Just after 11 p.m. EDT on April 18, a magnitude 7.2 earthquake shook in the North Pacific Ocean, just 155 miles from Kuril'sk, Russia, and 324 miles from Nemuro, Japan. This is the second major earthquake to occur in three days, as a 7.8 quake caused significant casualties in Iran and Pakistan on Tuesday.
Earthquake location from USGS
The United States Geological Survey reports that the earthquake was caused by normal faulting within the Pacific tectonic plate. It occurred around the Kuril-Kamchatka arc, "one of the most seismically active locations in the world," which runs for about 1,300 miles from Hokkaido, Japan, to Russia's Commander Islands.
NOAA's Pacific Tsunami Warning Center issued a statement moments later that no tsunami was expected. No causalities have been reported from the earthquake, which occurred at relatively shallow depth.