Volcanoes - Geology Worksheet (Page 4 of 4) in pdf

Volcanoes - Geology Worksheet Page 4

Physical Geology 101

Tuff Rings and Maar Craters

Explosive eruptions of pyroclastic material may leave a ring of debris around a vent, called a tuff ring.

Example: ____________________________

Similar explosive eruptions may occur when lava flows cover over a lake, forming a circular depression at the

surface called a maar crater, surrounded by ejecta and which may fill with water to form a circular lake.

Lava Domes

After an eruption, a volcano doesn't necessarily become inactive. It may start to push up the crater or caldera,

forming a mound called a lava dome.

Examples: ________________________

and

________________________

What is the world’s largest lava dome? __________________________

Predicting Eruptions

What are the three categories for volcano activity?

1. __________________ (is erupting or has erupted in recent history)

2. __________________ (has not erupted in recent history but has the potential to erupt)

3. __________________ (shows no signs of activity)

Some tell-tale signs of an impending eruption include:

1. Sudden bulging inside the crater due to the magma chamber filling up (measured with a tiltmeter).

2. Increased minor earthquake activity.

3. Increased water temperature in the crater lake.

4. Increased gaseous emissions.

FINAL QUESTION:

What is the most active volcano in the Cascades?

__________________________________

Volcanoes - Geology Worksheet Page 4