Unrest

Prior to an eruption, volcanoes are said to be in a state of volcanic unrest when magma or its associated fluids are interacting with country rock, groundwater or hydrothermal fluids to produce noticeable signs. Those signs may include various types of seismicity (earthquakes), ground deformation, degassing (the release of magmatic gases through the ground) and/or changes in geothermal systems. Other processes that are not related to magma movement, such as tectonic fault movement or hydrothermal system changes, often appear very similar to signs of volcanic unrest. Until these can be confidently discounted from being caused by magma movement, they are considered to be potential unrest.