Earthquake data

Earthquake data

Pencil and paper
Overview
Using this Resource
Connecting to the Curriculum
Marking Student Responses
Further Resources
This task is about using data to find out more about earthquakes.
An earthquake struck the South Island of New Zealand about 10:17 a.m. yesterday morning. Below are the seismograph records from three different recording stations; A, B, and C. (See map of the South Island for their location).
a)
For each station measure (in millimetres) the distance between the beginning of the P wave and the beginning of the S wave.
 
Station A: distance between P and S wave = __________ mm.
 
Station B: distance between P and S wave = __________ mm.
 
Station C: distance between P and S wave = __________ mm.
 
b) The distance between the P and the S wave, i.e., the information from part a) can be used to calculate how far each station was from the epicentre of the earthquake. Use Table I below to work out these distances.
 
Table I - Relationship between time and distance between P and S waves and distance from epicentre
Distance between P and S waves (mm) 5 10 15 21 26 30 36 41
Time between P and S waves (seconds) 4 7 10 14 17 21 24 28
Distance from epicentre (km) 25 50 75 100 125 150 175 200
 
 
i) Station A was __________ km away.  
 
ii) Station B was __________ km away.  
 
iii) Station C was __________ km away.
 
 
c)
Use the distances you calculated in b) above, and the scale on the map of the South Island to show where the epicentre of the earthquake was located. Use a compass to find this point on the map of the South Island, then mark this point with an X.
 
d)
Another seismograph recording station which is further away from the epicentre than A, B, or C is located at point D in the South Island (see map). In the space below draw a recording that could have come from this station, and label the P and S waves. Your drawing only needs to be an approximation of such a recording.
 
 
Station D
 
 
 
 
 
 
 
 
 
e) Use the data from Station A to complete the statements to calculate the magnitude of this earthquake.
 
i)  Use Table I to calculate the time difference between the arrival of the P and S waves for Station A.
 
     Time difference = __________ seconds
 
 
ii)  Measure the maximum amplitude of the S wave (on the seismograph record) in Station A in millimetres.
 
     Amplitude of S wave = __________ mm
 
 
  iii) On the diagram below draw a line between these two points to find the earthquake's magnitude.
 
     
S-P Interval (time difference in seconds between waves) Magnitude Amplitude (max height of wave in mm)
 
iv) What is the magnitude of this earthquake? __________
 
Task administration: 
Equipment:
Ruler; compass.
  • This task assesses students' ability to calculate and process information on earthquakes.
  • This task can be completed with pencil and paper. 
Level:
5
Curriculum info: 
Science, Communicating in science, Planet Earth
Keywords: 
Earth systems, earthquakes
Description of task: 
This resource requires students to process information on an earthquake. This entails calculating the distance that the recording stations are from an earthquake's epicentre, locating the epicentre, calculating the magnitude, and answering general questions on earthquakes.
Curriculum Links: 
Science capabilities
The capabilities focus is brought about by the conversations you have and the questions you ask.
 
Capability: Interpret representations
Scientists represent their ideas in a variety of ways, including models, graphs, charts, diagrams and written texts. This resource provides opportunities to discuss ways different information about the same event can be presented, and how the reader needs to be aware of the purpose for each representation.
 
Science capabilities: 
Interpret representations
Answers/responses: 
a)

 

  

 

 Station A = 21 mm ± 1 mm
Station B = 26 mm ± 1 mm
Station C = 36 mm ± 1 mm
b)

 

  

 

 Station A = 100 km ± 5 km
Station B = 125 km ± 5 km
Station C = 175 km ± 5 km
c)

 

  

 

 Draws these arcs.

Identifies epicentre with an X.
d)

 

  

 

 Seismograph drawing shows:

  • Greater distance (more than 40 mm) between P and S waves.
  • Height of S wave is between 1 and 4 mm.
  • P and S waves labelled.
e)

 

 i)
ii)
iii)		 Time difference = 14 seconds.
Amplitude of S wave = 19 ± 1mm.
Magnitude = 4.4 ± 2 (or as calculated from answers in e)i) and ii)).

NOTE: Differences in printing may cause differences in measurement; please check all measurements.