Early Wednesday morning, a powerful earthquake, one of the largest ever recorded, struck off the coast of the Kamchatka Peninsula in Russia. Tsunami centers along the Pacific coastline quickly sprung into action, issuing warnings for the potential of colossal ocean waves that are often generated by big earthquakes.

But later in the morning, the centers began to downgrade or retire those warnings in some places, including parts of California, Hawaii, China and Japan, as the big waves failed to appear. What happened?

According to Diego Melgar, a geophysicist at the University of Oregon, part of the reason the tsunamis were weaker than anticipated may have to do with the size of the earthquake. “There’s big,” he said. “And then there’s really, really, really big.”

The most recent event had an estimated magnitude of 8.7 or 8.8 on the scale scientists use to measure the strength of earthquakes, according to Dr. Melgar. By contrast, catastrophic tsunamis in the past, including a wave that struck Indonesia in 2004 and another that hit Japan in 2011, were about a magnitude 9.

That may sound comparable to Wednesday’s quake, Dr. Melgar said, but is significantly bigger. That’s because the earthquake scale is logarithmic: A magnitude 9 event possesses about 10 times as much energy as a magnitude 8.7 event, and about three times as much energy as a magnitude 8.8 event.

Wednesday’s earthquake occurred along a subduction zone, where one of Earth’s tectonic plates slides under another. This can cause the seafloor to move up and down, creating a wave that propagates across the ocean.