PETROPAVOVSK-KAMTACHATSKY, Russia (AP) — One of Russia’s most active volcanoes has erupted, sending a five-kilometer-high cloud of ash into the sky over the eastern Kamchatka Peninsula. A Code Red warning was briefly issued for aircraft.

The Shiveluch volcano began sputtering shortly after a powerful 7.0 magnitude earthquake struck off the east coast of Kamchatka early Sunday, volcanologists from the Russian Academy of Sciences say, warning that another, even stronger, earthquake could be imminent.

The Academy’s Institute of Volcanology and Seismology released a video showing the ash cloud over Shiveluch, which stretched for 490 kilometers east and southeast of the volcano.

The Ebeko volcano on the Kuril Islands also emitted ash 2.5 kilometers high, the institute said. It was not explicitly stated whether the eruptions were triggered by the earthquake.

A red-category ash cloud warning briefly put all aircraft in the region on alert, the Kamchatka Volcanic Eruption Response Team reported. A separate report by the official Tass news agency on Sunday said no commercial air traffic had been disrupted and no damage had been caused to aviation infrastructure.

The tremors in the region could be a harbinger of an even stronger earthquake in southeastern Kamchatka, Russian scientists warned. The Institute of Volcanology said a possible second quake could occur “within 24 hours” with a magnitude of nearly 9.0.

There were no initial reports of injuries from Sunday’s earthquake, according to Russian emergency officials. The quake struck six kilometers below the seabed and the epicenter was 108 kilometers southeast of the nearest city.

Russian news agencies reported the strongest earthquakes “in a long time,” citing residents of Petropavlovsk-Kamchatsky, a port city of more than 181,000 people located across from a bay with a major Russian submarine base.

On November 4, 1952, a magnitude 9.0 earthquake in Kamchatka caused damage but no fatalities, although it triggered 9.1-meter-high waves in Hawaii.

The Associated Press