Volcanoes Overview and Classification

Volcanoes

• Volcanoes vary in height, shape, and slope, related to their magma composition.
• A volcano is an opening in the Earth's surface where molten rock, smoke, gases, and ashes erupt.
• Volcano parts include a main vent, parasitic cone, side vent, magma chamber, and volcanic ash.

Volcano Classification

• Active: Erupted within the last 600 years or 10,000 years ago.
• Inactive: Not erupted in the last 10,000 years.
• Dormant: Hasn't erupted for a long time, but might in the future.
• Extinct: Hasn't erupted for at least 100,000 years.

Volcano Types

• Shield Volcanoes: Broad, gently sloping sides, made of thin, runny basaltic lava, formed over hotspots, and have many vents. They erupt gently.
• Composite Volcanoes: Steep, made of layers of ash, tephra, and thick, sticky lava (andesitic). Erupt violently and have little lava flow, more pyroclastic material.
• Cinder Cones: Small, steep volcanoes made of volcanic debris that builds up around a vent. Erupt violently and are the most common and smallest type. They don't generally have vents. All are explosive volcanoes.

Types of Eruptions

• Phreatic/Hydrothermal: Steam driven, caused by hot rocks' contact with water, producing ash columns.
• Phreatomagmatic: From the contact of water and magma. Produces large ash columns and pyroclastic base surges.
• Strombolian: Weak to violent eruptions, fountain lava.
• Vulcanian: Tall eruption columns reaching 20 km high, lasting seconds to minutes.
• Plinian: Explosive eruptions with high rates of magma discharge, lasting minutes to hours. The largest eruptions that occur.

Importance of Volcanoes

• Disadvantages:
  • Lahars (mudflows).
  • Pyroclastic flows (glowing avalanches).
  • Damage to property.
  • Effects on the environment (climate change).
  • Loss of life.
• Advantages:
  • Fertile soil.
  • Tourism.
  • Creation of new land.
  • Building materials.
  • Geothermal energy.

Signs of Volcanic Eruptions

• Increased tremors.
• Increased steaming activity.
• Crater glows.
• Ground swells, ground tilt, and fissuring (magma intrusion).
• Localized landslides, rock falls, and landslides.
• Increase in temperature of hot springs.
• Noticeable variations in chemical content of springs.
• Drying up of springs.
• Development of new thermal areas.

Climate Change and Weather

• Weather: Short-term, fluctuating conditions influenced by various factors.
• Factors: Latitude, ocean currents, wind and air pressure, elevation/altitude, and relief.
• Important Elements: Temperature, humidity, rainfall, seasons, climate.
• El Niño & La Niña: Associated with warmer (El Niño) or colder (La Niña) water temperatures. El Niño can lead to heavy rains, and La Niña to dry conditions.

Stars

• Plasma: Fourth state of matter, ionized gas where electrons are ripped away. Stars are made of plasma.
• Brightness: Luminosity (total amount of light) versus apparent brightness (perceived from earth), depending on distance, affecting how we see stars in the night sky.
• Color: Depends on surface temperature of a star. Cooler = redder; hotter = bluer or whiter.
• Size & Mass: Stars are measured in comparison to our Sun, relative to the size and mass of our star.
• Constellations & Asterisms Patterns of stars. Asterisms are smaller groups/patterns within constellations. Helpful for navigation and relating to seasons and agricultural methods.