About the Talk

Eruptive History and Hazards of the Mount Baker Volcanic Field

On a clear day in Port Townsend, you can’t help but notice Mount Baker to the northeast, just beyond Bellingham. Just 60 miles away, this spectacular volcano lies restless, its history largely unknown until recently.

 The geologic history of the Mount Baker Volcanic Field is now well documented for the past 3-4 million years. The ice-mantled cone of Mount Baker is but the youngest in a long series of eruptive centers, which includes two calderas (large eruptive cauldrons). The past 10,000 years (the Holocene) has seen a decrease in “constructional” lava flows.

Conversely, “destructional” events, such as flank collapses that evolve into far more hazardous lahars are now recognized as the Holocene norm at Mount Baker. Mount Bakers historical record begins in 1843 and ironically is among the most obscure, despite eye-witnesses reports and newspaper accounts. The reasons for the famous “failed-eruption” of 1975 is the latest example of the historic puzzle; this event provided the backdrop to the modern age of volcano monitoring in the Cascade and Aleutian arcs.

About the Speaker

Dave Tucker is a Research Associate in the Geology Department at Western Washington State University (Bellingham) and Director of the Mount Baker Volcanic Research Center, which is the nucleus for ongoing volcanic research at the mountain. Dave has published (2019) Geology Underfoot in Western Washington. The book features several dozen field trips to exciting geologic sites in our region.

Book – Geology Underfoot in Western Washington (field trip guide)

About the Talk

Mt. Rainier—New Information about the Volcano in Our Backyard

Mount Rainier has been called the most hazardous volcano in the United States. It’s an active volcano with a seismic pulse and hissing fumaroles in its east summit crater; some crater water is at the 86° boiling point for that elevation. Recent research shows that this sleeping giant has erupted for more than half a million years and that it has had more than 40 eruptions since glaciers retreated from the Puget Lowland about 15,000 years ago. It has generated great lahars (huge volcanic debris flows) that buried forested river valleys for tens of kilometers. Some lahars flowed all the way to Puget Sound and, along with later sedimentation, greatly modified the Puget Lowland landscape. The volcano’s glaciers have been retreating in recent years, and as they do, rivers heading on Mount Rainier have been moving sediment quickly downstream, resulting in an annual drumbeat of alluviation in lowland areas. Pat will discuss how geologists are continuing to study and monitor the volcano and the potential impacts of future eruptions.

About the Speaker

Mr. Pringle is Assoc. Professor of Earth Science at Centralia College, Washington. He was with Washington DNR’s Division of Geology from 1990 to 2005 and with the U.S. Geological Survey’s Cascades Volcano Observatory from 1982 to 1990. Pat studies volcanoes, earthquakes, landslides, and debris flows, commonly using radiocarbon and tree-ring analysis to establish the history of past geologic events. He is the author of books on the roadside geology of Mounts St. Helens and Rainier. His Mount Rainier book won “Best Guidebook Award” at the Geological Society of America’s 2009 Annual Meeting.