Why are tsunami waves hitting Japan after Kamchatka earthquake smaller, but those barreling towards Hawaii, Ecuador nearly 10 feet high?

Tsunami waves have started to crash along the coast of Russia's far east and some islands and Japan following the world’s sixth-most powerful earthquake on the Pacific Ocean seafloor in Kamchatka Peninsula on Wednesday. Hawaii in the US including the country’s and Canada’s western coast are also bracing for powerful waves as warnings and watches have been issued for many regions.

The massive earthquake on July 30 measuring 8.8 according to the US Geological Survey (USGS) had its epicenter nearly 74 miles (119 kilometers) southeast of Petropavlovsk-Kamchatsky in Russia’s Kamchatka Peninsula. The quake’s depth was 20.7 kilometers, prompting the USGS to issue tsunami warnings. Even parts of South America including Ecuador have issued tsunami warnings for regions along the Pacific coast.

USGS warning says Hawaii could face tsunami waves more than 3 meters (10 feet) high along some of its eastern coasts. The region along with Russia’s far east and Ecuador are likely to face the most ferocious tsunami waves even though the US state and the South American nation are several thousands of kilometers away from the earthquake epicenter.


Also Read: Tsunami waves slam Japan’s Hokkaido and Russia’s Kuril Islands after massive 8.8 quake off Kamchatka; Hawaii, Alaska on high alert

Japan’s northern regions and Russia’s Kuril Island were the first to be hit by tsunami waves after the quake. But the waves were enormous as expected. The waves which crashed into the above-mentioned regions were only about 1 to 1.5 feet high, even though the initial forecast was they would reach a height of up to 10 feet (3 meters).

These regions are closest to the quake epicenter in Kamchatka Peninsula with Japan’s northern islands just 1,000 miles (1,600 kilometers) away.

What US Tsunami Warning Syatem says?

However, US Tsunami Warning System maintains that Hawaii and Ecuador will face much bigger tsunami waves. While Hawaii is more that 3,000 miles (4,800 kilometers) away from the epicenter, Ecuador lies 8,000 miles (12,800 km) away from Kamchatka Peninsula.

Japan's Hokkaido, Ibaraki, Chiba, and Ishinomaki port in the north saw tsunami waves up to 50 centimeter, said Japan Meteorological Agency. The US state of Alaska, another region relatively closer to the earthquake epicenter was waves up to 30 centimeters lashing its shores.

So why are the tsunami waves hitting Japan smaller and those expected in Hawaii and Ecuador much higher?

According to seismologists, the strength and height of a tsunami depends on the nature and direction of the earthquake.

When an earthquake strikes under water on a sea or ocean floor, it displaces huge quantities of water resulting in a tsunami. The height and strength is directly dependent on the direction of the water displacement.

Also Read: Massive earthquake of magnitude 8.8 strikes Russia’s far east, biggest since 2011; details inside

The tsunami waves are pushed in the direction of the fault line rupture due to the quake. So the strongest and highest tsunami waves move out in one direction. While the seismic waves travel in all directions and the waves rise across all the basins, the maximum energy is in the direction of the rupture.

The Kamchatka earthquake released the maximum energy towards Hawaii and Ecuador. So, seismologists predict the highest tsunami waves will hit these regions even though they are several thousands of miles away from the quake.

The first waves will reach Hawaii around 7:17 p.m. HST (1:17 a.m. ET). These are expected to be 10 feet (3 meters) high. Other coasts in Hawaii will also be hit by waves reaching up to 3 to 9 feet (1-3 meters).