VOCABULARY
Epicenter:
the point on
Earth’s surface directly
above the focus of an
earthquake.
ACTIVITY TWO
T
HE
P
LOT
T
HICKENS
: P
LOTTING
E
ARTHQUAKE
F
OCI IN
T
HREE
D
IMENSIONS
RA T I ONA L E
This activity graphically illustrates the patterns in the distribution of
earthquake foci in one relatively small area.
F OCU S QU E S T I ON
What would the pattern of earthquakes in one region look like if it
could be observed in three dimensions over a period of time?
OB J E C T I V E
Students will plot location and depth for one group of earthquakes and
observe their relationships.
MA T E R I A L S
for the teacher
Q
One copy of Master 3.4d, Central Japan (2 pages, left and right)
Q
Stiff cardboard, 30 cm x 60 cm (1 ft. x 2 ft.)
Q
Phillips screwdriver to punch holes for hanging
Q
Four pieces of cord or other support (See Teacher Preparation.)
Q
Glue or transparent tape
Q
Wall map of Japan or student atlases
for each small group
Q
One copy of Master 3.4d, Central Japan (2 pages, left and right)
Q
One copy of Master 3.4e, Selected Earthquakes Since 1980, Japan
Q
Pencils, pens, and metric rulers
Q
Transparent tape
Q
Small craft beads such as 12 mm or 8 nun
Q
Dental floss or other strong, fine string
Q
Scissors
Q
One size 8-d nail
P ROC E DUR E
Teacher Preparation
Use a copier to enlarge the two-part map until it can cover most of the
cardboard. Glue or tape the map to the top side of the cardboard.
Attach cord to the four corners and hang it from the ceiling, or rest it
on supports above the floor at a height that will be about eye level for
most students. Make standard-size copies of the two-part map for desk
use.
Focus (pl. foci):
the point within the
Earth that is the origin of an
earthquake, where strain energy is
first released as wave energy.
Magnitude:
a number that
characterizes the size of an
earthquake by recording ground
shaking on a seismograph and
correcting for the distance to the
epicenter of the earthquake.
Magnitude is expressed in Arabic
numbers.
A G U
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F E M A
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