The katric ark was an underground facility on Vulcan in the alternate reality created by Nero's temporal incursion of 2233. It was impenetrable to both communications and transporter signals.
In 2258, as Vulcan was on the verge of destruction due to an attack by Nero, the Vulcan High Council, including Sarek and his wife Amanda, retreated into the ark chamber in an effort to save the knowledge contained within. As this was occurring, Sarek and Amanda's son, Spock, arrived to evacuate the High Council. As they fled the ark chamber, two of the Vulcans were killed by falling debris. Spock and the Council emerged from the chamber on a cliff and awaited transport by the USS Enterprise, although Amanda was killed when the cliff gave way beneath her due to heavy seismic activity. Spock, Sarek, and three other Vulcans were successfully transported off the planet, thus saving the essence of Vulcan culture. (Star Trek)
See also
Background information
Roberto Orci, a co-writer and producer of the film Star Trek, confirmed a fan's suspicions that what the Vulcan elders in the katric ark in that film were doing was retrieving the katra of Surak and possibly the katras of other Vulcans – so that Sarek became the carrier of Surak's katra – and that the writers at least considered having one of the other elders carry the Kir'Shara from the katric ark. [1]
As demonstrated in a concept painting, the interior of the film's katric arc was originally planned to have a series of triangular stairways and a pillar of spiraling particles (either water or energy) floating in midair. According to Industrial Light & Magic art director Alex Jaeger, the idea of the fantastical pillar was discarded by producer/director J.J. Abrams as he deemed it to be "too sci-fi magical." A concept painting of the corridor leading to and from the katric ark was illustrated to look more spacious than how it appears in the film, with walls that seem more man-made than the ones in the movie. More successful was concept art showing the katric ark's cliff-side portal, which looks more-or-less identical to the one shown on-screen. (Star Trek - The Art of the Film, pp. 110 & 111)
ILM was involved in creating an establishing shot of the enormous statues inside the katric ark. (audio commentary, Star Trek Special Edition/Three-disc Blu-ray) Roger Guyett, the film's visual effects supervisor and second unit director, explained, "The temple was pretty much just a floor on a big greenscreen stage. ILM added all the walls and statues as digital set extensions." (Cinefex, No. 118, p. 59)
The exterior of the katric ark in Star Trek was partly filmed on location at Vasquez Rocks Natural Area Park in Agua Dulce, California. (Star Trek Encyclopedia, 4th ed., vol. 1, p. 404)