Exploring an Offshore Geophysical Network for Cascadia Funded by Gordon and Betty Moore Found. Goal: Perform a feasibility study on instrumenting the offshore component of the subduction zone. - Analyze existing data and conduct modeling studies that will help inform a design. - Study existing observatories and emerging technologies. - Develop top-level engineering design. - Hold a workshop (April 2017). Final product will be a White Paper that provides the motivation, design alternatives, and implementation plan.

Motivation An offshore network would: Improve earthquake early warning from offshore events. Enable tsunami early warning and forecasts for secondary arrivals. Provide sustained, and continuous observations of the offshore environment to advance research. Allow us to better monitor changes in seismicity and deformation of the accretionary prism. Talking Points: An offshore network could enable improved hazard warning and improved understanding of subduction zone processes.

Conceptual Designs Nodal Design Hybrid Design S-Net Design

April 2017 Workshop: Goals Prioritize the scientific and hazard requirements for an offshore system. Seek feedback on possible designs and technologies for offshore observations. Provide a forum to explore new ideas and foster discussion. Get the scientists, engineers, state & federal agencies, & industry in the same room. Build a consensus on how to move forward and engage stakeholders.

April 2017 Workshop: Findings Feedback on high-level engineering concepts. Tsunami EW is a primary benefit of a real-time offshore network; Questions remain about the utility of BPR for TEW. High-Frequency coastal radar has strong potential for near- shore tsunami detection… Final system will need to have diverse instrumentation. Many see the value of the expandability of any system. To prioritize a system design, weight should be given to stations with proximity to where the population is located. To reducing risk associated with instruments- critical to use demonstrated technology. Keep it simple. Scientists prefer focused network; EW and monitoring advocates prefer dispersed network.

Exploring an Offshore Geophysical Network for Cascadia Next Steps Assimilating feedback from the workshop. Generating workshop report. Reconnaissance of S-NET and DONET. Wrap up sensitivity/engineering studies. Lobbying to DC. Write White Paper.