The exploration with the submersible suggested the need for remapping the lake floor with modern techniques to provide a bathymetric (depth) map for interpreting the postcaldera geologic history and as a base for further study of the lake itself. Several dives were devoted to exploring the volcanic features on the lake floor and to sampling caldera-wall outcrops. In 19, scientists from Oregon State University, the National Park Service, and the USGS explored parts of the lake floor with a manned submersible, paying special attention to the warm areas identified earlier.
These crater-like structures were probably formed by steam explosions as water began to accumulate within the still-hot debris shortly after the cataclysmic eruption.Ī later USGS party mapped areas where large amounts of heat escaped from the lake floor. Nelson’s study found that beneath the sediment were many depressions located along the caldera collapse ring fractures. In 1979, Nelson returned to the lake as a USGS marine geologist and used acoustic imaging techniques (like making a CAT scan) of the lake floor to discover that as much as 250 feet (75 m) of sediment had accumulated since caldera collapse. Hans Nelson collected dredge samples that showed a variety of post-7,700-year eruptive activity. About the same time, Crater Lake ranger-naturalist C. Contours of these data revealed the principal features on the floor of Crater Lake – the central platform, Merriam Cone, a small lava dome on the east side of Wizard Island, and the Chaski Bay landslide – for the first time. In 1959, the US Coast and Geodetic Survey obtained more than 4,000 echo soundings and provided a more accurate estimate of the maximum depth of Crater Lake 1,932 feet (589 m). It wasn’t until the advent of sonar that the nature of the caldera beneath the lake became clearer.
The National Park Service made additional soundings of this type between 19. With a lead weight and piano wire, Dutton’s party made 168 soundings from a rowboat and reported a maximum depth of 1,996 feet (608m). Clarence Dutton of the USGS led the first expedition to determine thedepthofthelakein1886. Colors range from orange to blue with increasing water depth.įor more than 100 years, scientists have marveled at Crater Lake’s great depth and sought to unravel the mysteries hidden beneath its surface. Geological Survey and the National Park Serviceĭetails of features beneath the surface of Crater Lake constructed using data from the 2000 bathymetry survey. Mount Mazama and Crater Lake: Growth and Destruction of a Cascade Volcano
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