REYKJAVIK, Iceland (AP) — For all the worldwide chaos that Iceland’s volcano has already created, it may just be the opening act.

Scientists fear tremors at the Eyjafjallajokull (ay-yah-FYAH-lah-yer-kuhl) volcano could trigger an even more dangerous eruption at the nearby Katla volcano — creating a worst-case scenario for the airline industry and travelers around the globe.

A Katla eruption would be 10 times stronger and shoot higher and larger plumes of ash into the air than its smaller neighbor, which has already brought European air travel to a standstill for five days and promises severe travel delays for days more.

The two volcanos are side by side in southern Iceland, about 12 miles (20 kilometers) apart and thought to be connected by a network of magma channels.

Katla, however, is buried under ice 550 yards (500 meters) thick — the massive Myrdalsjokull glacier, one of Iceland’s largest.

That means it has more than twice the amount of ice that the current eruption has burned through — threatening a new and possibly longer aviation standstill across Europe.

Katla showed no signs of activity Tuesday, according to scientists who monitor it with seismic sensors, but they were still wary.

Pall Einarsson, professor of geophysics at the Institute of Earth Sciences at the University of Iceland, said one volcanic eruption sometimes causes a nearby volcano to explode, and Katla and Eyjafjallajokull have been active in tandem in the past.

In fact, the last three times that Eyjafjallajokull erupted, Katla did as well.

Katla also typically awakens every 80 years or so, and having last exploded in 1918 is now slightly overdue.

That notion is frightening for nearby villagers, who would have to quickly evacuate to avoid the flash floods that would rip down Katla’s slopes.

Even last week’s eruption generated spectacular cascades of melted water and ice chunks the size of houses when burning gases and molten earth carved through the glacier.

Svenn Palsson, the 48-year-old mayor of the coastal village of Vik, said residents are going over evacuation plans now just in case.

With a population of 300, Vik has been covered in 3 millimeters (0.12 inches) of ash from the Eyjafjallajokull eruption, but the real concern is Katla.

Residents would have two to three hours to reach the safety of a shelter if the volcano erupted and caused the ice to melt quickly.

“We have practiced and can do it in 30 minutes,” Palsson said.

Katla’s substantial ice cap is a major worry because it’s that mixture of melting cold water and lava that causes explosions and for ash to shoot into high altitudes.

• Carolo Piovano