Alaska Volcano Observatory

From Dixon and others (2015): "Mount Veniaminof Volcano is a frequently active volcano on the Alaska Peninsula. From 2002 through 2010, nearly continuous low-level eruptive activity waxed and waned, producing wispy plumes that were reported by pilots, recorded on satellite images, and observed in images from the Federal Aviation Administration (FAA) Web camera in Perryville, 35 km (22 mi) east of the volcano. Activity ceased during the first one-half of 2013. In early June 2013, a several-day period of abrupt and gradually increasing levels of seismic tremor heralded the onset of a largely effusive eruption from the intracaldera cinder cone (table 6 in original text). Over the next 5 months, ash emissions and Strombolian explosions accompanied by five lava flows poured down the flanks of the active cone and advanced onto the surrounding ice-filled caldera. This eruption constructed a new spatter cone within the summit crater of the main active cone (Waythomas, 2013).
"On June 7, 2013, gradually increasing, low-frequency tremor was recorded on two seismograph stations (VNWF and VNHG) as satellite images recorded elevated surface temperatures at the summit of the intracaldera cinder cone (fig. 10 in original text). The following day, June 8, in response to the continuing increase in seismic tremor, AVO upgraded the Aviation Color Code and Volcano Alert Level from GREEN/NORMAL to YELLOW/ADVISORY. Over the next several days, seismic tremor steadily increased. On June 13, seismicity levels and elevated surface temperatures at the summit of the cinder cone, as observed in satellite images indicated an eruption was likely underway. AVO issued a Volcanic Activity Notice (VAN) upgrading the Aviation Color Code and Volcano Alert Level from YELLOW/ADVISORY to ORANGE/WATCH. On June 14, ash deposits on the ice/snow-covered caldera floor were visible in satellite images, and the presence of lava on the cone was observed.
"Clear weather provided good views from the FAA Web camera, located in nearby Perryville, as the eruptive activity increased and produced minor ash clouds (fig. 11 in original text). Satellite views on June 18 confirmed the Strombolian eruption and effusion of a 100 m (330 ft) wide lava flow (Flow 1; flow numbers refer to those identified in figure 12 [in original text] down the southwestern flank of the main cinder cone). Interaction of the lava with the caldera snow and ice field at the base of the main cone generated water-rich, ashy plumes (fig. 13 in original text). Clear satellite views the following day showed active flow lobes advancing over the ice at the base of the cone (fig. 14 in original text).
"For the next couple of weeks, the activity continued with the southern flank flows (Flows 1 and 2) advancing and widening, with minor accumulations of ash on the caldera floor (figs. 15 and 25 in original text); Flow 2 descended east and adjacent to Flow 1, and Flow 3 advanced between and over the margins of Flows 1 and 2. The Strombolian eruption was visible in infrared satellite imagery, from the FAA Web camera in Perryville, and from several local lodges and remote camps (figs. 16 and 17 in original text).
"On July 16, AVO geologist Chris Waythomas visited the caldera by helicopter, making observations and taking the first close-up photographs documenting the lava flows and ice cauldron formation (figs. 18 and 19 in original text). These close-up images of the vent area showed a new cone of accumulated spatter nested within the summit crater of the main cone.
"By late July, the activity appeared to be waning as seismicity decreased, and reached a low level by August 2. In clear satellite views over this period, elevated surface temperatures were consistent with the still cooling, but no longer advancing, lava flow. On August 11, seismic tremor increased abruptly, and very high surface temperatures were observed in satellite images, suggesting that eruptive activity had resumed and lava again was flowing from the summit vent. Nighttime satellite images on August 12 confirmed lava erupting from the cone, and a clear morning view from the Perryville Web camera showed a minor ash column and cloud over the summit cone.
"On August 18, AVO geologist Game McGimsey accompanied Ben Edwards, Dickinson University, on a National Geographic Society-sponsored visit to the caldera to document the ongoing activity, particularly the interaction of lava flows and the surrounding ice field. The southern flank lava flows had coalesced and largely melted into the ice, enlarging the ice cauldrons documented in July by Chris Waythomas, USGS/AVO (fig. 20 in original text). Steam rose from the margins where the hottest parts of the flows were still in contact with ice and water.
