Seismicity has been increasing over the last few days at Semisopochnoi volcano, Alaska and now is characterized by nearly continuous tremor and frequent small explosion signals. The situation represents a significant increase in activity and the Alaska Volcano…
A series of small explosions and tremor bursts have been detected in seismic data at Semisopochnoi over the past 7 hours and are continuing, representing a significant uptick in activity, the Alaska Volcano Observatory (AVO) reported at 09:19 UTC on February 15,…
An eruption signature was detected at Semisopochnoi as strong tremor on local seismic and in regional infrasound networks on Adak Island, Alaska Volcano Observatory reported at 10:25 UTC on December 7, 2019. The event started at 09:26 UTC (00:26 AKST) on December 7…
Elevated seismicity that began under Semisopochnoi volcano, Alaska on July 17, 2019, increased overnight and was followed by a stronger tremor signal recorded at 07:39 UTC, July 18. In addition, an infrasound signal was produced on an infrasound array located 260 km…
Due to an increase in seismicity above background levels over at least the last 8 hours AVO is raising the Aviation Color Code to YELLOW and Alert Level to ADVISORY at Semisopochnoi. No explosive activity has been detected on the Adak infrasound array and clouds…
Strong seismic tremor consistent with an eruption was recorded at Semisopochnoi volcano starting at 04:47 UTC (20:47 AKDT) on October 26, 2018. Satellite data through 05:00 UTC showed a small ash cloud at about 3.6 km (12 000 feet) above sea level, the Alaska…
The Alaska Volcano Observatory raised the Aviation Color Code for Semisopochnoi stratovolcano to Yellow and the Volcano Alert Level to Advisory on September 16, 2018. This is the largest subaerial volcano of the western Aleutians. It's 20 km (12.4 miles) wide at…
Earthquake activity at Semisopochnoi volcano, Aleutian Islands that began in January continues, and has increased in intensity over the past few days, Alaska Volcano Observatory (AVO) reports.In addition, AVO detected brief periods of seismic tremor, which can indicate
A massive M7.9 earthquake (downgraded from M8.0) struck Aleutian Islands, Alaska on June 23, 2014, at 20:53 UTC. USGS is reporting depth of 107.5 km (66.8 miles). EMSC is reporting M7.9 at depth of 100 km.Epicenter was located 24 km (15 miles) S
A swarm of earthquakes started at Semisopochnoi volcano on June 9 and escalated on June 12 at approximately 20:00 UTC, the Alaska Volcano Observatory (AVO) reported yesterday.The continuation of this anomalous seismic activity prompted AVO to raise the Aviatio
