Thursday, August 13, 2015

Today's Event



Day 304: This is one of my favourite maps. It was published by the USGS in 1973 and is entitled, "Potential Hazards from Future Eruptions of Mount Rainier, Washington" and covers all the possibilities from flood, mudflow, avalanche and/or tephra (airborne volcanic rock debris). The whole of the upper Nisqually Valley lies in the red and orange zones (areas of highest risk). That's why we get a little nervous around here when the earth shakes, or we hear rumblings on the Mountain.

There's a reason I selected this particular section of the map. Tahoma Creek (labelled just above the more obvious "Satulick Mountain") has turned loose a number of small "outburst floods" over the years, including one which wiped out a large section of the Tahoma Creek Trail and portions of the Westside Road. For this and other reasons, the Park decided to close Westside Road three miles in at Dry Creek. The road is still passable, and official vehicles are allowed beyond the closure, although they must be high-clearance rigs in order to navigate a number of rough washouts and a side stream.

Today, there was an "event" in Tahoma Creek. An outburst flood occurred somewhere up-valley, and the first we heard of it was when a report of a mudflow crossing Westside Road came over the radio. The person reporting the event was on the far side, and took the sensible precaution of moving to higher ground, roughly somewhere between the first W in "Mount Wow" and the M in "Satulick Mountain." She reported a noise like "a couple of helicopters" growing louder and louder as the river swelled and blustered its way over rocks and through forest. By the time the rumbling had subsided, rangers and geologists were on the way to investigate, and to try to locate any hikers who might have been in the area at the time.

I did not find out until a few hours later that the person reporting the event was our intern, Yonit. When she showed up at the office, she was rather visibly shaken but excited to relate the circumstances to us. Later, she showed photos she had taken with her phone of the water and mud breaching the road, and how it had undermined the pavement. She had been escorted to safety by the rangers even as the geologists went up in a helicopter to study the site.

When Kevin and I drove out tonight, Tahoma Creek was still flowing with some ferocity, and as thick as whipping cream with silt and mud. Westside Road has been gated off at the entrance. As outburst floods go, this was minor in terms of resource damage, but as temperatures remain in the 80s and glacial ice melts, the potential is there for more or larger events to occur. The red zone is real. I'm in it, and with full realization of the fact.

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