Drema IV is a planet that was tearing itself apart until the Enterprise secretly stopped the process.
Drema IV is the home of the Dremans, whose civilisation had not yet discovered life on other worlds. In Pen Pals the Enterprise surveyed the Drema system, and Wesley Crusher led a team studying why the planet was suffering severe geological instability.
The crew found that dilithium formations within the planet were causing the upheavals. Data had been speaking secretly with a Dreman girl, Sarjenka, and after Picard approved help, the Enterprise used probes to stop the process without the Dremans ever knowing.