Please enable JavaScript to use all features of this website. January 2018 Oregon Tremor Event Update
Pacific Northwest Seismic Network

January 2018 Oregon Tremor Event Update

January 2018 Oregon Tremor Event Update

Looks like it’s over!

Back in December tremor picked up in central Oregon around the 5th of the month. Since 12/27/17 tremor events have decreased in the Portland and Medford area and appeared to die out by January 7th.

Below is the total tremor profile for Oregon with dark blue signifying the earliest tremor events and dark red the latest. Tremor lasted for 33 days, about a week shy of the previous tremor which began in January of 2016 and continued until March of that year.

Map of the West Coast of Northern California, Oregon, and Washington. Bound north to south by the Portland, Oregon, to Crescent City, California, and East to West by Klamath Falls and the Pacific Ocean. The map is titled "December 5 to January 7" and has the Google logo in the left bottom corner. On the map there is long strip of area outlined that follows closely all the way up the coast, but does not extend completely to the ocean and ends east at Eugene. There is a dense area of red event dots over Canyonville that radiate out north to south and the colors of the dots chromatically change from red to blue as they do so. There is also a dense area of red dots just northwest of Portland, which radiate south and chromatically change to blue all the way util they reach Eugene.

The wech-o-meter shows that tremor for central Oregon showed a strong trend right at the beginning and peaked around December 10th before halting on the 27th. Southern Oregon peaked in the days leading up to the 24th and resurged around the 1st before it stopped at the 7th. Northern Oregon, had some variability throughout the run peaking early, again around the 24th and just after the first of the year.

Wech-o-Meter

A diagram captioned at the bottom as "Applet and tremor catalog created/maintained by Aaron Wech. Please send questions/comments to awech@usgs.gov." The diagram spans over the years 2009 to 2018 and has the range of 0 hours to 20 hours. There are three lines that spike and trough throughout the years and biggest spike being the pink line in the year 2013 reaching 20 hours.

Snapshots of progression :

Comparison to the Previous ETS

There were some similarities and differences between the 2016 and 2018 Oregon event. Both events stayed along strike and followed the previous tremor paths. Both were over a month long, and both were about 22 months apart. Interesting differences were that this year’s ETS started in central Oregon and then split into opposite directions. The density of plots for this year was concentrated more in southern Oregon. In 2016 density was noted mostly west of Portland and Salem.

A Persistent “Gap”

2015 to 2018

We’ve noticed a gap that occurred south of Eugene during the 2018 ETS event and one also to the north of Roseburg in 2016. The last time that area was filled in was in June of 2015. Here we see a gap northwest of Medford. It will be interesting to see if this gap continues to show up during the next Oregon ETS.

But, wait, there’s more!

Could southern Washington be experiencing another ETS event or is this just the continuation of Oregon?

Map of the West Coast of Oregon, Washington, and British Columbia. Bound north to south by the south of Vancouver Island, B.C., to Newport Oregon, and East to West by Mount Hood and the Pacific Ocean. The map is titled "January 20 to January 30" and has to Google logo in the left bottom corner. On the map there is long strip of area outlined that follows closely with the coast, but does not extend completely to the water and ends east Tacoma. Over the South Puget Sound region from Olympia to the Columbia river there is a dense cluster of event dots with the dots closest to Olympia area being red and the ones closest to the Columbia river being blue.

We’ll be keeping an eye on this one and do some more deep diving next time!

Here are some previous blogs to that highlight past ETS events in Oregon and Cascadia:

https://pnsn.org/blog/2017/12/27/december-2017-oregon-tremor-event-update

https://pnsn.org/blog/2017/12/15/december-2017-oregon-tremor-event

https://pnsn.org/tremor/tremor-log/ets-event-of-winter-201516

https://pnsn.org/blog/2016/02/06/back-to-back-ets-events-maybe

https://pnsn.org/blog/2013/03/08/deep-tremor-over-much-of-cascadia