Alexei Morozov, a senior researcher at the Seismic Hazards Laboratory of the Institute of Earth Physics of the Russian Academy of Sciences, stated that the earthquake that struck Sakhalin and the earthquake that struck Japan are unrelated.
According to him, strong aftershocks are not expected in Sakhalin, explaining: “Every strong earthquake causes aftershocks, but their strength is always less than the strength of the main earthquake, and their number gradually decreases. In the case of the Sakhalin earthquake, only one aftershock of magnitude 3.2 was recorded, while earthquakes of magnitude around 5.2 are not usually accompanied by large aftershocks.”
He pointed out that Sakhalin Island lies at the intersection of several tectonic plates, making it regularly prone to earthquakes ranging from magnitude 5 to 6. He added that the earthquake's depth of 50 kilometers helped to mitigate its impact, while the powerful earthquake that struck Japan at a depth of 10 kilometers in the ocean triggered a tsunami.
Morozov said: "These are different earthquakes, even though both Japan and Sakhalin are located within the Pacific Ring of Fire, which is the most seismically active region on the planet, where about 90% of earthquakes occur."
According to the Sakhalin branch of the Unified Geophysical Service of the Russian Academy of Sciences, an earthquake measuring 5.2 on the Richter scale struck Sakhalin Island at 8:03 PM local time (12:03 PM Moscow time) on April 19. Its epicenter was located at a depth of 50 kilometers and 262 kilometers from the village of Redovo. Approximately 40 minutes later, an aftershock measuring 3.2 on the Richter scale occurred at a depth of 9 kilometers and 19 kilometers from the village of Belvo.
As for the Japan earthquake, it occurred on April 20 in the Pacific Ocean east of the coast of the Tohoku region in the northeast of the country, and its magnitude was about 7.5 according to the National Meteorological Agency, which warned of the possibility of a tsunami with a height of up to 3 meters.
