Volcanoes: Eruptive Patterns and Types

Classification of Volcanoes

• Volcanoes can be classified into three primary forms: Shield, Cinder Cone/Scoria Cone, and Composite/Stratovolcanoes.

Shield Volcanoes

• Characterized by a wide base and a broad summit, resembling a warrior's shield.
• Composed primarily of mafic magma, resulting in less explosive eruptions.

Cinder Cone/Scoria Cone Volcanoes

• Form steep conical hills composed of debris ejected from a volcanic vent.
• Typically have eruptions that are short-lived and localized.

Composite Volcanoes/Stratovolcanoes

• Display steep sides formed by alternating layers of lava flows and pyroclastic materials.
• Comprised mainly of felsic magma, leading to more explosive eruptions.

Types of Lava Flow

• Lava Flow: Mass of lava flowing downslope; distinct from magma, which exists beneath the crust.
• Andesitic Lava Flow: Forms andesite rock; typically more viscous than basalt.
• Rhyolitic Lava Flow: Results in the formation of rhyolite rock; usually has a high viscosity.
• Basaltic Lava Flow: Creates basalt rock; flows in thin, broad sheets due to low viscosity.

Lava Characteristics

• Pahoehoe Flows: Smooth, unbroken lava flows; surfaces resemble twisted ropes.
• Aa Flows: Rough, jagged lava surfaces with sharp edges; named for their stony appearance.

Lava Conduits

• Lava Tubes: Cave-like structures that transport lava from the vent to the flow's edge.

Pyroclastic Materials

• Composed of ejected materials including pulverized rock, ash, and gases from explosive eruptions.
• Volcanic Block: Solid rock fragments expelled during an eruption.
• Volcanic Bomb: Semi-molten rock ejected from a volcano.

Pyroclastic Flows and Surges

• Pyroclastic Flow: Dense mixture of hot gas, rock particles, and lava droplets moving in a laminar flow.
• Pyroclastic Surge: Rapid, turbulent flow of gas, rock particles, and lava droplets with high velocity.

Tephra

• General term for fragments of volcanic rock and lava ejected into the air, varying in size.
• Tephra Flow: Consists of volcanic materials categorized by size (ash: <2 mm, lapilli: 2-64 mm, blocks/bombs: >64 mm).

Lahars

• Mudflows consisting of water, volcanic ash, and debris, resembling flowing wet concrete.

This flashcard quiz focuses on the classification of volcanoes based on their eruptive patterns and forms. You'll learn about shield volcanoes, cinder cone volcanoes, and composite volcanoes, along with key definitions and characteristics. Test your knowledge on volcanic types and their eruptions!