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Volcanoes and Their Products
Published in Dexter Perkins, Kevin R. Henke, Adam C. Simon, Lance D. Yarbrough, Earth Materials, 2019
Dexter Perkins, Kevin R. Henke, Adam C. Simon, Lance D. Yarbrough
Figure 7.18 shows picturesque Crater Lake, 20.6 square miles in size, in southern Oregon. The lake is a perfect example of a small caldera. Lake waters come only from snowmelt and rain and today occupy a caldera that formed about 7700 years ago when Mt. Mazama, a Cascade Range volcano, erupted and the ground subsided after 50 cubic kilometers of felsic magma was expelled. Mt. Mazama’s eruptive history, however, extends back at least 400,000 years, and the volcano is still considered active today. Within a few hundred years after the last major eruption, smaller eruptions created Wizard Island (shown in this photograph) and a few other small cones in the caldera. Crater Lake is the deepest lake in the United States (594 meters; 1949 feet) and ranks in the top 10 worldwide.
Igneous activity and landforms
Published in Richard J. Chorley, Stanley A. Schumm, David E. Sugden, Geomorphology, 2019
Richard J. Chorley, Stanley A. Schumm, David E. Sugden
Five examples of such calderas will serve to show their range of characteristics. Monte Somma, Vesuvius, with a diameter of 3 km and formed by the eruption of 79 AD has already been depicted in Figure 6.21. Crater Lake, Oregon, was formed by the eruption of a 3600-m cone in about 6000 BP, leaving a caldera of 10 km diameter now partially filled by a lake some 600 m deep in places above the level of which is a 150–600-m high rim and a more recent circular volcanic cone of Wizard Island rising 230 m above lake level (Figure 6.23E). Three well-documented calderas were formed in the nineteenth century: the Krakatoa caldera of 6 km diameter was formed from the 1883 eruption of an 1800-m-high Pleistocene volcanic cone; the Coseguina caldera, Nicaragua, of 4 km diameter and 450–600 m deep was formed by the collapse of about one-half of the mountain in 1835; and the Bandai San caldera in Japan was formed by a 400-m subsidence of 2.5 km diameter in 1888 accompanied by violent explosions, but no solid or liquid products.
Why Are We Going Green?
Published in Eric Koester, Green Entrepreneur Handbook, 2016
With populations moving from the countryside into urban centers and more of America’s great national resources being commercialized or exploited, certain leaders began to take steps to slow urbanization. Many point to president Theodore Roosevelt’s love of nature and the outdoors as a key point in the environmental movement. In 1902, Roosevelt established the first national park at Crater Lake, Oregon. During his presidency, he created four additional national parks and 51 wildlife refuges, passed the Antiquities Act (which led to the creation of 18 national monuments), and created the National Park Service. In addition, the pioneers of the environmental movement in the United States include John Muir (founder of the Sierra Club), Henry David Thoreau (author of Main Woods), and George Perkins Marsh.
Whakaari/White Island: a review of New Zealand’s most active volcano
Published in New Zealand Journal of Geology and Geophysics, 2021
Geoff Kilgour, Ben Kennedy, Bradley Scott, Bruce Christenson, Arthur Jolly, Cameron Asher, Michael Rosenberg, Kate Saunders
The first remotely operated digital camera was installed in October 2001 at the Factory site (CVWF). Since then, the camera network has been expanded to North Rim (WINR) in April 2013 and West Rim (WIWR) in October 2016 and one from Whakatane (February 2006) (Figure 3). This network has proved vital for assessing changes in the crater lake basin, including qualitative assessments of active fumarole outputs. They have also been informative during eruptions, such as calculating the flow velocity of pyroclastic density currents and plume rise rates (Kilgour et al. 2019) during the April 2016 and December 2019 eruptions (unpublished).
Glaciers and glaciation of North Island, New Zealand
Published in New Zealand Journal of Geology and Geophysics, 2021
Shaun R. Eaves, Martin S. Brook
Whangaehu Glacier is sourced from the southern end of Summit Plateau, flowing eastwards between Dome ridge and Cathedral Rocks, and the debris-covered terminus is situated at c. 2100 m asl (Figure 3). Whangaehu River catchment is the main drainage pathway for outflow from Crater Lake at present, although at its source most flow is routed down a tributary catchment immediately south of Whangaehu Glacier. Volcanically induced displacements of Crater Lake water are often routed over the Whangaehu Glacier, and may be a considerable source of the extensive surface debris visible at present. Krenek (1959) documented the glacier terminus position for 1941, 1954, and 1955, with the 1955 terminus position similar to that of O’Shea (1959). Crevassing of the Summit Plateau region between Dome and Cathedral Peaks (highlighted by O'Shea 1959), suggests the Summit Plateau glacier was the source for Whangaehu Glacier. O'Shea’s (1959) map also indicates a thin corridor of ice connecting Whangaehu Glacier to the Crater Basin Glacier via the lake outlet gorge, although this may have been snow. Keys (1988) reported that Whangaehu Glacier was the only glacier on the volcano to still be fed by ice flow from Summit Plateau, although it was observed that the continuing thinning of the plateau was reducing this input. Surface velocity measurements on the glacier by Paulin (2008) showed that the glacier was flowing at an average of 30 m yr−1. Mass balance measurements and end-of-summer snowline observations on Whangaehu Glacier showed complex and highly variable interannual patterns, likely driven by wind redistribution of snow and variations in ablation season temperatures (Paulin 2008). Currently, Whangaehu Glacier is the largest glacier on Mt Ruapehu, and was measured by Keys (1988) as 0.76 km2. At the end of the 2016 ablation season, this area was ∼0.60 km2 (−21% relative to 1988; Table 2), with the surface almost entirely debris covered (Figure 7B).