Causes
Volcanoes are points in Earth's crust where ruptures occur, causing lava, ash, rocks, and gas to erupt during seismic activity. They are typically located along the borders of tectonic plates in the lithosphere. Changes in pressure and density within the magma chamber beneath a volcano can force lower-density lava and rocks to rise, sometimes explosively. Over 75% of active volcanoes are situated in the Pacific “Ring of Fire”, a region known for its high geological activity due to the meeting of tectonic plates.
Consequences
Volcanoes on land pose significant danger to life, especially when located near inhabited areas. The famous example of Mount Vesuvius in Italy illustrates this risk; it destroyed two cities thousands of years ago and still poses a threat to millions of nearby residents today. Immediate physical threats from an eruption include the destruction caused by lava and rocks, but volcanic gases, such as sulphur dioxide, present respiratory hazards. Ash from eruptions can travel kilometers, driven by wind, creating respiratory risks and posing a danger to aircraft as fine ash particles can damage equipment.
Classification
Volcanoes are classified as active, dormant, or extinct based on their activity levels. Determining activity status can be challenging, as a volcano might be active beneath the surface without visible signs. Historical records play a key role; volcanoes that have erupted recently are more likely to do so again, though the intervals between eruptions can span years or centuries.
Satellite data
Satellites are crucial for observing active volcanoes, capturing optical and radar imagery of eruptions, and assessing damage from lava and rocks. Tracking the ash plume helps identify if people are at risk within its path. Due to the hazardous conditions of an eruption, satellite data may provide the first observations of the affected area as it may not be safe for aircraft or ground traffic. Radar data also supports long-term studies by monitoring ground movement that may signal upcoming seismic activity leading to potential eruptions.