A compact, low-impact seismic source reshapes monitoring of offshore CO2 storage

We developed a low-cost, environmentally friendly seismic source for monitoring nearshore CO₂ storage sites where the operation of conventional large seismic vessels is impractical. The compact speaker-type source (<100 kg) is ∼100 times lighter than conventional airgun seismic sources, while still providing sufficient energy to monitor deep CO₂ reservoirs through stacking of highly repeatable signals. Field experiments demonstrate that stacking approximately 10 shots produces signal amplitudes exceeding those of a conventional small airgun source. Furthermore, at a planned CO 2 storage site, the CO 2 storage reservoir was successfully imaged to depths greater than 2 km in reflection seismic profiles, demonstrating the feasibility of monitoring injected CO 2 . The source can be deployed from small vessels, including autonomous surface vessels, and minimizes risk to marine life due to its low acoustic pressure. In addition, we confirm its compatibility with distributed acoustic sensing (DAS), enabling continuous, high spatiotemporal resolution monitoring. This seismic source has the potential to transform monitoring schemes for offshore CO 2 storage sites and provides a realistic pathway toward automated, low-cost, and scalable monitoring.