LACUSTRINE RECORDS OF PALEOENVIRONMENTAL CHANGE AND GEOLOGIC RISK FROM NICARAGUA

Archaeological and paleoenvironmental evidence has linked events such as the collapse of prehistoric and historic societies to abrupt environmental change. Archaeological research in the Masaya region of Nicaragua identified dramatic population growth during the late Holocene, punctuated by several periods of abrupt cultural collapse. Nicaragua sustained numerous geologically and climatologically driven environmental hazards during the late Holocene, including an overall increased aridity, multiple ENSO events, earthquakes, hurricanes, and volcanic hazards. Our multi-proxy analysis of lake sediment cores including stable isotope, pollen, paleomagnetic, and physical analyses will provide the first high-resolution reconstruction of paleoenvironmental change and geologic risk in Nicaragua. In particular, sites immediately south of the Mombacho volcano, Lagunas Verde and Blanca are superimposed on the most recent lahar event, currently dated between ~ 430 and 25,000 yr BP. Above the landslide deposit, a core from Laguna Verde contains 1.5 meters of finely laminated, carbonaceous sediment. A 6-meter core from nearby Laguna Blanca contains no carbonates below the first meter of sediment, and records both gradual and abrupt vegetation change in the watershed. AMS ¹⁴C dated charcoal, currently being analyzed from Lagunas Verde and Blanca, provide a minimum age for the most recent Mombacho landslide, drastically improving the chronology for the latest volcanic induced hazard.