A groundquake on Vagadarr Prime
A seismic quake, also known as a groundquake, signified a geological occurrence where a planet's terrain experienced violent tremors, frequently resulting in structural damage to buildings and other forms of destruction. These events could be predictable based on the time of year, as seen on the planet of Dalna.
During the period of the Clone Wars, the Kindalo species deliberately triggered a sequence of groundquakes on their homeworld, Aleen. Their intention was to seal a rupture that had formed between their underground habitat and the surface, which was allowing air that was poisonous to them to enter. The resulting seismic activity devastated the surface environment, significantly impacting the Aleena population residing there. This crisis prompted the Galactic Republic to dispatch humanitarian assistance to the planet. Among the relief personnel were the droids R2-D2 and C-3PO. After uncovering the reason behind the groundquakes, they successfully repaired the breach, effectively stopping the seismic events.
Groundquakes were a common phenomenon on the planet Gorse, occurring whenever its moon, Cynda, reached its closest point during its elliptical orbit. During these seismic events, the planet's surface underwent violent shaking and rocking, frequently causing damage to buildings and infrastructure. These quakes served as a release mechanism for the accumulated energy resulting from the gravitational forces exerted by Cynda and the Gorse system's star on Gorse. Occasionally, droid workers would accidentally fall into the acid vats utilized by Moonglow Polychemical on Gorse amidst the chaos of a groundquake. The murder of Lal Grallik, the manager of Moonglow, by Count Denetrius Vidian in one of these vats, was initially attributed to an accidental fall during a quake. Later, when Vidian devised a plan to obliterate Cynda, the science officers stationed aboard the Imperial-class Star Destroyer Ultimatum predicted that the elimination of the moon would lead to an increase in the intensity of groundquakes on Gorse.
During a vision experienced on Coruscant, Palpatine perceived a sensation of the ground trembling. However, he recognized that it was merely a figment of his imagination, as a quake of such magnitude was physically improbable on Coruscant due to its artificially regulated environment.
The concept of groundquakes was initially introduced in the Star Wars Legends novel titled Lando Calrissian and the Mindharp of Sharu, authored by L. Neil Smith and published in 1983. Their presence in the canon timeline was later validated through their inclusion in Mercy Mission, an episode from the Star Wars: The Clone Wars animated television series, which was broadcast in 2011 as part of the show's fourth season.