The Chile subduction zone is emerging as a primary study site of the SZ4D Initiative. Specifically, central Chile (the region between 28˚S-34˚S) has been identified as a target for future onshore/offshore instrumentation intended to examine megathrust and faulting behavior (‘MegaArray’, Hilley et al., 2023). A detailed understanding of subsurface structure and velocity is essential to design the MegaArray and provide context for future observations that will come from it. However, subsurface imaging with active source seismic data in this region is sparse and was acquired with much less capable equipment than modern standards. Most of the existing lines were acquired with 3km or shorter streamers, which limits image quality and velocity models of the deep structure. We are planning a new community seismic imaging experiment with the R/V Langseth to acquire long-streamer multichannel seismic reflection data and wide-angle reflection and refraction data recorded by ocean bottom and onshore seismometers. This project will provide modern seismic images of ~ 900 km of the central Chilean margin. We aim to make the data and data products of this experiment accessible to the scientific community as soon as they are available. Through this virtual workshop, we are seeking input from the community to help design and plan this project so that it will maximize opportunities for scientific investigation and collaboration within the SZ4D program.

This ~3-hr long virtual workshop took place on September 26, 2023 and consisted of two talk sessions (1hr 45 min), a breakout group discussion (45 min), and report back/synthesis (30 min).