March 24, 2013
by John Vidale
It has mostly been seismically quiet recently, although last night and this morning a swarm has been active in southern Oregon. With four events above M2 and one above M3, it is notable. On a map, little detail is resolvable because our seismic network is thin in this part of the Pacific Northwest.
This plot shows the earthquakes in the region since the 1960s, there is clearly a concentration just west of a slight bump of a mountain, with no name that we can identify. One guess is that the bump is an exhumed throat of an ancient volcano. Note Mount McLoughlin in the lower right for reference. We cannot resolve details of the earthquake pattern, nor even the depth, except to say the quakes are in the upper 20km, due to the fact that the nearest station is 35 km away.
The plot of cumulative numbers of earthquakes shows the 9 so far in the latest sequence, and a greater number in 2011, and lesser swarms in 2008 and last year, with a few even more minor episodes.
The plot of earthquake magnitude vs time shows events only exceeded M2 this year and in 2008, and the event event last night of M3.1 is the largest.
So I've described the earthquakes, but what is driving them remains a mystery. We scientists now have more tools at our disposal, and could look at InSAR maps to search for surface deformation, do precise locations to better identify seismicity patterns, and rush out with portable instruments for a closer look.
But for a small swarm in a relatively sparsely populated region, we'll probably just do the usual, keep an eye on it.
- Three Cascadia ETS events in past month??
- Is Mount St. Helens seismicity increasing?
- Warm weather triggers snow avalanches at St. Helens
- Seismic recordings of a gas explosion in North Bend, WA
- Seismic signals generated by the March 22nd Oso Landslide
- Legacy web site content returns
- Ice avalanches on Cascade volcanoes
- A New View On What's Shaking on the Cascade Volcanoes
- Seismic Spectrograms - A new way to look at wiggles
- The final football game analysis
- September (1)
- July (1)
- May (1)
- April (1)
- March (2)
- February (3)
- January (4)
- October (1)
- September (1)
- August (1)
- June (1)
- April (3)
- March (4)
- February (1)
- January (2)
- December (1)
- November (2)
- October (3)
- September (1)
- August (3)
- July (2)
- June (4)
- May (4)
- April (2)
- The wech-o-meter takes over all of Cascadia
- Keystone Cops: Italy prosecutes seismologists for failure to predict deadly quake
- UFOs in eastern Washington? No, rather UTEs (Unidentified Terrestrial Events)
- New Sodo Seattle Liquefaction Array Installed
- Why we should constantly watch the deformation of the seafloor
- Mystery chirp near Newberry Volcano
- Planting seismographs causes earthquakes? or maybe ice-quakes?
- Tunneling rumbles south under Capitol Hill
- 15 years of mostly silent magma inflation near Three Sisters, Oregon
- Mount Hood earthquake swarm of Feb 23, 2012
- Web glitches: duplicate (and even triplicate!) earthquakes
- How earthquake magnitude scales work
- Mine blast masquerades as volcanic tremor
- The Spokane Swarm about 10 years ago
- Another hum around Mount St. Helens
- Slow slip: A new kind of earthquake under our feet
- PNSN and social media
- 3am M3.4 earthquake in St. Helens Seismic Zone
- The wrong kind of volcano noise
- Fast chatter on Rainier an hour ago
- Can slush-mageddon trigger earthquakes?
- Rainier Repeating Earthquakes Update and Comparison with Weather Patterns
- 22-minutes drumbeat icequakes(?)
- Mount Rainier popping away
- Repeating Earthquakes on Mount Rainier - are glaciers the culprit?
- Debunking another SEC football myth by the PAC-12
- One year ago, Seattle Seahawks 12th Man Earthquake
- The odds this year of a megaquake on the Pacific Northwest coast
- Is the plague of great earthquakes this decade a sign of increased danger?
- Nile Valley landslide talks to PNSN seismologists
- Good vs evil in central US earthquake hazard analysis
- Why does a volcano scream?
- Predicting big quakes from patterns of little ones
- 1-hour warning for Japanese M9 earthquake?
- Sound Transit train under Interlaken keeps a rollin'
- Invisible changes under the hood at the PNSN
- Sound Transit Tunneling Noise
- "Visionary" toads
- Earthquake early warning in the PNW
- November (1)
- December (13)