Cleveland Volcano, located in Alaska's Aleutian Islands about 45 miles west of the village of Nikolski, erupted for at least the sixth time in four years on Tuesday, according to the Alaska Volcano Observatory.

At about 2 p.m. Tuesday, a webcam pointed at Mount Cleveland observed an ash cloud rising in the distance to an estimated height of 35,000 feet. That height was estimated by a pilot report submitted by a pilot traveling in the vicinity. The aviation level is now at orange, which means pilots should exercise caution when traveling in the area.

The observatory noted that additional, unexpected eruptions were possible that could send additional ash above 20,000 feet, but data indicated that this eruption didn't last long. Cleveland is about 150 miles west of the bustling fishing town of Unalaska.

Cleveland most recently erupted in December 2011, when a 15,000-foot column of ash was observed by satellite.

Cleveland has been upgraded and downgraded numerous other times in recent years, with lava domes growing, subsiding, and occasional eruptions occurring. It has now erupted six times since January 2009, with one other event in September 2010 that may have been an eruption, but wasn't confirmable due to cloud cover obscuring satellite confirmation of an ash cloud.

This most recent eruption, if the 35,000-foot estimate holds true, is the highest tephra cloud emitted from the peak since 2001, when an eruption pushed ash all the way to 39,000 feet.

Cleveland is among Alaska's most active volcanoes, but scientists have no real-time monitoring on its home island of Chuginadak, including seismic monitoring. Read more, and keep an eye on Mount Cleveland, at the Alaska Volcano Observatory.