Lacustrine Records of Environmental Change and Geologic Risk From Nicaragua

Collaborative Effort with:

Robert Dull, Department of Geography, Texas A&M University

Students Involved:

Nathan Stansell, University of Pittsburgh, nas12@pitt.edu

M. Roman-Lacayo, Department of Anthropology, University of Pittsburgh

Images from Nicaragua

Project Summary

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.

Current paleoenvironmental records from Central America are limited in spatial and temporal resolution. Our multi-proxy analysis of lake sediment cores including stable isotope, pollen, paleomagnetism, physical analyses, and Geographic Information Systems (GIS) will provide the first high-resolution reconstruction of paleoenvironmental change and geologic risk from Nicaragua.

A preliminary field season took place during the summer of 2003. A series of lakes were targeted and limnological data were collected from Lagunas Apoyo, Nejapa, Moyua, Verde, and Blanca. These data include Depth, Temperature, Dissolved Oxygen, Conductivity, and pH. Sediment cores were taken from each lake and transported to the University of Pittsburgh cold storage facility for analytical work.

Two sites immediately south of the Mombacho volcano, Laguna Verde (11.762&Mac251;N, 85.964W) and Laguna Blanca (11.766&Mac251;N, 85.959W) overly the most recent prehistoric lahar event, currently dated between ~ 1000 and 25,000 yr BP (van Wyk de Vries and Francis (1997), Sussman (1980)). Lake sediment cores from both lakes record the lahar event and subsequent watershed response. Above the lahar deposit, a core from Laguna Verde contains 1.5 meters of laminated sediment. A 6-meter core from nearby Laguna Blanca records both gradual and abrupt vegetation change in the watershed. AMS 14C dated charcoal from Laguna Verde dates the transition from lahar sediments to lake sediments at 1417 BP. AMS 14C dated charcoal from Laguna Blanca dates the transition at 1271 BP. These dates therefore provide a minimum age for the most recent prehistoric Mombacho lahar event

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