Volcanoes, Earthquakes and Plate Tectonics Outline

August 29, 2003

1. Plate Tectonics theory

a. Lithosphere/ lithospheric Plates

b. Asthenosphere

c. Geography of the plates

d. Boundary Types

i. Convergent

A. Oceanic-Oceanic – Island Arcs, Igneous and Seismic

B. Oceanic-Continental – Continental Arc, Igneous and Seismic

C. Continental-Continental – Himalayan or Alpine, Seismic

ii. Divergent

A. Ocean ridges – Igneous and Seismic

1. Sea Floor Spreading

2. Magnetic Anomalies

iii. Transform

A. Sliding – California

e. Polarity

i. Curie Point

ii. Normal

iii. Reverse

2. Volcanoes

a. Types

i. Cinder Cone – Pyroclastic Material, some lava

ex. Wizard Island in Crater Lake

ii. Shield – Lava Flows, generally quiet eruptions

ex. Hawaii

iii. Composite or Stratovolcano – Pyroclastic and lava flows interlayered

ex. Mt. St. Helens

b. Volcanic structures

i. Craters and calderas

ii. Volcanic Necks

iii. Central Vents

iv. Fissures

c. Types of Lavas

i. Pahoe-hoe – Ropy

ii. Aa – Blocky

iii. Lava Lakes

iv. Pillow Lavas – Ocean Ridges

v. Topographic Inversion

e. Hot Spots

i. Can be used to tell plate movement

ii. Relatively stable over time

3. Earthquakes

a. Focus – Place in the Earth where the rupture occurs

b. Epicenter – Place on the Earth above the Focus

c. Seismic waves

i. P-waves

ii. S-waves

iii. Others

d. Seismograph

i. Modified Mercalli Scale – measure of intensity

ii. Richter Magnitude Scale – measure of magnitude

e. Average Travel Time Curve

f. Location of Epicenters

g. Benioff Zone