On May 4, 2013 the Alaska Volcano Observatory’s infrasound monitors detected an explosion at the Cleveland Volcano, which is located on the western half of Chuginadak Island, a remote and uninhabited island in the east central Aleutians. The short duration, low-level explosion registered at 13:00 UTC (5:00 a.m. Alaska Daylight Time).
Almost 10 hours later, at 22:50 UTC (2:50 p.m. AKDT), the Terra satellite flew over the region, allowing the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument aboard to acquire this set of images of the cloud-covered region.
The top image is a false-color image. It has been further enhanced by overlaying black lines to outline of the islands which are obscured from view by the thick cloud cover. In this image, ice and snow appear bright orange, land appears green and clouds appear white. In this image, the cold clouds are also tinted with orange. In the center of the image a long, wide volcanic plume can be clearly seen rising from Chuginadak Island and blowing to the northeast.
Rolling the cursor over the top image reveals a true-color image of the same event. Here the colors appear as if viewed by the human eye, and the landscape (cloud, ice and volcanic plume) are all equally white, and it is harder to discern the plume itself.
Due to the renewed explosive activity at the Cleveland Volcano, AVO increased the Volcano Alert Level/ Aviation Color Code to Watch/Orange on May 4. After the initial activity a low level eruption continued through 12:30 p.m. AKDT (20:30 UTC) on May 6. Although a heavy cloud cover remained over the region, infrasound data detected multiple explosions and near constant air wave signals during those two days. Satellite and webcam data suggested that emissions of gas, steam and small amounts of ash continued. Since May 6 there has been no new activity, and on May 11 the clouds parted over the Cleveland Volcano to allow views of a vigorous steam plum accompanied by a distinct thermal anomaly at the summit.