Underground carbon sequestration is a promising approach to fight climate change, yet there are major obstacles to overcome before this technology can be applied on a large scale. A new study from Japan may address one such obstacle by identifying how to continuously and affordably monitor carbon reservoirs to detect leaks or other changes that require attention. The article, "4 cm Portable Active Seismic Source (PASS) for Meter- to Kilometer-Scale Imaging and Monitoring of Subsurface Structures," was published in Seismological Research Letters