Volcanic activity

Volcanoes are formed when molten rock (magma) from beneath the Earth’s crust rises to the surface. This can occur for several reasons:

Tectonic plate movements: At divergent boundaries, plates move apart, and magma rises to fill the gap. At convergent boundaries, one plate is forced under another in a process called subduction. The subducting plate melts and forms magma, which can rise to the surface.
Hotspots: These are areas in the middle of tectonic plates where magma rises to the surface. The Hawaiian Islands are an example of a hotspot chain.

Volcanoes are commonly found at:

Convergent boundaries: Where two plates collide, especially when an oceanic plate is forced under a continental plate. The Pacific Ring of Fire is a prime example.
Divergent boundaries: Where two plates move apart, such as the Mid-Atlantic Ridge.
Hotspots: As mentioned, these can be in the middle of tectonic plates.

Examples of volcanic eruptions

Tectonic plate movements: The eruption of Mount St. Helens in the United States in 1980 was caused by subduction of the Juan de Fuca Plate beneath the North American Plate.
Hotspots: The eruption of Kilauea in Hawaii in 2018 was caused by a hotspot.

Volcanic eruptions can lead to a number of hazards, including:

Lava flows: Molten rock that can destroy everything in its path.
Pyroclastic flows: Fast-moving currents of hot gas and volcanic matter.
Ash fall: Fine particles that can affect air travel, human health, and agriculture.
Lahars: Mudflows formed when volcanic debris mixes with water.
Tsunamis: If the eruption or a landslide caused by an eruption displaces a large amount of water.

Examples

Lava flows: The 2018 eruption of Kilauea in Hawaii resulted in significant lava flows that destroyed homes and infrastructure.
Pyroclastic flows: The 1985 eruption of Nevado del Ruiz in Colombia produced pyroclastic flows that killed thousands of people in the town of Armero.
Ash fall: The 2010 eruption of Eyjafjallajökull in Iceland released an ash cloud that disrupted air travel across Europe.
Lahars: The same 1985 eruption of Nevado del Ruiz also produced lahars that contributed to the devastation of Armero.
Tsunamis: The 1883 eruption of Krakatoa in Indonesia generated a massive tsunami that killed tens of thousands of people.

There are a number of things you can do to prepare for a volcanic eruption, including:

Have an evacuation plan: Know the routes and have a plan in place.
Assemble an emergency kit: Include masks to prevent ash inhalation, goggles, water, non-perishable food, and other essentials.
Stay indoors: During an ashfall, it’s safer inside.
Protect property: Clear roofs of ash, which can be heavy and cause collapses.

Examples of volcanic eruption preparation

Evacuation plans: Before the 1991 eruption of Mount Pinatubo in the Philippines, timely evacuation plans based on scientific predictions saved thousands of lives.
Emergency kits: In areas prone to volcanic activity, like parts of Indonesia or Japan, local governments often distribute guidelines on what to include in emergency kits.

To monitor and assess volcanic activity, experts use:

Seismographs: To detect earthquakes that indicate magma movement.
Tiltmeters and GPS: To measure ground deformation.
Gas sensors: To measure gases emitted from the volcano, like sulfur dioxide.
Thermal cameras: To detect heat around the volcano.
Satellite imagery: To monitor changes in the volcano’s shape and track ash clouds.

Examples of equipment used to assess volcanic activity

Seismographs: Before the 1980 eruption of Mount St. Helens, seismographs detected increased earthquake activity, signaling the upcoming eruption.
Tiltmeters and GPS: The swelling of Mount St. Helens before its 1980 eruption was detected using these tools.
Gas sensors: Before the 2010 eruption of Eyjafjallajökull in Iceland, increased emissions of certain gases were detected.
Thermal cameras: These have been used in various volcanic regions, like the Andes in South America, to monitor heat variations around volcanoes.
Satellite imagery: Satellites were crucial in monitoring the ash cloud