As of April 4, 2009, AVO had recorded twenty-six volcanic eruptions and/or explosions at Redoubt volcano, although they singled out nineteen of them as most notable. The AVO refers to an eruption as any event which discharges ash into the atmosphere, while adding the term explosion for more vigorous events. The AVO did not rate and compare each eruption, although the 9:24 am eruption on March 26 reached an altitude of 65,000 feet making it the highest volcanic ash cloud to date during the 2009 phase of activity. The eruption on April 4 was described as being the biggest eruption to date. There were also periods when the volcano emitted notable amounts of steam but did not erupt.