A powerful tsunami triggered by a massive undersea earthquake near Russia's Kamchatka Peninsula is now impacting Hawaii. The Pacific Tsunami Warning Center has recorded waves up to 4 feet on Oahu's northern coast, with multiple surges expected throughout the night. Honolulu's mayor is urging residents in low-lying areas to evacuate to higher ground as sirens echo across the islands. Air travel has been thrown into chaos, with flights canceled, rerouted, or turned around mid-air. Emergency services remain on high alert as the state braces for additional waves. Officials caution that tsunami events consist of multiple waves and that the threat is far from over.