No abstract

Volcanic eruptions can generate widespread deposits of ash that are subsequently subjected to erosive forces which causes detrimental effects on ecosystems. We measured wind erosion of the freshly deposited Eyjafjallajökull ash at a field site the first summer after the 2010 eruption. Over 30 wind erosion events occurred (June-October) at wind speeds > 10 m s−1 in each storm with gusts up to 38.7 m s−1. Surface transport over one m wide transect (surface to 150 cm height) reached > 11,800 kg m−1 during the most intense storm event with a rate of 1,440 kg m−1 hr−1 for about 6½ hrs. This storm is among the most extreme wind erosion events recorded on Earth. The Eyjafjallajökull wind erosion storms caused dust emissions extending several hundred km from the volcano affecting both air quality and ecosystems showing how wind erosion of freshly deposited ash prolongs impacts of volcanic eruptions.

Abstract.Results between these experiments with the ice core records shows that when deep water is turned on, much of the YD termination warming is achieved. The increase in precipitation is underestimated because of a model tendency to overestimate summertime precipitation, which obscures the dominantly wintertime response to the specified forcing. The winter storm track shift toward Greenland contributes much of the climate change at the YD termination.

Samples of the subglacial lake in the crater of the tholeiitic basaltic caldera Grfmsv0tn in Iceland were obtained by using a hot-water drill to sink two boreholes through the 250-m-thick ice shelf coveting the lake. The lake generally shows an increase in solutes with increased depth, as solutes are added from the lake's bottom and dilute glacial meltwater is added continuously from above. The crater lake temperature ranges from 0øC in the upper part to temperatures of IøC to 4øC near the bottom of the lake. The lake water pH ranges between 7.0 and 5.7. The crater lake is assumed to be closed, with respect to volatile components released from subsurface magma, except for periodic draining by j0kulhlaups. From the periodicity and water chemistry of the j0kulhlaups, we have estimated the volcano's average release rates of carbon, sulfur, chlorine and fluorine between 1954 and 1991 and corrected these rates for dissolution of bedrock into the lake water and seepage of solutes to groundwater. The corrected mean release rates are 5.3 x 107 kg C yr 4, 5.3 x 10 • kg S yr 4, 6.6 x l O 5 kg C1 yr 4, and 1.5 x 10 • kg F yr '•. The emission rate estimates for Grfmsv0m, one of the most active volcanoes in Iceland, are the longest integrated estimates obtained for an active volcano and are equal to or lower than those of other major active volcanoes worldwide. This difference may imply that published release rates for other volcanoes are overestimated, because they are usually not integrated over time. The values of the S/C1 and F/C1 ratios for noneruptive periods are 0.53 +_ 0.20 and 0.013 +_ 0.003, and for the two eruptive events are 0.69 and 2.14, and 0.034 and 0.041, respectively. The response of the elemental ratios to eruptive events, followed by the return to lower ratios, supports the assumption of steady state, because no long=term accumulation of volatiles occurs. The energy output from the volcano, estimated from the amount of ice melted by hydrothermal heat, is 4250 MW over the last four decades. Using the energy output to calculate magma solidification rates and maximum possible volatile release rates, we observe that emissions of F and S are strongly suppressed at Grfmsv0m, while a significant portion of available C1 and C are released.These calculations also reveal that coverage of a volcano by a glacier, and subsequent raising of the water table, may cause significant scrubbing of magmatic gases so that these gases do not reach the atmosphere. IntroductionEstimating the volatile release rates of active volcanoes is of paramount importance to understanding the long-term volatile budgets in the Earth's atmosphere, as well as to enable the short-term prediction of catastrophic eruptions. Current global estimates of the contribution of carbon to the atmosphere by volcanoes are 42.0 x 109 kg C yr 4 [Oerlach, 1991], and 18.0 x 10 •ø kg C yr 4 [Williams et al., 1992]. WillJains et al. [1992] have argued that noneruptive degassing accounts for 52% and eruptive degassing accounts for 48% of total carbon release from v...