"Strombolian explosions of incandescent lava and minor ash emissions were observed at the central active vent on August 18 (fig. 21 in original text). Two new lava flows issued either from tubes emerging from accumulations of spatter near the vent rim on the northeastern flank of the new cone, or from vents through the base of that cone. The flows descended to the ice field below, coalescing and forming another ice cauldron (fig. 22 in original text); forming Flow 4 (Waythomas, 2013). Voluminous steam generated by interactions of lava and ice/water obscured views into the cauldron. Forward Looking Infrared Radiometer (FLIR) images delineated the lava flows and hot spatter on the cone (fig. 22 in original text). As measured by the FLIR, maximum temperatures reached 700 to 800 degrees C.
"Elongated lobes of sediment extended from the southern side of the ice cauldron, forerunners to the fifth and final lava flow of the eruption (figs. 23 and 24 in original text). Eruptive activity continued unabated for the next 12 days, and on August 30, AVO issued a VAN to report the intense seismicity, lava fountaining, and ash emissions as high as 15,000-20,000 ft (4,570-6,100 m) ASL. This marked the strongest unrest and eruptive activity since the eruption began in June. Satellite images on September 6 indicated further development of the lava flows on the northeastern flank (Flow 4), expansion of the main ice cauldron at its base, and creation of a second ice cauldron. A new lobe of the lava flow (Flow 5) also appeared in the satellite images, advancing southward from the main cauldron of Flow 4. The flow was captured in aerial photographs the following day (fig. 24 in original text). This flow continued to advance for possibly another week, but, by September 19, no evidence of active lava flows was observed in satellite images. Seismicity had begun to decrease during the week and the eruption appeared to be waning.
"In response to the decrease in seismicity, and no evidence of eruptive activity in satellite and Web camera images, AVO issued a VAN on September 20 to downgrade the Aviation Color Code and Volcano Alert Level from ORANGE/WATCH to YELLOW/ADVISORY. An October 1 aerial image shows all five lava flows, partially snow covered, and only minor steam emissions from the summit vent (fig. 13 in original text).
"On October 6, an abrupt increase in seismic tremor and the observation of highly elevated surface temperature indicated a resumption of lava effusion, and AVO responded by upgrading the Aviation Color Code and Volcano Alert Level to ORANGE/WARNING. No ash emissions were observed, and within a few days, seismicity began decreasing in what would be a downward trend coincident with the final end of eruptive activity in 2013. The Aviation Color Code and Volcano Alert Level were downgraded on October 17 to YELLOW/ADVISORY. Throughout the remainder of 2013, occasional elevated surface temperatures were observed in satellite images consistent with the cooling lava flows, and steam emission from the summit vent was visible on clear days in Web camera images.
"The 2013 eruption of Veniaminof produced about 5 x 105 m3 of erupted lava, comparable in size to the 1983 eruption (Waythomas, 2013). A real-time seismic amplitude (RSAM) time series (Endo and Murray, 1991) from seismic station VNWF (fig. 11 in original text) is shown in figure 25 for the 5-month-long eruption, including significant eruptive events and color code changes (Waythomas, 2013). Before- and after-eruption views of the intracaldera cinder cone and geomorphic changes produced by the 2013 eruption are shown in figures 26 and 27 [in original text]."
From Cameron and others, 2017: "The volcano gradually returned to a state of rest, and by early July 2014, seismicity had returned to normal background levels. AVO downgraded the Aviation Color Code and Volcano Alert Level to GREEN/NORMAL on July 9, 2014. Minor steam emissions and cooling of the lava flows continued intermittently for the remainder of the year. Several episodes of low-frequency events and tremor bursts occurred over the last one-half of the year (for example, July 15, October 8, December 18) as reported by AVO seismologists; however, these events were not associated with eruptive activity and are interpreted as continued degassing of the magmatic system."