OSO — Researchers who have spent the past several weeks at the site of the Oso mudslide are starting to release some preliminary data of their findings.

While the initial priorities for responding to the March 22 slide were rescue and recovery operations, and then reopening Highway 530, several teams of scientists have begun the long process of picking up various threads and tracing them back to discover why the slide behaved the way it did.

Snohomish County has taken a lead role in coordinating access to the slide site, and is convening a task force to explore causes and effects, although the planning is still in its very early stages.

Two independent teams of researchers have visited the site.

One, called GEER (for Geotechnical Extreme Events Reconaissance), is a team of earth and engineering scientists whose mandate in Oso was to gather as much raw data and evidence, as quickly as possible, before it was obscured or erased by natural processes.

GEER would then make its findings publicly available and free for the entire scientific community to use and incorporate into future studies.

This particular team, led by Joseph Wartman, a professor of civil and environmental engineering at the University of Washington, visited the site in late May and may be releasing a report within the next few weeks.

GEER’s reports are usually posted on its website, geer association.org.

Another team came from the University of Illinois at Urbana-Champaign’s Department of Civil and Environmental Engineering.

That team, led by the university’s Timothy Stark, a professor of civil and environmental engineering, posted a preliminary report on its initial observations on the university’s website.

One key point the Illinois team discovered was that it appeared that the runout of the slide splashed quite high on tree trunks on the edges of the slide zone, which suggested the slide behaved more like a fluid than as consolidated soil.

The Illinois team is also doing lab work on soil samples taken from the slide zone, to determine the history of geologic stresses that it experienced and shear strengths of different stratigraphic layers.

Ultimately, Stark’s team believes that the work will lead to a greater understanding of the causes, behavior and impact of the deadliest disaster in Snohomish County’s history.

Chris Winters: 425-374-4165; cwinters@heraldnet.com.