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Sign up to attend a Papago Park extra credit field trip (worth 20 points).

Options:

Wed., April 16: 10-11AM or 4-5 PM

Thurs., April 17: 10-11AM or 2-3 PM

Today’s Lecture:Today’s Lecture: Chap. 9 Chap. 9 VolcanoesVolcanoes

Class presentations:

Cancer-causing gas in Beverly Hills CA - Michael Zara

Mt. Rainier - Nathan Policar

Intermediate volcanoes (cont.)

Calderas

Volcanic hazards

Case Study: Mt. Saint Helens

Economic aspects:

Hydrothermal activity

Mineral deposits

Volcanic Activity on Other Planets

a.a. Calderas Calderas

b.b. Lava domes Lava domes

summit crater greater than 1 km wide from collapse of summit

viscous felsic magma usually form after explosive eruption of gas-rich magma

Some Other Important Volcanic Features

Fig. 09.11ab

W. W. Norton

Volcano startsto erupt.

Full magmachamber

Main explosiveeruption

Magma chamberempties.

Newly formedcaldera

Collapsed blocks

Empty magmachamber

New volcaniccone grows.

Lake fillscaldera.

Ash and debris

Fig. 09.29b

© 1997 Birke Schreiber

Mount St. Helen’s

Lava dome

Case study: Mt. St. Helens

Case study:Mt. St. Helens

•Located in the Cascade volcanic range, NW US.

•Result of past/present subduction of oceanic crust in the Cascadia Trench

•Many volcanoes there are still active

9500’

8150’(1350’ shorter!)

Case study:Mt. St. Helens

Ejected nearly a cubic kilometer of ash & rock debris

59 deaths

Ash blown over 11 miles high!

Fig. 09.15

W. W. Norton

Fig. 09.16abc

W. W. Norton

Fig. 09.22e

Photo by J. Marso, U.S. Geological Survey

Volcanic mudflows

Mount Saint Helens

A lava dome

formed

in crater

after major

eruption.

Hydrothermal Systems:

Develop anywhere that fluids coexist with a heat source.

Typical heat source a magma intrusion.

Effects: Alteration of adjacent rocks and deposition of mineral deposits, often of economic importance.

Also a source of geothermal energy.

GENERAL FEATURES OF HYDROTHERMAL

SYSTEMS

Hydrothermal Springs: Natural Laboratories for studying microbial fossilization.

Grand Prismatic Spring

1: Lava flows

2: Ash falls

3: Ash flows

4: Mud flows

Videos: Types of Volcanic Eruptions

VENUS

Volcanoes Elsewhere in Solar System

MARS

Fig. 09.30a

JPL / NASA

Olympus Mons: Largest Volcano in the Solar System

Olympus Mons, Mars

Jupiter’s moon “Io”

From Scientific American, Feb 2000

Jupiter’s moon “Io”

Fig. 09.30b

JPL / NASA

Volcanic Eruptions in Progress on Io