 Edgecumbe earthquake,
New Zealand. New Zealand Journal of Geology and Geophysics, 32:
135-144.
Lowry M A, Ede S C and Harris, 1989. Assessment of seismic intensities
resulting from the 1987 Edgecumbe earthquake, New Zealand, and
implications for modernising the intensity scale. New Zealand
Journal of Geology and Geophysics, 32: 145-153.
Smith E G C and Oppenheimer C M M 1989. The Edgecumbe earthquake
sequence: 1987: 1987 February to March 18. New Zealand Journal
of Geology and Geophysics, 32: 31-42.
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