Powerful magnitude 8.1 earthquake rattles New Zealand prompting tsunami warning A string of powerful earthquakes has New Zealand emergency officials on tsunami watch. On Friday, a magnitude 8.1 quake struck in the ocean off the country's northeast coastline. It was the third large quake to strike within hours. 3 very strong earthquakes have struck near New Zealand within 6 hours of one another. The 8.1 #earthquake has prompted a #Tsunami watch for Hawaii. The potential threat is still being evaluated there and for the west coast of North America by the Pacific Tsunami Warning Center. pic.twitter.com/yaaanJLw2M An offshore magnitude 7.3 quake awoke many people during the night and a third magnitude 7.4 struck shortly after in the same region.