Geochemical evidence of oceanic iron fertilization by the kasatochi volcanic eruption in 2008 and the potential impacts on pacific sockeye salmon

The Kasatochi volcanic eruption that occurred in the central Aleutian Islands in Alaska, USA, in August 2008 is thought to have induced a massive diatom bloom in the iron-limited waters of the Gulf of Alaska, which potentially affected the oceanic food web by increasing the abundance of zooplankton and sockeye salmon Oncorhynchus nerka in the northeast Pacific Ocean. We report the first seawater experiments involving volcanic ash ejected from the Kasatochi eruption, showing that the ash released 61 to 83 nmol Fe, 374 to 410 nmol NO3-, 5 to 6 nmol PO43- and 170 to 585 nmol SiO2 when it contacted seawater. Our study suggests that the amount of iron released from Kasatochi ash (an increase of 2.0 to 2.8 nM Fe) was indeed sufficient to cause the observed phytoplankton bloom in the northeastern Pacific Gyre, while the impact of macronutrient release was minimal. We further evaluated the multiple, interdependent processes in the oceanic food web related to the diatom bloom, involving the ocean survival of juvenile salmon that entered the northeast Pacific Ocean in the summer of 2008

Geochemical evidence of oceanic iron fertilization by the kasatochi volcanic eruption in 2008 and the potential impacts on pacific sockeye salmon

The Kasatochi volcanic eruption that occurred in the central Aleutian Islands in Alaska, USA, in August 2008 is thought to have induced a massive diatom bloom in the iron-limited waters of the Gulf of Alaska, which potentially affected the oceanic food web by increasing the abundance of zooplankton and sockeye salmon Oncorhynchus nerka in the northeast Pacific Ocean. We report the first seawater experiments involving volcanic ash ejected from the Kasatochi eruption, showing that the ash released 61 to 83 nmol Fe, 374 to 410 nmol NO3-, 5 to 6 nmol PO43- and 170 to 585 nmol SiO2 when it contacted seawater. Our study suggests that the amount of iron released from Kasatochi ash (an increase of 2.0 to 2.8 nM Fe) was indeed sufficient to cause the observed phytoplankton bloom in the northeastern Pacific Gyre, while the impact of macronutrient release was minimal. We further evaluated the multiple, interdependent processes in the oceanic food web related to the diatom bloom, involving the ocean survival of juvenile salmon that entered the northeast Pacific Ocean in the summer of 2008

Ground-Coupled Airwaves at Pavlof Volcano, Alaska, and their Potential for Eruption Monitoring

An abnormally high number of explosion quakes were noted during the monitoring effort for the 2007 eruption of Pavlof Volcano on the Alaska Peninsula. In this study, we manually cataloged the explosion quakes from their characteristic ground-coupled airwaves. This study investigates how the ground-coupled airwaves might be used in a monitoring or analysis effort by estimating energy release and gas mass release. Over 3 × 104 quakes were recorded. The energy release from the explosions is approximated to be 3 × 1011 J, and the total gas mass (assuming 100 % water) released was 450 t. The tracking of explosion quakes has the potential to estimate relative eruption intensity as a function of time and is thus a useful component of a seismic monitoring program

Factors Contributing to Volcano Lateral Collapse

Many factors can lead to volcano lateral collapse, which can produce devastating debris avalanches that travel up to several tens to over 100 km and cover hundreds to more than a thousand km2 with debris. Volcanic lateral collapses are severe hazards because of their destructive power and size, and sudden onset. Although their frequency of occurrence is not as high as those of smaller volcanic mass movements, such as rock falls and lahars, globally large collapses ≥0.1 km3 have occurred at least five times per century over the last 500 years. A large variety of destabilizing factors such as over-steepened slopes, magma intrusions, hydrothermal activity, climate fluctuations, deformation of the basement, and faulting can create the conditions for volcano collapse. Once a volcano reaches its critical point, a mechanism is necessary to trigger the failure event. We present the state-of-the-art of the knowledge acquired in the last few decades concerning the causes of large-scale volcanic failures to better understand the triggers, preparatory factors, and timing of volcano lateral collapse