Advisor – Quimper Geological Society

Michael Machette is a practicing earthquake geologist and the owner of Paleo Seis Surveys LLC, a geologic consulting firm that deals with geologic hazards at critical facilities such as nuclear power plants, dams, and pipelines. His projects have included a Trans-Turkey gas pipeline, hazard analyses of nuclear power plants in Arizona, Brazil, Idaho, and Utah. He earned a B.Sc. in Geology from San Jose State University in 1972 and his M.Sc. in Quaternary Geology from the University of Colorado in 1975.

For most of his career he was a geologic mapper and research geologist with the U.S. Geological Survey (1972-2008) in Denver, CO. He was the former chief of the their Quaternary fault and fold database for the USA, as well as Chairman of the World Map of Active Faults for the Western Hemisphere. Over his 36 year career, he worked mainly in the InterMountain West, as well as a dozen countries internationally. He has authored about 150 scientific papers and maps, and given an equal number of oral presentations. His last USGS project dealt with the Quaternary history of the San Luis Basin, and particularly ancient Lake Alamosa.

After retiring to Port Townsend in 2008 he built an earthquake-resistant house in Kala Point, and served as Treasurer and Secretary over a six-year term as Board member of the Jefferson Land Trust, as well as ringleader of their Geology Group, which is now known as the Quimper Geological Society. After the press caught on to the Cascadia subduction zone M9 earthquake and associated tsunami (2015), he organized a workshop on the subject and the following years give about 20 lectures to local community groups on the Quimper Peninsula. The workshop and lectures were attended by a total of about 1,500 persons, which helped broaden the message of Earthquake Preparedness in Jefferson County. Michael continues to be a ringleader for the Quimper Geological Society. (Updated Feb. 2022)

From the Accretion of the Olympics to the Birth of the Cascades: The Eocene Transformation of Washington Geology

About the lecture

Dr. Jeffrey Tepper

Dr. Jeffrey Tepper will show how Port Townsend lies between two mountain belts with very different origins, the oceanic Olympic Mountains to the west and the continental Cascade Range to the east. But despite their contrasting traits, the histories of these two chains are intimately connected. In this talk we will explore how the arrival of the Siletzia terrane about 52 million years ago led to a profound geological transformation of the Pacific Northwest. Over a 10 million year interval in the mid-Eocene (~54-44 Ma), volcanic activity swept across the region from as far east as Montana, extensional stresses triggered faulting and formation of sedimentary basins, the Olympics were established, and volcanism in the Cascades was initiated. All of these phenomena can be linked to the accretion of Siletzia, which caused the Farallon Plate that had been subducting beneath Washington to slow, roll back, and ultimately break off. The evidence of these dramatic events is recorded in rocks we see at the surface as well as in geophysical anomalies deep in the mantle. This event is sponsored by Quimper Geological Society, an Earth Science outreach group of Jefferson Land Trust. For more information about our group and our local/regional geology, visit QuimperGeology.org

About the speaker

Jeff Tepper has been on faculty of the Geology Dept at the University of Puget Sound since 2001. He earned his PhD from UW, where he studied the origins of granite in the North Cascades. At UPS he teaches classes in mineralogy, petrology, geochemistry, GIS, and geomythology. Most of his research projects focus on the magmatic and tectonic history of the Pacific Northwest (including Tamanous Rock), or on the geochemistry of water and sediment from Tacoma-area lakes.