Alert level raised for Alaska's Semisopochnoi Volcano as tremors and ash spell trouble

Semisopochnoi Island is uninhabited, and the volcanic eruption poses no immediate danger to people.

However, volcanic ash rising from the Aleutians could be problematic for trans-Pacific aircraft travelling between Asia and North America.

Volcanic ash – tiny rock fragments – can create significant harm to aeroplanes that fly through them or boat and automobile engines that ingest ash-filled air.

Volcanic ash is hard and abrasive, and can quickly cause significant wear to various aeroplane parts such as propellers, turbo-compressor blades, and even cockpit windows.