August 29, 2016
1:45 pm
by: HBVAdmin

HBI Meeting 2016.08.29

We presented a summary of our results from Phase I of our science plan funded by the Landscape Conservation Cooperative at the Humboldt Bay Initiative meeting. The meeting was held at the Humboldt County Agriculture Center on south Broadway in Eureka.

This page has some supporting material from this presentation, including the digital presentation file. Dr. Jason R. Patton made the presentation with additional support from Jeff Anderson and Todd Williams.

Jay is available at: jayp at cascadiageo.org, quakejay at gmail.com, or Jason.Patton at humboldt.edu

    This is the digital presentation

  • Here is the digital presentation (30 MB pptx).

    This is the digital presentation prepared by Jeff Anderson.

  • Here is the supplemental documentation describing the tide gage analysis. (1.2 MB pdf)

    This is a video of the presentation (aka the Webinar)

  • There are 2 versions, an embedded mp4 file and an embedded yt video. For offline viewing, download the mp4 file. This video is in 1080 HD format.
  • Here is a link to a downloadable video file embedded below (600 MB mp4).
  • Here is a link to the yt video embedded below.

    Here are some sources of information about the Cascadia subduction zone

  • For the 315th anniversary of the most recent full rupture CSZ earthquake I put together a summary of our state of knowledge about the CSZ and that 1700 A.D. Jan. 26 earthquake. 2015.01.26
  • The USGS (and others) put together an educational video about the CSZ. I post this video and other supporting information online here: 2015.10.08

Here is a map of the Cascadia subduction zone (modified from Nelson et al., 2004; Chaytor et al., 2004). Dr. Patton discussed this in his talk and also on this page. The Juan de Fuca and Gorda plates subduct northeastwardly beneath the North America plate at rates ranging from 29- to 45-mm/yr. Sites where evidence of past earthquakes (paleoseismology) are denoted by white dots. Where there is also evidence for past CSZ tsunami, there are black dots. These paleoseismology sites are labeled (e.g. Humboldt Bay). Some submarine paleoseismology core sites are also shown as grey dots. The two main spreading ridges are not labeled, but the northern one is the Juan de Fuca ridge (where oceanic crust is formed for the Juan de Fuca plate) and the southern one is the Gorda rise (where the oceanic crust is formed for the Gorda plate).


Here is a version of the CSZ cross section alone (Plafker, 1972). This shows two parts of the earthquake cycle: the interseismic part (between earthquakes) and the coseismic part (during earthquakes). Regions that experience uplift during the interseismic period tend to experience subsidence during the coseismic period.


This figure shows how a subduction zone deforms between (interseismic) and during (coseismic) earthquakes. We also can see how a subduction zone generates a tsunami. Atwater et al., 2005.

Here is an animation produced by the folks at Cal Tech following the 2004 Sumatra-Andaman subduction zone earthquake. I have several posts about that earthquake here and here. One may learn more about this animation, as well as download this animation here.

This figure shows the regions that participate in this interseismic and coseismic deformation at Cascadia. Atwater et al., 2005. Black dots on the map show sites where evidence for coseismic subsidence has been found in coastal marshes, lakes, and estuaries.

Here is a map showing a number of data sets. Seismicity is plotted versus depth (NCEDC). Tremor is plotted (Pacific Northwest Seismic Network). Vertical Deformation rates are plotted (unpublished). Slab depth contours (km) are plotted (McCrory et al., 2006). Fault locking zones are plotted (Wang et al., 2003; Burgette et al., 2009). Bob McPherson (Humboldt State University, Department of Geology) is currently working on a research paper where he will discuss how the seismicity reveals the location of the seismogenically locked fault zone.


This map shows the various possible prehistoric earthquake rupture regions (patches) for the past 10,000 years. Goldfinger et al., 2012. These rupture scenarios have been adopted by the USGS hazards team that determines the seismic hazards for the USA.

Comments are closed.