NUKU'ALOFA, Tonga — Frightened Tongans fled to higher ground on Saturday after a massive volcanic eruption, heard in neighbouring countries, triggered tsunami warnings across the South Pacific."A 1.2 metre tsunami wave has been observed at Nuku'alofa," Australia's Bureau of Meteorology tweeted.The latest eruption of the Hunga Tonga-Hunga Ha'apai volcano came just a few hours