ETS Event of Fall 2020
Blog for ETS of Fall 2020
Deep Tremor News: Fall - Winter 2020
This BLOG-like page is being generated in a form similar to previous ETS ones to document and provide information on a Northern Washington ETS that should start sometime between Oct. and Dec, 2020. There are no special experiments in the field for this ETS. We will be tracking and reporting on this ETS using data only from the real-time regional networks (UW, UO, CN, PB, CA) and/or information reported to us by others.
Produced by Steve Malone, PNSN Professor Emeritus
Information will be posted on this page (latest at the bottom) and references to figures from time to time.
NEWS (latest is at the bottom):
Sep. 16, 2020 - In anticipation of a routine ETS (or pair of them) in the northern Washington (NWA) - southern Vancouver Island (SVI) section of Cascadia I am starting this blog a bit early. Of course, how this next ETS will start and if it will be one regular event (as typical over the past 15 years) or come as a pair as it (they) did last year is unknown at this point. If one looks at the details of the 2019 - summer ETS one sees that it really was two smaller ETS events separated by over two months. Thus we really don't know when the typical repeat time of ~14 months clock should start. The recent burst of activity in Southern Vancouver Island seems to be just that, a burst of a few days and not strong or long enough to be an ETS. The next ETS in this area could start as soon as early October or it might not be until January, 2021; or there could be again two separate ETS events separated by months. ETS sequences are far from understood so any number of things are possible. Stay tuned.
By the way, we have received inquiries from several people about reports of an unprecedented amount of tremor taking place recently. It is not clear to us why some think there is significantly unusual tremor activity taking place. There is not. We recommend before folks get all excited about what our daily tremor page shows that one review the data and reports for the past 15+ years. Lots of details can be found in the individual reports listed at the Tremor Overview page and a very good summary of overall tremor patterns was written by Aaron Wech, an expert in such events not only in Cascadia but also elsewhere in the world called A Perspective on Tremor Activity. Dr. Wech recently allowed how we should keep in mind the break or change in the catalog that occurred in February 2018 when he upgraded the monitoring system. Changes in the clustering/detection algorithm then result in a ~50% increase in detected epicenters, so comparing raw number of detections today vs before 2018 isn't apples to apples. Having tremor take place up and down Cascadia at the same time has occurred several times in the past 15 years and thus is not unprecedented. A report on an example can be found at Deep Tremor over much of Cascadia from back in 2013.