Description: From Neal and McGimsey (1997): "Two seismic swarms occurred beneath Iliamna Volcano in southern Cook Inlet in 1996. The first occurred between May 10 to May 28. The second swarm began abruptly at the end of July and peaked in late August or early September. Earthquakes as large as M 3.2 and at rates of up to 82 per day were recorded. The swarm began to decay by late 1996 and appeared to be over by early February, 1997. Most of the earthquakes during both swarms were shallower than 5 km and nearly all were unequivocal volcano-tectonic (VT) events."
Waythomas and Miller (1999) summarize the activity as follows: "Elevated levels of seismic activity beneath Iliamna Volcano were recorded by the Alaska Volcano Observatory (AVO) in 1996 (McGimsey and Neal, 1997). Earthquakes as large as magnitude 3.2 and as many as 82 earthquakes per day were recorded between May and September 1996. During this period, an increased flux of carbon dioxide and sulfur dioxide gas was detected over the volcano."
Roman (2000) suggests that "[t]he coincidence of the swarms with increased volcanic gas emissions suggests hot new magma intruded beneath the volcano in 1996."