Tokyo: Two strong earthquakes rattled northern Japan on Thursday, but neither caused any apparent damage or a tsunami.

A magnitude-6.1 quake struck Thursday evening south of the northern island of Hokkaido, Japan’s Meteorological Agency said.

It hit about 465 miles (750 kilometers) northeast of Tokyo and 19 miles (30 kilometers) below the sea surface. The agency did not issue a tsunami warning.

About 3,900 households in the towns of Erimo and Samani lost electricity shortly after the quake, but power was restored about an hour later, according to the Hokkaido Electric Power Co.

The shaking was not felt in Tokyo, though a morning quake was.

That magnitude-6.0 temblor struck just off the coast near the nuclear power plant damaged by the March 11 earthquake and tsunami.

The two shakings are believed unrelated and did not affect the crippled Fukushima Dai-ichi plant or other nuclear plants in the region.

The March 11 magnitude-9.0 earthquake and tsunami wiped out large parts of Japan’s northeastern coast and left nearly 20,000 people dead or missing. The twin disasters also triggered a nuclear crisis, forcing about 100,000 people to flee their homes due to leaking radiation.

Japan lies on the “Ring of Fire” — an arc of earthquake and volcanic zones that stretches around the Pacific Rim. About 90 percent of the world’s quakes occur in the area.