Hydrogeomorphic Effects of Explosive Volcanic Eruptions on Drainage Basins

• Published in: Annual review of earth and planetary sciences 2014-01, Vol.42 (1), p.469-507
• Main Authors: Pierson, Thomas C, Major, Jon J
• Format: Article
• Language: English
• Subjects: Basins; Damage; Density; Density currents; Disturbances; Drainage; Drainage basins; Explosions; explosive volcanic eruptions; geomorphic recovery; Gravel; Lava; runoff; Sediment discharge; Sediment yield; Sediments; Socioeconomic factors; Vegetation; Volcanic activity; volcanic drainage basins; Volcanic eruptions; volcaniclastic sedimentation; Volcanoes
• ISSN: 0084-6597; 1545-4495
• DOI: 10.1146/annurev-earth-060313-054913

Explosive eruptions can severely disturb landscapes downwind or downstream of volcanoes by damaging vegetation and depositing large volumes of erodible fragmental material. As a result, fluxes of water and sediment in affected drainage basins can increase dramatically. System-disturbing processes associated with explosive eruptions include tephra fall, pyroclastic density currents, debris avalanches, and lahars-processes that have greater impacts on water and sediment discharges than lava-flow emplacement. Geo-morphic responses to such disturbances can extend far downstream, persist for decades, and be hazardous. The severity of disturbances to a drainage basin is a function of the specific volcanic process acting, as well as distance from the volcano and magnitude of the eruption. Postdisturbance unit-area sediment yields are among the world's highest; such yields commonly result in abundant redeposition of sand and gravel in distal river reaches, which causes severe channel aggradation and instability. Response to volcanic disturbance can result in socioeconomic consequences more damaging than the direct impacts of the eruption itself.