Classification of Volcanoes Based on Activity
| Type | Description | Examples |
|---|---|---|
| Active | Volcanoes that have erupted recently. | Kīlauea in Hawaii, Mount Etna in Italy, Mount Stromboli in Italy, Barren Island in India |
| Dormant | Volcanoes that have been inactive for a long period but may erupt again in the future. | Mount Kilimanjaro in Tanzania, Africa, and Mount Fuji in Japan |
| Extinct | Volcanoes considered unlikely to erupt in the future. | Calupin Volcano in New Mexico, Ben Nevis in the UK, Mount Thielsen in Oregon |
Underwater Volcanoes
Underwater volcanoes, also known as submarine volcanoes, form when magma from the Earth’s mantle erupts on the ocean floor. Over time, these eruptions can create volcanic islands or underwater mountains known as seamounts.
Examples:
- Axial Seamount, located along the Juan de Fuca Ridge in the Pacific Ocean
- Loihi Seamount, situated near Hawaii
- Fukutoku-Okanoba Submarine Volcano, found north of Japan’s South Iwo Jima Island
Fuel-Coolant Interaction:
When magma seeps into seawater slowly, a steam layer forms that insulates and cools its surface. If magma erupts rapidly with volcanic gases, this steam layer collapses, allowing direct contact between magma and cold water, leading to a process called fuel-coolant interaction.
Types of Volcanic Eruptions
Volcanic eruptions are classified based on the nature of the opening through which magma escapes:
1. Fissure Eruptions
- Occur along a crack or a series of fissures.
- Lack of explosive activity.
- Result in the formation of lava plateaus or plains.
- Example: Columbia Plateau in the USA (Miocene epoch).
2. Central Eruptions
- Eruption occurs through a central vent.
- Ejects ash, rock fragments, and lava, forming cone-like structures around the vent.
Types of Central Eruptions
| Type | Characteristics | Examples |
|---|---|---|
| Hawaiian | Calm eruptions with minimal explosive activity. | Mauna Loa and Kīlauea, Hawaii |
| Strombolian | Moderate intensity with rhythmic or continuous eruptions. | Stromboli Volcano |
| Vulcanian | Moderately explosive, ejecting significant gas and ash. | Mount Vulcano, Lipari Island |
| Pelean | Produces avalanches of gas, ash, and rock fragments (Nuées ardentes). | Mount Pelée, Martinique |
| Plinian | Highly viscous lava causing extremely violent eruptions. | Mount St. Helens |
Major Active Volcanoes of the World
| Volcano | Location | Key Features |
|---|---|---|
| Mount Vesuvius | Southern Italy, near Naples | The only active volcano on mainland Europe; classified as a compound volcano. |
| Kīlauea | Hawaii, USA | Among the most active volcanoes globally. |
| Sakurajima | Kyushu, Japan | An active stratovolcano. |
| Pacaya Volcano | Guatemala | A basaltic complex volcano. |
| Arenal Volcano | Northwestern Costa Rica | A stratovolcano. |
| Santa Maria | Western Guatemala | Hosts Santiaguito, one of the world’s most active lava dome complexes. |
| Stromboli | Italy | Known as the “Lighthouse of the Mediterranean,” it is one of the world’s most active volcanoes. |
| Lascar | Northern Chile | A stratovolcano. |
| Mount St. Helens | Washington, USA | An active stratovolcano and part of the Pacific Ring of Fire. |
| Mount Taal | Philippines | The smallest active volcano globally. |
| Galeras | Southwestern Colombia | An andesitic stratovolcano within an older volcanic complex. |
| Mount Etna | Sicily, Italy | The highest Mediterranean island mountain and the world’s most active stratovolcano. |
| Mount Erebus | Antarctica | Known for its persistent lava lake. |
| Heard Island | Australia | Home to Big Ben, an active volcano. |
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