A series of strong earthquakes rocked and continue to rock portions of the Pacific Ocean near the Loyalty Islands, keeping the National Weather Service’s Pacific Tsunami Warning Center busy and on their toes today. In the last day, there have been 43 earthquakes in the area that were 3.5 or greater magnitude. Of those, three were strong enough to create a tsunami. Fortunately, the quakes haven’t triggered a Pacific-wide tsunami as of this article’s publishing time.
The Loyalty Islands Province is one of three administrative subdivisions of New Caledonia encompassing the Loyalty Island archipelago in the Pacific, which are located northeast of the New Caledonian mainland of Grande Terre. As of 2019, the islands had a population of 18,300.
While the Loyalty Islands doesn’t have much to shake, the world’s largest ocean does. According to UNESCO and the International Tsunami Information Center, it usually takes an earthquake with a Richter magnitude exceeding 7.5 to produce a destructive tsunami. Most tsunamis are generated by shallow, great earthquakes at subductions zones. More than 80% of the world’s tsunamis occur in the Pacific along its Ring of Fire subduction zones; today’s activity was near such a zone.
When these plates move past each other in these subduction zones, they cause large earthquakes, which tilt, offset, or displace large areas of the ocean floor. The sudden vertical displacements over such large areas disturb the ocean’s surface, displace water, and generate destructive tsunami waves. The waves can travel great distances from the source region, spreading destruction along their path.
Today, the National Weather Service’s Pacific Tsunami Warning Center (PTWC) issued numerous advisories on three strong quakes: a 7.9, a 7.7, and a 6.7. The PTWC is one of two tsunami warning centers that are operated by NOAA in the United States. Located at Ewa Beach on the Hawaiian island of Oahu, the PTWC is part of an international tsunami warning system program and serves as the operational center for the Pacific in issuing bulletins and warnings to participating members and other nations in the Pacific Ocean area of responsibility. It is also the regional warning center for the State of Hawaii. The other tsunami warning center is the National Tsunami Warning Center (NTWC) in Palmer, Alaska, serving all coastal regions of Canada and the United States except Hawaii, the Caribbean Sea and the Gulf of Mexico.
The PTWC has issued bulletins saying that none of today’s quakes posed a tsunami threat to Hawaii, Alaska, or the rest of the U.S. / Canada / Mexico west coast. While a tsunami was generated and threatened portions of New Zealand, Fiji, and Vanuatu, no widespread, Pacific-wide tsunami occurred.
Nevertheless, the PTWC remains on alert should a bigger earthquake occur within today’s swarm. Or should a tsunami threat be unveiled elsewhere around the U.S..