A “nothing burger” is something that first seems very significant but in the end amounts to nothing. The big tsunami that was expected after the massive earthquake near Russia’s Kamchatka Peninsula on July 30 was just that — a big, fat nothing burger.
And it is abundantly clear that the earthquake did not cause the tidal surge witnessed that evening in Brgy. Soboc, Viga.
But the earthquake struck fear into the hearts of Catandunganons — for good reason — and PhiVolcs, the Philippine Institute of Volcanology and Seismology, did absolutely the correct thing by immediately issuing a tsunami alert.
The 8.8 earthquake, as measured on the Richter Scale, was one of the most powerful ever recorded, yet it did not produce the massive tsunamis everyone expected.
On a Mercator projection map, it appears that Japan might deflect any tsunami headed this way from Kamchatka to Luzon, but following the Great-Circle path, there are no major land masses between eastern Luzon and the infamous Kuril-Kamchatka Trench, site of last month’s quake.
Fears were justified because undersea earthquakes produce tsunamis that are more destructive than land-based quakes. This is because tsunamis travel at speed across vast distances of ocean with little resistance and wreak havoc on heavily populated coastal regions far away. Not to mention that Kamchatka has a 250-year history of producing megathrust earthquakes, which is to say, “very big ones.”
The 2004 Indian Ocean tsunami was triggered by a 9.1 magnitude earthquake off the west coast of Sumatra, Indonesia. That tremblor produced a 51-meter wave near Banda Aceh and killed 230,000 people in 14 countries. The Philippines was spared only because there are many landmasses — the thousands of islands of Indonesia and Malaysia — that blocked the tsunami from reaching Philippine shores with force.
The 2011 Tohoku earthquake in Japan and the resulting tsunami killed approximately 20,000 people, but the death toll was relatively low because Japan has a long history of tsunamis and is well prepared.
Indeed, the word tsunami is the romanization of a Japanese phrase that means “harbour wave”.
The largest tsunami ever recorded was an astonishing — and this looks like a typo, but it’s not — 524 meters in Alaska in 1958. Google it.
Land-based quakes are highly destructive only when they occur in densely populated areas, such as China’s Sichuan Province in 2008 when a 7.9 magnitude quake killed 87,000 people, mainly from collapsing buildings and landslides. In Haiti in 2010 a 7.0 earthquake killed 137,000 people, mainly from collapsing buildings in Port-au-Prince. And in southwestern Turkey and northwestern Syria in 2023, a 7.8 magnitude quake killed as many as 62,000 people in collapsing buildings.
Despite the strength of the most recent quake — the sixth-strongest earthquake in recorded history — the resulting tsunami waves were moderate, reaching about four meters in some areas like Severo-Kurilsk, Russia, but less than one meter in Hawaii and on the West Coast of the United States.
There are several reasons why this earthquake did not generate a major tsunami.
Tsunamis occur when an earthquake causes significant vertical displacement of the seafloor, pushing large volumes of water upward. The Kamchatka earthquake occurred in a so-calleld “subduction zone” where two tectonic plates meet: Off the east coast of Russia, the Pacific Plate slides beneath the North American Plate, and while such faults usually produce large tsunamis due to vertical motion of the seabed, the specific characteristics of this quake’s movement limited the effect.
The quake was shallow, with a depth of 20.7 kilometers, so the slip had less vertical displacement than normal, and there was more horizontal motion than usual, reducing the amount of water displaced but still registering high on the Richter Scale.
The direction in which the earthquake’s rupture faced also influenced the tsunami’s size. The fault rupture extended approximately 500 kilometers southwest along the subduction zone from the epicenter toward the Kuril Islands.
This orientation directed the tsunami waves toward the open ocean rather than directly at densely populated coastal areas to the south, including the Philippines.
As for the tidal surge in Brgy. Soboc, from the available scientific evidence, it is clear that the surge was not due to a Kamchatka tsunami.
The numbers speak for themselves. The earthquake occurred at 7:24 a.m. Philippine Standard Time, and the tidal surge at Soboc was witnessed at 9 p.m. PST, or 13 hours and 30 minutes later.
However, tsunamis travel at 700 to 800 kph, averaging approximately 750 kph, depending on the shape of the ocean floor. The line-of-sight Grand-Circle path from the earthquake’s epicenter to Viga is 5,339 kilometers. This means that any tsunami should have arrived at Soboc in the early afternoon, six and a half to seven and a half hours later. PhiVolcs said it arrived around 1:20 to 2:40 p.m., which aligns with this observation.
Tsunami waves are not just a single wave, but a series of three to 10 waves in a so-called “wave train”. The biggest wave is not the first one, but usually the second or third wave, with wavelengths of 100 to 200 kilometers and 10 to 20 minutes apart. In the case of Soboc , it is estimated that there were three to six waves in a one-hour window, implying periods of one to 20 minutes in the 1:20 to 2:40 time frame.
Because the tidal surge in Soboc, Viga, was not caused by the Kamchatka tsunami, then the best explanation is a combination of wind and tidal factors together with the long-predicted sea-level rise.
While exact wind speed and direction for Soboc at the time are not available, extracting from nearby records one can safely estimate that the wind at 9 p.m. was from the northeast at 14 kph, meaning that it was blowing towards the shore. And the high tide on the evening of July 30 occurred at 9:47 p.m. and was 1.31 meters, which is not high but higher than normal.
Finally, the sea level off the coast of Viga has risen 6 to 7 centimeters over the past 10 years, and the tidal surge may be a harbinger of things to come.
Bryce McIntyre, PhD, resides San Andres. He holds a doctoral degree from Stanford University, Palo Alto, California, USA.