Alaska Volcano Observatory

From Cameron and others, 2017: "Beginning on October 7, the AVO seismic network recorded an earthquake swarm centered roughly 15 km (9.3 mi) northwest of Mount Martin in an area where about 10 earthquakes per year are recorded. Twenty-six earthquakes were recorded on October 7, and, over the next 5 days, a total of 40 earthquakes were recorded. The largest earthquake in the swarm was a M1.8 on October 7. Seismicity in the Katmai region is dominated by earthquakes at volcanic centers; this swarm occurred in an established cluster of seismicity, closest to Mount Martin. The cluster of seismicity is dominated by shallow (less than 10 km [6.2 mi] deep) earthquakes with calculated magnitudes less than M2. No specific cause has been identified for the long-lived seismicity at this location.
"On November 24, observers in King Salmon emailed AVO about robust steam plumes rising about 300 m (about 1,000 ft) above Mount Martin. Observers reported that the plumes continued until the evening of November 25, after which they were no longer visible from King Salmon. These fumarolic vapor plumes are common at Mount Martin (McGimsey and Neal, 1996; McGimsey and Wallace, 1999; Neal and others, 2005; McGimsey and others, 2007; Herrick and others, 2014)."