{"id":15844,"date":"2015-08-22T05:30:09","date_gmt":"2015-08-22T05:30:09","guid":{"rendered":"http:\/\/blogs.agu.org\/landslideblog\/?p=15844"},"modified":"2015-08-21T16:42:23","modified_gmt":"2015-08-21T16:42:23","slug":"mount-rainier-2015-1","status":"publish","type":"post","link":"https:\/\/blogs.agu.org\/landslideblog\/2015\/08\/22\/mount-rainier-2015-1\/","title":{"rendered":"Mount Rainier debris flows, 13th August 2015"},"content":{"rendered":"
Mount Rainier debris flows<\/h5>\n

The Mount Rainier National Park Facebook page<\/a> has a nice report about a series of debris flows that occurred on the flanks of the volcano, in Washington State, USA on 13th August 2015 (and there is a good press release<\/a> too).\u00a0 These debris flows originated from the South Tahoma Glacier and rumbled down Tahoma Creek, as this Mount Rainier National Park map<\/a> shows:<\/p>\n

\"Mount<\/a>

Mount Rainer National Park<\/p><\/div>\n

.<\/p>\n

The debris flows originated as a series of collapses of ice-rich glacial sediment, triggered by the release of stored water from the glacier.\u00a0 This is a common type of event on the flanks of Mount Rainier – indeed the USGS has a webpage describing them<\/a>. \u00a0 A helicopter overflight<\/a> by Scott Beason of the Mount Rainer National Park identified the source of the flows quite beautifully:-<\/p>\n

\"Mount<\/a>

Scott Beason, Mount Rainier National Park<\/a><\/p><\/div>\n

.<\/p>\n

\"Mount<\/a>

Scott Beason, Mount Rainier National Park<\/p><\/div>\n

.<\/p>\n

There is a stunning album of aerial photographs of this event on the Mount Rainier Flickr Page<\/a>.<\/p>\n

Perhaps the most exciting element of these events though was the capture of them on the local seismic monitoring network.\u00a0 As the Mount Rainier National Park Facebook site<\/a> observes:<\/p>\n

“Looking at seismic data from the Pacific Northwest Seismic Network<\/a>, the vibrations from the debris flow are recorded on seismograms from Rainier station RER, located at Emerald Ridge overlooking Tahoma Creek. The debris flow signal starts at ~9:50 AM PDT. Signals are emergent, pulsatory, and relatively high-frequency\u2014all characteristics of debris flows. There was a period of time from ~9:50 AM through to ~12:45 PM where signals were occurring relatively continuously, with several tens-of-minutes-long higher-amplitude bursts at 10:15-11:10, 11:25-11:50, and 12:30-12:40 that probably correspond to major debris-flow pulses. No debris-flow-like signals showed up overnight.”<\/p><\/blockquote>\n

This is the seismic record:<\/p>\n

\"Mount<\/a>

Mount Rainer National Park<\/a><\/p><\/div>\n

.<\/p>\n

Liveleak has a nice video<\/a> of one of the debris flow pulses passing through:<\/p>\n