A powerful undersea earthquake struck near Fiji on Tuesday, geologists said, and officials issued a tsunami alert for the local area. No damage or injuries were immediately reported. The quake, with a preliminary magnitude of 6.3, occurred at 3:16 p.m. about 255 kilometers northeast of Vanua Levu, the main tourist spot in Fiji's chain of islands, at a depth of 29 kilometers, the US Geological Survey reported. The survey initially reported a second quake nearby, much deeper and with a magnitude of 6.8. But the survey removed the second quake from it's Web site soon after details were posted. The survey says that when a large earthquake occurs it is common for seismological equipment in the area to incorrectly record multiple temblors, and that such glitches are quickly corrected on it's Web site.