2022-11-19 Karl Wegmann, Recent advances in understanding the Lake Crescent fault system

Earthquakes, Rock Avalanches, Displacement Waves, and Turbidites: The Amazing Holocene Sedimentary Record from Lake Crescent, Clallam County, Washington


The Lake Creek–Boundary Creek fault zone lies below Lake Crescent, a deep, glacially carved lake on the north side of the Olympic Peninsula, west of Port Angeles. This fault zone includes a system of structures that reveals at least 56 kilometers (35 miles) of late Pleistocene to Holocene surface rupture. New data from the sediment cores taken from the lake’s bottom document four ruptures along the fault zone. Those seismic events triggered several large rockslides along the slopes adjacent to ancestral Lake Crescent that split the lake into two:  Lake Crescent and Lake Sutherlund. After this separation, each lake established its own drainage system to the Strait of Juan de Fuca. Over time, the salmonids in each lake have developed genetic differences that now make them distinct new species.

Karl explained the tools and processes he and his colleagues used to understand the past ~7200 years of lake history by examining sediment cores. He also shared their thoughts on the calculated risk of a ~Mw 6.5-7 earthquake in the next 100 years… and the outcome of salmon speciation.

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The Speaker

Karl Wegmann is a local guy! Well, he grew up on the north side of the Olympic Peninsula, where his parents still hike the trails. He received his Ph.D. (2008) Earth and Environmental Science, Lehigh University, Bethlehem, PA; and M.S. (1999) Earth and Planetary Sciences, University of New Mexico, Albuquerque, NM; starting college career with a B.A. (1996) Geology, Whitman College, Walla Walla, WA; and best of all he graduated from Port Angeles High School (1992).

Karl currently is an Associate Professor of Geology at the Department of Marine, Earth, and Atmospheric Sciences, North Carolina State University (2015-present) and is Faculty Fellow – Center for Geospatial Analytics there as well (2017 – present).

His previous work as a geologist, no doubt, helps his students become geologists with practical experiences. He worked as a geologist with Washington State Geological Survey (1999-2004). He has more than 70 research publications, including peer-reviewed journal articles, geologic maps, and landslide hazard assessments. Karl is fully engaged in academia and is Primary Mentor/Advisor for 8 Ph.D. and 7 M.S. graduate students at N.C. State who have conducted research on the Olympic Peninsula of Washington State, Colorado, New Mexico, North Carolina, Oregon, Greece, Mongolia, and Mars; he is also co-creator of the HazMapper.org platform for global, open-source, and publicly available natural hazard detections via cloud computing. And to top life off, Karl has just finished the post of the 2021-2022 Chair of the Quaternary Geology and Geomorphology Division of the Geological Society of America.