Volcanoes and Earthquakes Overview

I said they hate to see me coming.

Volcano

Opening in Earth's crust releasing magma.

Active Volcano

At least 1,500 currently erupting worldwide.

Volcanic Eruptions

Approximately 50 eruptions occur annually.

Viscosity

Resistance of lava flow influenced by silica content.

Basalt

Low silica (48-55%), low viscosity lava.

Andesite

Medium silica (55-60%), higher viscosity lava.

Dacite

High silica (60-70%), high viscosity lava.

Rhyolite

Very high silica (70-77%), very high viscosity.

Cinder Cones

Mildly explosive volcanoes formed from basalt.

Shield Volcanoes

Broad, gently sloping volcanoes from basalt.

Composite Volcanoes

Alternating lava and ash, can be highly explosive.

Lava Domes

Non-explosive, formed from viscous dacite to rhyolite.

Calderas

Large, explosive depressions formed from collapsed volcanoes.

Lahars

Fast-moving mixtures of water and volcanic debris.

Pyroclastic Flows

Rapid, hot flows of rock and gas.

CO2 Emissions

Release of carbon dioxide from volcanic activity.

Fertile Soils

Mineral-rich soils from volcanic ash deposits.

Geothermal Energy

Energy harnessed from Earth's heat via magma.

New Land

Land formed by lava flows entering oceans.

Seismographs

Instruments detecting and recording earthquake activity.

Richter Scale

Measures earthquake magnitude based on energy release.

Elastic Rebound Theory

Explains how earthquakes occur due to stress release.

Epicenter

Point on surface directly above earthquake focus.

Focus

Location of maximum movement during an earthquake.

Fault Scarps

Steplike landforms formed by fault movement.

Fissures

Surface cracks without displacement from earthquakes.