AVO Great Sitkin GREEN/NORMAL – Seismicity returned to background levels. Alert level downgraded to GREEN/NORMAL.

Jul 15, 2019 19:39 – Seismic activity at Great Sitkin Volcano has decreased to background levels over the past few weeks. There is no evidence of eruptive activity in geophysical data streams or in satellite observations. Thus, AVO is decreasing the Aviation Color Code to GREEN and Alert Level to NORMAL.

Great Sitkin is monitored with a local real-time seismic network, which will typically allow AVO to detect changes in unrest that may lead to an explosive eruption. Rapid detection of an ash-producing eruption would be accomplished using a combination of seismic, infrasound, lightning, and …