Impact of volcanic climate perturbation caused by Laacher See eruption onto the proximal environment and terminal eruptive mechanisms
Final Report Abstract
A strong climate impact caused by LSE is highly plausible judging from the high S-concentrations of the magma and the fact that the eruption column reached the stratosphere for many hours during the Plinian eruptive phases resulting in a potential input of at least 20 Tg SO2. Our aim was to document major climate impact by indicators of extraordinarily strong erosive processes within the devastated area close to vent. We have focused on complex high-resolution correlations between different topographic settings in order to temporally synchronize erosive patterns on higher ground with changes in the discharge of Rhine River (RR) and its tributaries. We can unequivocally verify that extreme precipitation must have occurred prior to the final eruptive pulse of ULST-C and thus prior to the very end of LSE causing both (1) major gully erosion on higher ground as well as (2) severe flooding within the RR system. The gully erosion started and ended abruptly roughly synchronously within the entire area. The severe erosion continued for several months and was much more powerful than during the preceding eruptive phases and also compared to the subsequent erosion caused by the Younger Dryas cooling period which lasted c. 1140 years. Major weather deterioration caused by LSE must have started with a delay of 6 or more months (in the fall or early winter) following massive SO2 influx into the stratosphere. These results are corroborated by tree ring and varve studies that postulate that the conditions were still normal during the summer when LSE took place but deteriorated afterwards for several years.
