This activity will help you practice valuable graphing skills which are necessary to being an Emergency Response Team member.

Beginning in May and throughout June, scientists collected seismic data on Mt. Pinatubo. Use this data to create three line graphs. You will need graph paper, a pencil and a ruler.

• On the "y" axis create a scale from 0 to 2000 and label this axis, "Total Number of Events."
• On the "x" axis, create a scale with 32 marks. List the dates upon which the events were recorded and label this axis, "Date." The dates go from May 16 to June 16 (32 days)
• Above each date place a dot for the number of events recorded on that day. Above 21-May-1991 on the "x" axis, for instance, put a dot across from 144 on the "y" axis. Plot all the data. Connect the dots.

Date	Total Number of Events	Observation Log
16-May-91	53
17-May-91	49
18-May-91	38
19-May-91	98	Steam clouds
20-May-91	120	Series of small hydrothermal "burps"
21-May-91	144	Small hydrothermal explosion; steam clouds and small amounts of tephra ejected 300 to 500 meters
22-May-91	88
23-May-91	66
24-May-91	78
25-May-91	92
26-May-91	134	Small amounts of tephra ejected 100-200 meters
27-May-91	34
28-May-91	89
29-May-91	92
30-May-91	101
31-May-91	61
1-Jun-91	89
2-Jun-91	94
3-Jun-91	135	Ash ejection lasting for 30 minutes
4-Jun-91	156	Ash ejections
5-Jun-91	167
6-Jun-91	178
7-Jun-91	1500	Low frequency volcanic quakes; magma nearing the surface
8-Jun-91	1776	Explosion-type earthquake
9-Jun-91	1895	Violent eruption; pyroclastic flows to 5 kilometers
10-Jun-91	685
11-Jun-91	1203	Harmonic tremors
12-Jun-91	1565	Intense seismic activity and explosions followed by 3 major explosions, ash, pumice, and ejected fragments
13-Jun-91	1706	Violent eruption triggering heavy ashfalls
14-Jun-91	1905	Fourth major eruption; vertical ash cloud 25 kilometers; pyroclastic flows 15 kilometers from source
15-Jun-91	1843	Two explosions, pyroclastic flows moving between 70 to 80 km/hr; vertical ash cloud 40km high
16-Jun-91	856	Activities decline both in frequency and magnitude

 

1. Looking at this data over the weeks, pay attention to the peaks and valleys in the line graph. Is there a pattern? What does the pattern or lack of pattern tell you about how hard it is to predict volcanic eruptions?

2. Read the observation log for these times and write notes on your graph about what was observed. On your graph, circle some of the peaks where the seismic activity was followed by observations of volcanic activity.

---

Privacy Statement and Copyright © 1998-2005 by Wheeling Jesuit University / Challenger Learning Center^®. All rights reserved.