From Miller and others (1998): "A trapper living on the island in 1906 experienced several earthquakes and witnessed lava pouring down both east and west sides of the cone. Coats (1956) interpreted these flows to be the ones now present on the northeast and southwest slopes of Kanaga Volcano."
Coats (1956): "An eruption in May 1906 was reported in a letter to the writer from Simeon Oliver, teacher at Atka, who obtained his information from William Dirks of Atka. According to Dirks, who was trapping near Kanaga Volcano at the time, earthquakes occurred and lava poured down the east and west sides of the cone to the sea. It is possible that these lava flows are the ones now present on the southwest and northeast sides of the cone; however, only one of them reached the sea."

From Miller and others (1998): "The eruption was characterized by steam and ash plumes rising to as high as 7.5 km and drifting a few tens of kilometers downwind, lava extrusion within the summit crater, and minor avalanching of incandescent debris down the north flank reaching the sea in some cases (Neal and others, 1995). Strong sulfur odors were detected on occasion by ground observers in Adak, 33 km to the east."
From Neal and others (1996): "Report of increased steaming by U.S. Navy on 2-17-93 (Note: Neal and others (1995) report the first increased steaming observation incorrectly as April, 1993). Additional pilot reports of increased steaming in April and on 12-29-93; eruption begins in January, 1994.
From Neal and others (1995): "Increased steaming from the summit crater and upper flank fumaroles was first reported to AVO on December 29, 1993. (However, AVO subsequently learned that pilots had noted increased steaming as early as April, 1993). Beginning in early January, 1994, minor ash plumes usually rising < 1 km (3,280 ft) over the summit were reported by pilots and residents of Adak. Photographs of Kanaga Volcano in late January confirmed that a linear vent system extended across the summit crater and part way down the east and west flanks. Ash and steam billowed from discrete segments of the vent and minor debris flow deposits, recognized as dark lobate tongues, extended from the trace of the fissure.
"The eruption continued intermittently at a low level into October, 1994. Sightings of ash plumes were hampered by the frequent poor weather which plagues the Aleutian Islands. Most observed eruptive plumes were relatively dilute, rising to altitudes of < 3 km (9,840 ft) and dropping ash onto the flanks of the volcano. During other times, only white steam plumes were visible rising to altitudes of typically < 1500 m (4,920 ft) above the volcano’s summit. At least two significant ash plumes were recorded over the course of this eruption: the first, to ~7.5 km (24,600 ft) occurred on February 21 and the second on August 18, when an eruption cloud reached ~4.5 km (14,760 ft) [see fig. 13 in original text]. A light dusting of ash fell on the community of Adak on August 20. Air traffic was disrupted on August 22 due to continuing low-level activity and cloudy conditions which prevented visual approaches to the Adak air field.
"Avalanching of incandescent fragmental debris down the north flank into the sea was first reported in April as 'lava flows' by U.S. Navy pilots. On June 20 aboard the USFWS R/V Tiglax just offshore north of the island, Joe Meehan reported that at 1:45 a.m. local time, during a full moon, the crew observed two incandescent streams of fragmental material cascading down the northwest flank from an elevation of approximately 760 m (2490 ft) to near the shoreline. The upper flanks and summit of the volcano were obscured by clouds so the exact origin of the streams could not be determined. The crew could also not confirm whether debris had reached the ocean. By late July, however, USFWS personnel observed avalanches reaching the ocean and producing powerful littoral explosions. They noted that a new headland had been created."
"Throughout 1994, Adak residents and pilots of aircraft approaching and departing Adak Island reported occasional sulfur smell under westerly wind conditions. AVHRR satellite imagery intermittently detected a hot spot near Kanaga Volcano summit through October 13."
From McGimsey and Neal (1996): "Based on satellite and ground-based observations, the eruption had significantly waned or ceased by late November, 1994. However, weather conditions in the Aleutians typically prevent direct observations for days or weeks at a time, and over the next six months, during breaks in the weather, observers in Adak continued to report minor steam plumes above the summit of Kanaga (Smithsonian Institution, v. 20, n. 4, 1995).
"On June 3-4, 1995, U.S. Fish and Wildlife Service (USFWS) personnel aboard the research vessel Tiglax observed steaming from the summit and from the area covered by 1994 avalanche deposits on the north flank. Two weeks later, on June 19, a pilot reported seeing possible fresh ash or bare ground due to snow-melt on the west flank, and a weak ash plume up to 300 m (1000 ft.) above the summit. An AVHRR satellite image from June 21 showed a steam plume extended north from Kanaga [see fig. 5 in original text].
"The following day, another pilot reported a dirty haze at summit elevation extending 25 km south. AVHRR satellite images recorded a few hours later confirmed a weak thermal anomaly at the summit and a plume extending about 180 km to the north, prompting AVO to issue an information release stating that a small eruption may have occurred at Kanaga. On June 23, the U.S. Navy
Meteorological Office in Adak reported a thin ash cloud at the summit. USCG C-130 pilots observed a dusting of ash on the flank and 3 active steam vents on the south flank (Smithsonian Institution, v. 20, n. 6, 1995). Poor weather prevented observation of the volcano for much of the next 2 months. Occasional observations from Adak confirmed that vigorous fumarolic activity continued high on the southeast flank and minor steaming was still occurring at the summit crater (Smithsonian Institution, v. 20, n. 8, 1995).
