Using lake cores to improve the knowledge of volcanic activity at São Miguel Island (Azores) - Laboratory technician
REF nº : 1078/2019/ACORES
Lakes are natural traps of sediments and therefore an invaluable source of information for several areas of research including paleolimnology, climatology and volcanology. They record information about the evolution of lacustrine ecosystems, on time scales of several millennia, while also preserving deposits from instantaneous events such as landslides and volcanic eruptions. Lake sediment cores from volcanic areas usually provide a rich record of pyroclastic material deposited during explosive eruptions (tephra layers), which may be correlated with deposits on land. Furthermore, lake cores provide important records of distal volcanic eruptions, as lakes are more likely to preserve fine ash than the terrestrial environment which is prone to erosion.
In environments where the preservation of tephra on land can be particularly poor, for example in oceanic islands like the Azores, lakes may provide an invaluable record of a volcano’s eruptive history. However, the length of the record depends on the age of the lake and on the sedimentation rate. Information obtained from lake sediment cores can be used to evaluate eruption frequency and thus have considerable implications for volcanic hazard assessment. In addition lake core data can also be useful for physical volcanology studies as the thickness and grain size of tephra layers can help to constrain isopach and isopleth maps, which allow to estimate key eruptive source parameters (erupted volume, magnitude, column height, mass eruption rate, etc.) in more detail.
- Task 1: - Integration of the trainee in the working group and laboratory of the University of the Azores
- Learning of the methodologies to be used
- Task 2: - Collection of sediments from Areeiro lake (São Miguel Island), in collaboration with other research groups from the University of the Azores
- Task 3: - Detailed description of the collected cores
- Sampling of tephra layers along the cores and observation of samples with binocular microscope
- Carrying out of grain size and component analyzes
- Preparation of thin sections for observation under the optical microscope
- Task 4: - Establishment of stratigraphic correlations with subaerial volcanic deposits
- Analysis and interpretation of the results