For the second time in as many days, a powerful earthquake has rocked the Pacific Ocean near the Loyalty Islands, generating tsunami bulletins from various government agencies around the world. According to USGS, an earthquake with an initial magnitude of 7.4 but later reduced to 7.1 struck at 3:51 pm Hawaii time or 6:51 pm Pacific Time.  The area has been struck by a string of strong earthquakes; according to USGS, there have been 45 earthquakes just within the last 24 hours here, most of which were magnitude 5.1 or greater.  These earthquakes are on top of a magnitude 7.7 event that hit yesterday evening.

The National Weather Service Pacific Tsunami Warning Center (PTWC)  in Honolulu, Hawaii is warning that tsunami is possible on some coasts.  Specifically, Fiji, Kiribati, Vanuatu, and Wallis and Futuna can all see tsunami from this earthquake. “Actual amplitudes at the coast may vary from forecast amplitudes due to uncertainties in the forecast and local features. In particular maximum tsunami amplitudes on atolls and at locations with fringing barrier reefs will likely be much smaller than the forecast indicates,” the PTWC warns.

While the PTWC is alerting the possibility of tsunami from this potent earthquake, they are also quick to issue bulletins that Hawaii, Alaska, California, Oregon, and Washington are not in a risk zone of tsunami from this specific seismic event.

“A tsunami threat exists for parts of the Pacific located closer to the earthquake. However, based on all available data, there is no tsunami threat to Hawaii,” the PTWC wrote in a bulletin issued to Hawaii.

The National Weather Service’s National Tsunami Warning Center in Palmer, Alaska issued a similar bulletin for those in Alaska, Washington, Oregon, California, and the British Columbia coast of Canada. “Based on earthquake information and historic tsunami records, the earthquake is not expected to generate a tsunami.”

Tsunamis are giant waves caused by earthquakes or volcanic eruptions under the sea. Out in the depths of the ocean, tsunami waves do not dramatically increase in height. But as the waves travel inland, they build up to higher and higher heights as the depth of the ocean decreases. According to the National Ocean Service, the speed of tsunami waves depends on ocean depth rather than the distance from the source of the wave. Tsunami waves may travel as fast as jet planes over deep waters, only slowing down when reaching shallow waters. While tsunamis are often referred to as tidal waves, this name is discouraged by oceanographers because tides have little to do with these giant waves.