The National Weather Service’s Pacific Tsunami Warning Center (PTWC) in Honolulu, Hawaii has issued several bulletins relating to a strong earthquake which rocked the Philippines earlier today. Despite the strong magnitude, 7.6, the PTWC says there is no threat of a Pacific-wide tsunami from this earthquake, allowing those in Hawaii, the U.S. and Canadian west coast, and elsewhere the chance to have a sigh of relief. Additionally, the PTWC has said the threat of tsunami even near the epicenter has now passed.
Thirty two earthquakes have struck the Philippines since the strong 7.6 earthquake struck at 9:37 am Eastern Time / 4:37 am Hawaii Time this morning. The 31 earthquakes, all considered aftershocks, have been on the strong side, with most rated at 5.4 or greater. There were also one 6.4 and two 6.2 magnitude aftershocks. The most recent, a magnitude 5.4, struck at 9:19 am Hawaii Time / 2:19 pm Eastern Time.
According to the PTWC, a minor tsunami of less than a foot struck Malakal Koror, Legaspi, and Davao today.
The PTWC issued 14 bulletins on this earthquake event, updating those in Canada, the United States west coast, Hawaii, Guam, and the Northern Mariana Islands with reports and forecasts of the unfolding seismic events.
While there was a risk of a local tsunami, the the PTWC said the threat didn’t travel far from the epicenter of the earthquakes. “Based on all available data, a destructive Pacific-wide tsunami is not expected,” said the PTWC in their bulletins.
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. The location, depth, movement, and intensity associated with today’s earthquake wasn’t enough to trigger a tsunami from today’s earthquake.