Maar

Maar USGS

Devil Mountain Lakes

maare

WeinfelderMaar

SchalkenmehrenerMaar

20170521 02 Schalkenmehrener Maar 04

Maar is a type of volcanic crater that is formed by a phreatomagmatic eruption, a volcanic eruption characterized by the interaction of groundwater with magma. These craters are typically shallow, broad, and surrounded by a ring of volcanic debris. Maars are found worldwide and represent some of the most common volcanic landforms on Earth. They are particularly noted for their circular shape and often fill with water to form natural lakes. Understanding maars is crucial for volcanology, the study of volcanoes, as well as for assessing volcanic hazards.

Formation

The formation of a maar is initiated when magma rises through the crust and comes into contact with groundwater. This contact causes the water to flash to steam, leading to a series of explosive eruptions. The explosions create a wide, shallow crater at the surface. The size and shape of a maar can vary significantly, depending on the volume of magma involved, the depth of the groundwater, and the composition of the surrounding rock.

Characteristics

Maars are characterized by their circular to oval shape and low rim composed of volcanic ash, lapilli (small volcanic rocks), and other ejecta. The crater floor is typically below the surrounding ground level and may be filled with water, creating a maar lake. The surrounding area may be covered with a blanket of tephra, the material ejected during the eruption.

Examples

One of the most famous examples of a maar is Laacher See in Germany, which formed around 12,900 years ago. Another well-known maar is Ukinrek Maars in Alaska, which formed as a result of eruptions in 1977.

Ecological and Geological Importance

Maars play a significant role in the local ecosystem as they often become lakes that provide habitat for various species. Geologically, they offer insights into the eruptive history of an area and the interaction between magma and groundwater. Studying maars can also help in understanding the potential volcanic hazards in regions with volcanic activity.

Hazards

While maars themselves are not typically associated with ongoing volcanic activity, their formation indicates the presence of magma near the surface and the potential for explosive eruptions. Understanding the formation and distribution of maars is essential for volcanic hazard assessment and planning in volcanic regions.