A "rift zone" refers to an area where tectonic plates on Earth's crust are slowly moving apart, creating a gap or rift. This movement can lead to volcanic eruptions, earthquakes, and the formation of new land. Full definition
Understanding these preexisting structures, they write, «Is a major task toward defining the evolution of rift zones and also has important implications for geothermal exploration, mineralization, and the assessment of volcanic hazard.» (sciencedaily.com)
UPDATE May 12, 2018 from the Hawaiian Volcano Observatory / USGS: Volcanic unrest in the lower East Rift Zone of K?lauea Volcano continues. (earthsky.org)
But the high - density rocks below the NMSZ redirect that pressure downward, putting faults in the buried rift zone under significantly more pressure than the surrounding terrain. (sciencemag.org)