Are great Cascadia earthquakes recorded in the sedimentary records from small forearc lakes?

Here we investigate sedimentary records from four small inland lakes located in the southern Cascadia forearc region for evidence of earthquakes. Three of these lakes are in the Klamath Mountains near the Oregon–California border, and one is in the central Oregon Coast range. The sedimentary sequences recovered from these lakes are composed of normal lake sediment interbedded with disturbance event layers. The thickest of these layers are graded, and appear to be turbidites or linked debrites (turbidites with a basal debris-flow deposit), suggesting rapid deposition. Variations in particle size and organic content of these layers are reflected in the density and magnetic susceptibility data. The frequency and timing of these events, based on radiocarbon ages from detrital organics, is similar to the offshore seismogenic turbidite record from trench and slope basin cores along the Cascadia margin. Stratigraphic correlation of these anomalous deposits based on radiocarbon ages, down-core density, and magnetic susceptibility data between lake and offshore records suggest synchronous triggering. The areal extent and multiple depositional environments over which these events appear to correlate suggest that these deposits were most likely caused by shaking during great Cascadia earthquakes.This is the publisher’s final pdf. The published article is copyrighted by the author(s) and published by Copernicus Publications on behalf of the European Geosciences Union. The published article can be found at: http://www.natural-hazards-and-earth-system-sciences.net/

Inventory and characterization of wetland habitat on the Winnebago upper pool lakes, Wisconsin, USA: An integrated multimedia-gis approach

An integrated, multimedia-geographic information system (GIS) approach to inventorying and characterizing thirty-nine wetland sites identified on the Winnebago Upper Pool Lakes in Wisconsin, USA was developed. Available black-and-white aerial photographs recorded in 1937, 1957, and 1981 and color digital orthophotos of 2000 were employed as primary data sources to develop a spatio-temporal GIS database using a combination of digital image processing, GIS, Global Positioning System (GPS), and field survey techniques. Ten representative sites were selected to investigate the physical, chemical, and biological characteristics of the wetland habitat in the study area further. Multimedia information as text, graphics, ground photogrpaphs, and digital video was then developed to highlight the ecosystem function and structure of those representative wetlands. A computer-based interactive multimedia system, consisting of a graphical user interface and a GIS application module, was constructed to allow easy access to both the spatial data sets and the multimedia information. Given the increased concern over environmental preservation, expansion of urban development, and agricultural land use, it is anticipated that the database will prove valuable for a series of management tasks. The integrated approach provides an innovative way for integrating, analyzing, and presenting wetland information, thus enabling truly interactive collaborations among resource managers, policy makers, researchers, and stakeholders

Are great Cascadia earthquakes recorded in the sedimentary records from small forearc lakes?

Here we investigate sedimentary records from four small inland lakes located in the southern Cascadia forearc region for evidence of earthquakes. Three of these lakes are in the Klamath Mountains near the Oregon–California border, and one is in the central Oregon Coast range. The sedimentary sequences recovered from these lakes are composed of normal lake sediment interbedded with disturbance event layers. The thickest of these layers are graded, and appear to be turbidites or linked debrites (turbidites with a basal debris-flow deposit), suggesting rapid deposition. Variations in particle size and organic content of these layers are reflected in the density and magnetic susceptibility data. The frequency and timing of these events, based on radiocarbon ages from detrital organics, is similar to the offshore seismogenic turbidite record from trench and slope basin cores along the Cascadia margin. Stratigraphic correlation of these anomalous deposits based on radiocarbon ages, down-core density, and magnetic susceptibility data between lake and offshore records suggest synchronous triggering. The areal extent and multiple depositional environments over which these events appear to correlate suggest that these deposits were most likely caused by shaking during great Cascadia earthquakes