Mount Shasta Debris Flow Hazards Research Presented. Geologist Michelle Roberts of SHN Consulting Engineers & Geologists, Inc. presented her research on lahar hazards at the 117th annual meeting of the Geological Society of America.  The meeting was held October 16 – 19, 2005, at the Salt Palace Convention Center in Salt Lake City, Utah.  Approximately 6,200 geoscientists from across the country attended.

A lahar (a mixture of rock, mud, water, and debris that flows down from a volcano) can be extremely dangerous depending on its size and origin.  Roberts began research on lahars at Mount Shasta for a master’s thesis from Humboldt State University and teamed up with Steven McClung of Oregon State University to present a poster entitled, “Factors Affecting the Degree of Hazard Posed by Lahars at Mount Shasta, California.”

According to Roberts, lahar frequency at Mount Shasta varies with its location on the mountain, resulting in different degrees of hazard for communities around the volcano.  Lahars may form on Mount Shasta from at least three processes: rapid glacial melting, volcanic eruptions, and debris avalanches.  Lahars originating in glaciated drainages, such as Mud Creek and Whitney Creek are far more frequent than those caused by eruption (eruptions on Mt. Shasta occur about every 600 years).   “The town of McCloud faces a greater risk of lahar inundation due to its proximity to Mud Creek, and in the 1990’s, Whitney Creek, on the north side of Mount Shasta, produced lahars that damaged a major highway.  Lahars originating from debris avalanches have only occurred once in Mount Shasta's 500,000+ year-old history. While lahars from such an event would be extensive and potentially devastating, the infrequency of such an event suggests these lahars as a very low hazard."

“Lahar inundation can also be approximated using DEM (Digital Elevation Modeling) based software.  Recently, lahar inundation modeling has been performed for the Mud Creek, Whitney Creek, and Big Canyon Creek drainages.  Resulting maps may be used as broad guidelines for hazard delineation, as the modeling still cannot predict exact inundation paths.”

“Our geoscientists are always studying to find out more about the geology of our region and how to use that knowledge to better help the community, “says Tom Stephens, Geosciences Director and Principal Geologist at SHN.  “Michelle’s research on lahars is exciting and informative.  It may ultimately save lives, and presenting this research at GSA is an excellent way to disseminate this important information.”

SHN’s Geosciences Division specializes in providing geotechnical engineering, engineering, geologic, and hydrogeologic services to communities throughout northern California and southern Oregon.  SHN has provided comprehensive and creative professional services in the fields of civil engineering, geosciences, environmental and hazardous materials, planning and permitting, and surveying to clients throughout northern California and southern Oregon for more than 26 years.   Starting as a small office in Eureka in 1979, SHN now has additional offices in Redding, Willits, and Yreka, California; and Coos Bay, Oregon. 

For more information, please call SHN at 707-441-8855.