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Visit USGS to see a graph showing how the colors on this map correlate with the intensity of the earthquake from the February 13, 2021, Japan earthquake. In general, on this map, yellow indicates strong tremors. Notice that Fukushima is labeled on this map and is within the strong shaking area. Image via USGS.
A strong 7.1 magnitude earthquake struck Japan on Saturday, February 13, 2021. The earthquake struck off the east coast of Japan, near the epicenter of the massive 2011 magnitude 9.0 Tohoku earthquake, which triggered a massive tsunami. The 2011 earthquake and tsunami caused about 20,000 deaths and started a major nuclear accident at the Fukushima Daiichi nuclear power plant, the most serious nuclear accident the world has seen since Chernobyl in 1986. The Japan Meteorological Agency rated the earthquake Saturday as a “aftershock” of the 2011 Earthquake. Aftershocks from such large earthquakes can apparently continue for a few years. Additionally, Saturday’s strong earthquake occurred just weeks before the 10th anniversary of the Tohoku earthquake and tsunami.
The quake occurred at 11:08 pm local time (14:08 UTC) at a depth of 37 miles (60 km) in the Pacific. Milder aftershocks followed Saturday’s magnitude 7.1 earthquake.
No tsunami warning was issued. The BBC reported:
There are reports of about 50 people injured, authorities say, and nearly a million homes are without power.
Japan is a nation prone to earthquakes. It is located along the Pacific Ring of Fire, a region that surrounds the Pacific Ocean, where about 90 percent of all the world’s earthquakes occur and 80 percent of the largest. According to Reuters, about 20 percent of the world’s earthquakes of magnitude 6 or greater occur along the Ring of Fire. Reuters also said that an earthquake occurs in Japan at least every five minutes, and each year there are up to 2,000 earthquakes that people can feel. USGS reported:
Large earthquakes in the vicinity of Japan and Taiwan have been destructive and deadly. The region’s high population density makes shallow earthquakes especially dangerous. Since 1900 there have been 13 earthquakes (9 in Japan, 4 in Taiwan) each causing more than 1,000 deaths, leading to a total of nearly 200,000 earthquake-related deaths. In January 1995, an earthquake that broke a southern branch of Japan’s Median Tectonic Line near the city of Kobe (population 1.5 million) killed more than 5,000 people. The 1923 Kanto earthquake shook both Yokohama (with a population of 500,000 at the time) and Tokyo (with a population of 2.1 million), killing 142,000 people. The earthquake also started fires that burned 90% of the buildings in Yokohama and 40% of the buildings in Tokyo. Most recently, the M9.0 Tohoku earthquake, which broke a 400 km stretch of the plate boundary of the subduction zone east of Honshu, and the tsunami it generated caused more than 20,000 deaths.
The Tohoku earthquake of 2011 was the most powerful earthquake ever recorded in Japan and the fourth most powerful earthquake in the world since modern records began in 1900.
A helicopter, flying over the port of Sendai, Japan, to deliver food to the survivors of the 9.0 magnitude Tohoku earthquake and tsunami, captured this scene. Image via Wikimedia Commons
Bottom line: A 7.1 magnitude earthquake off the east coast of Japan on Saturday February 13, 2021 was a “aftershock” of the 2011 magnitude 9.0 Tohoku earthquake.
