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Lecture 10

Geography 1100 Lecture Notes - Lecture 10: Mount St. Helens, Magma Chamber, Wave Shoaling

Course Code
GEOG 1100
Barry Tepperman

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Notes November 13, 2012
Lava ows with dates determined by radiometric techniques
+ Normal Magnetic Polarity
- Reverse Magnetic Polarity
Earth magnetic eld changes every many thousand years, this is
determined when lava is released from earths crust-> orientation of
atoms determines magnetic direction that existed during time
Isostatic Adjustment-
Two continental block collision causes very high mountains
Landforms resulting form volcanism
Batholith- magma chamber that cools in place- ex: granite
Mount Saint Helens- Erupted may 18, 1980
Erupted with force the blew o/ top and side of the mountain
Krakatoa- 1883 blast, darkened sky in Jakarta 150km away
Created title wave nearly 40 m high
-created sound in australia 2000km away, ask went into lithosphere,
cooled earth by several degrees,
-Discharged 20 cubic kilometers into atmosphere, created hole 300m
Earthquake waves-
Alaskan Earthquake- generated tsunami
Ground underneath liqueed, causing many buildings to sink, blocks of
earth sunk into ground
-lifted coastline
-middle of ocean small waves,
as wave approaches coast, wave slows down, gradually becomes
higher and higher
As tsunami approaches coast and waters become shallow, wave
shoaling compresses the wave and its velocity slows.
Japan Earthquake 8.9-
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