Cleveland reported activity

Start:

May 4, 2013

Observed

Lava flow:
Tephra plume:

Description: 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.