|Start:||May 4, 2013 ||Observed|
|Stop:||March 6, 2014 ||Observed|
|Lava flow: ||
|Tephra plume: ||
|Duration: ||intermittent activity for 10 months ||
|ColHeight: ||5000 m ||
AVO infrasound monitoring detected multiple explosions at Cleveland volcano on May 4, 2013. The first was at 5 am AKDT, followed by two more at 7:17 am and 11:44 am. Infrasound signals suggest that these explosions were relatively short in duration. A small, low-level ash cloud and elevated summit thermal temperatures were observed in satellite imagery. These explosions transitioned to a continuous, low-level eruption characterized by long duration airwave signals, measured on the nearby Okmok seismic network 120 km (80 mi) to the northeast.
On Sunday, May 5, this eruption continued, although the amplitude of the Cleveland infrasonic tremor, as measured by the ground-coupled airwaves on the nearby Okmok seismic network decreased from its peak activity of the evening of May 4. Satellite data on Sunday morning showed highly elevated surface temperatures at the summit, as well low-level emissions of gas, steam, and minor amounts of ash over the past day, with a faint plume extending eastward below 15,000 ft.
Further explosions were detected via infrasound at 11:23 PM AKDT on May 5 (7:23 UTC May 6), 8:00 AM AKDT on May 6 (16:00 UTC), and 12:30 pm AKDT (20:30 UTC) on May 6. Infrasonic data suggests that the eruption has continued to wane since Sunday.
Intermittent clear views of the volcano showed a 1.5 km long lava flow down the southeast flank, steaming, and thermal anomalies. As of the end of May, thermal anomalies at Cleveland are consistent with a cooling lava flow.
On June 4, citing no explosions detected from Cleveland since May 6, and no evidence for lava effusion since May 13, AVO lowered the aviation color code to YELLOW and the volcano alert level to ADVISORY. On June 9, elevated surface temperatures were detected at Cleveland, but not seen again through the rest of the month.
On July 1, AVO infrasound detected two possible small atmospheric disturbances from Cleveland at 8:50 pm and 11:20 pm. These atmospheric disturbances may be the result of small explosions or possibly rockfall events. No elevated surface temperatures or other signs of unrest were observed in satellite images.
During the week of July 21, elevated surface temperatures were again intermittently observed in satellite data. A distinct plume was observed in satellite imagery on July 24 from 7:22 am until 5:24 pm. This plume extended 100 miles southwest and was likely primarily steam and gas. On July 28, another possible plume was detected, extending about 50 miles to the northwest.
Throughout most of August, no anomalous activity was observed at Cleveland Volcano. In late August, a few possible faint thermal features were observed, but these were not persistent.
On Saturday, September 7, a weak thermal anomaly was detected in satellite imagery at Cleveland.
In early October, AVO detected three short-duration explosions from Cleveland volcano using distant infrasound (pressure) sensor data. None of these explosions produced an ash cloud that could be detected in satellite images.
No other activity was observed until mid-November - a weakly elevated surface temperature was observed in one satellite image.
At 4:31 UTC November 26, 2013, an explosion was detected at Cleveland. No ash was seen in satellite imagery. Typical weakly elevated temperatures were observed on November 29.
Cleveland began 2014 with three explosions generating minor ash plumes. Explosions were detected on December 28, December 30, and January 2. On January 2, citing increased explosions and minor ash plumes, AVO raised the Aviation Color Code and Alert Level to ORANGE/WATCH. Analysis of satellite, wind, and ash dispersion data indicates that the Dec 30 and Jan 2 plumes probably did not reach more than 15,000 ft above sea level. No new activity was observed after the January 2 explosion, and AVO lowered the Color Code/Alert Level to YELLOW/ADVISORY on January 10, 2014.
Other than weakly elevated thermal anomalies in satellite imagery, no activity was observed at Cleveland until February 19, 2014 when a small steam plume was observed. On February 24, satellite data detected increased heat at Cleveland's summit. The following day, infrasound and lightning and alarms detected two small explosions at Cleveland Volcano at about 4:17 UTC February 25 (19:17 AKST February 24) and 10:35 UTC (1:35 AKST) February 25. Satellite data available several hours after these events occurred confirm that small ash clouds were generated by the explosions. The events were brief, and the estimated altitude of the drifting ash clouds was about 5 km (16,000 ft) asl. Satellite obsevations following the explosion show deposits of ash and large lava blocks on the upper flanks, extending 2.5 km (1.5 mi) from the summit. This suggests that these explosions were more energetic than those commonly observed over the past several years. However the ash emissions were brief and relatively low altitude, typical of recent Cleveland activity. The Color Code/Alert Level remained at YELLOW/ADVISORY.
In March 2014, low-level unrest continued at Cleveland; during the first week of March, satellite images showed slightly elevated temperatures at the summit of the volcano. On the evening of March 6, residents of Nikolski reported small bursts of ash rising less than 1,000 ft above the sumit; these puffs were too small and too brief to be seen by satellite or detected on distant seismic and infrasound networks.