Confluence Retirement

In an effort to consolidate USGS hosted Wikis, the myUSGS Confluence service is targeted for retirement on January 28, 2022. The official USGS Wiki and collaboration space is now SharePoint. Please migrate existing spaces and content to the SharePoint platform and remove it from Confluence at your earliest convenience. If you need any additional information or have any concerns about this change, please contact myusgs@usgs.gov. Thank you for your prompt attention to this matter.

Versions Compared

Key

  • This line was added.
  • This line was removed.
  • Formatting was changed.

...

The 2018 Corvallis workshop on building a new Cascadia 3D seismic model identified a need for review papers highlighting existing data and interpretations.  In this map Tom Brocher has summarized the locations of 34 individual controlled-source wide-angle seismic imaging experiments dating to the 1960s.  Together, they provide 40 million independent ray paths sampling the subsurface. There are important gaps in these surveys in northern and southern Oregon. The Corvallis workshop report is attached (click on paperclip at the top of the page).

View file
nameCascadia Wide Angle Seismic (1).pdf
height250


View file
nameBrocher 1873 Crescent MMI.pdf
height250
1873 Crescent City earthquake:The location of this earthquake is very uncertain:  could it be a megathrust event?  Tom Brocher has been working in newspaper archives to uncover new accounts of the earthquake to update the ShakeMap for this earthquake.  There are few felt reports of the earthquake south of the southern edge of the Gorda slab and really no reports of aftershocks.  Tom thinks the best interpretation of these observations is that the earthquake occurred within the slab underneath the Oregon-Washington border.  Such inslab earthquakes produce few aftershocks and the slab provides an efficient waveguide for seismic waves.




Lydia Staisch  -  Coastal uplift ratesLydia Staisch - Staisch described her work on coastal uplift rates in SW southwest washington.

Janet Watt or Maureen Walton (10-15 min) - CMG activitiesdescribed CMG past and planned activities, as follows:

  • USGS, in collaboration with NOAA, collected 22 days of high-resolution multibeam, backscatter, and water column data in July-August 2018 aboard the NOAA Ship Rainier. New data show fault structures and seeps on the seabed.
  • CMG recently (Oct 2018) completed the first of several geophysical cruises aimed to obtain comprehensive 2D high-resolution multi-channel seismic, Chirp, and magnetometer data along the Cascadia margin. The 10-day October 2018 cruise took place aboard the R/V Coral Sea as a collaboration with Humboldt State University.
  • Later in FY19, CMG is slated to complete 3 additional 10-day high-resolution geophysical surveys in Cascadia using UW's R/V Rachel Carson. These surveys will expand 2D geophysical coverage along the margin and examine turbidity flows in Astoria Canyon.
  • Into FY20, CMG is looking forward to involvement with the 2020 R/V Langseth survey led by Suzanne Carbotte at Lamont - USGS will aim to add OBS instruments to the survey to acquire long-offset reflection and refraction data. 
  • In FY20-FY21, USGS will pursue collaborations to acquire 3D P-cable high-resolution seismic data in key area(s) and groundtruthing of geophysical surveys via piston coring and other sampling.
  • Slides are attached (see paperclip at the top of the page).

Erin Wirth Erin updated us everyone on the M9 project, noting there are 2 recently published papers on M9 ground motion simulations (see Frankel et al., Wirth et al.). The simulation output is available on DesignSafe. The City of Seattle has revised design recommendations for tall buildings in the Seattle basin based on their results (see OFR report).  The M9 Project Final Workshop will be Tuesday, March 12, 2019 @ UW; contact Erin if interested in attending.

 

Listeners - Bruce Jaffe (late?)

 

Unable to attend - Stephanie Ross, Bill Schulz and Nathan Miller, others?