A volcano has erupted in Alaska, spewing ash more than nine miles into the sky. The first blast from Mount Redoubt occurred on Sunday morning and was followed by four smaller eruptions, the Alaska Volcano Observatory said. The 10,197ft (3,100) volcano, located 106 miles (170km) southwest of Alaska's largest city Anchorage, had been showing signs of a possible eruption for about two months. So far the city has been untouched by the volcanic ash, but planes have been warned to steer clear of the area. More eruptions are expected, according to experts. Tina Neal, a geologist at the Alaska Volcano Observatory, said: The volcano is still restless. We'll be watching it very closely. It is highly unstable still and further eruptions are likely." The volcano last rumbled to life in December 1989, erupting several times over a period of weeks. The eruptions sent ash plumes almost eight miles high, and the first blast nearly downed a KLM airliner.