"The captain of the USFWS research vessel Tiglax (Kevin Bell) reported in mid-October that on October 1 he observed hot blocks cascading down ravines on the north and northwest flank from near the summit--which was obscured by clouds--to as far as sea level, leaving 'steaming contrails' in their wakes (fig. 6). He noted that the activity was similar to that which he had observed during the documented eruptive period of summer 1994, and that the activity would not have been visible from Adak. However, based on the lack of a corresponding satellite-image anomaly or an ash plume visible from Adak, AVO concluded that Kanaga was probably not erupting at that time; what the Tiglax captain witnessed was most likely the continued avalanching of unstable lava masses that accumulated on the northwest flank during 1993-94.
"No further activity was reported by pilots or ground observers, and no thermal anomalies were visible on satellite imagery for the remainder of 1995. The last 1995 AVO weekly update to include Kanaga was that of August 25 [1995]."

From Herrick and others (2014): "An increase in seismic activity at Kanaga was first noted on February 18 during a routine seismic check by AVO seismologist S. Stihler, who reported a tremor-like event (interpreted as a possible explosion) followed by smaller events over the next hour. A possible correlative airwave occurred on the Adak seismic station 40 km (25 mi) northeast of Kanaga about 2 minutes after the tremor event (M. Haney, USGS/AVO, written commun., 2012). Ten minutes after the tremor event, a faint ash signal in satellite images may have been a small ash cloud from Kanaga, drifting to the east at an altitude of about 6 km (19,700 ft) ASL. Based on these observations, AVO upgraded the Aviation Color Code and Volcano Alert Level to YELLOW/ADVISORY. Additional analysis of the seismic signal, 'reduced displacements,' showed relatively small values, consistent with hydrothermal or possibly phreatic activity (S. McNutt, UAFGI, written commun., 2012).
"Adak resident M. Tillion contacted AVO by telephone on February 19 to share photographs and observations of Kanaga on the day after the possible explosion at about 12:26 Adak time or 10:26 UTC. From the White Alice site, west of the community of Adak, a resident noted an acrid odor that caused throat irritation. Kanaga volcano, 37 km (23 mi) northwest of Adak, was steaming strongly from the summit; M. Tillion thought that the plume may have contained some ash but further analysis suggests these were just shadowed clouds. There was, however, evidence of tephra or flowage deposits on the eastern flank extending down from the summit area.
"Cloudy conditions prevented any direct observations throughout much of February. Slightly elevated surface temperatures at the summit were noted in satellite images on February 21. On February 23, four bursts of tremor-like events were recorded on the Kanaga network. Satellite images from February 26 showed that the summit crater was clear with no evidence of ongoing eruptive activity. Seismicity remained low and on March 2, AVO downgraded the Aviation Color Code and Volcano Alert Level to GREEN/NORMAL, where it remained for the rest of the year.
"Retrospectively, the combination of satellite images, aerial photographs, and field inspection demonstrated that a brief explosive event from Kanaga's summit had indeed occurred, modifying the summit crater and producing a very small tephra fall deposit. A March 5 satellite radar image clearly showed a new open fissure along the southern rim of the summit crater. The feature was about 600 m (1,970 ft) in length and continued a short distance down the upper western flank of the volcano. In places, the fissure was 15 m (50 ft) wide and white clouds of vapor issued from several points along the fissure. An additional fumarolic cloud issued from the 15-m-diameter (50-ft), circular hole in the bottom of the crater. On March 9, nearly 3 weeks after the explosion signal, no ejecta or ash fall deposits were noted in satellite images, however, additional snowfall and reworking on the steep flanks likely would have obscured any primary deposits. Given the transient nature of the event, the limited tephra fall, and residual steaming fissure, AVO concluded that this event was a sudden phreatic explosion originating in the shallow, hydrothermally active summit region of Kanaga. The orientation and location of the feature has no clear relationship to the 1993-1995 eruptive vent complex that involved effusion of lava and ash from both the summit crater and a fissure system on the upper eastern flank of the volcano (Neal and others, 1995; Waythomas and others, 2002).
"Notable plumes of white vapor from Kanaga's summit were seen throughout the spring by ship and airborne observers as well as Adak residents. Ship-based observers on April 1 suggested that three distinct locations along the fissure were producing the most intense clouds. At least one satellite image on April 1 showed a possible plume from the summit. Bursts of seismicity were noted in mid- and late April. The seismic record was hampered by periods of noise and scattered data outages in late spring and early summer.
"An AVO crew working via helicopter on the Kanaga seismic network in mid-June was able to describe the fissure and apparently new ash on the northern and eastern flanks; they were unable to land and inspect the volcano's summit area, however, due to high winds. Steam was steadily rising from the summit fissure. On June 20, a faint sulfur odor was detected at the KINC seismic station located 2 km (1 mi) to the east of the volcano summit; our limited experience on the volcano makes it difficult to know how atypical this observation is from normal conditions. The team noted traces of what appeared to them to be recent ash on the northern flank down to an elevation of about 250 m (820 ft) ASL.
"Aerial photographs by Roger Clifford in both summer and fall provided excellent views of the summit fissure. Figure 29 shows a summer image of the nearly snow-free Kanaga cone; the fissure can be seen wrapping around and just outboard of the summit crater rim. The maximum opening across the fissure is about 15 m (50 ft) and white vapor issues from several point sources within the fissure. In November, Roger Clifford captured the western extent of the fissure where it crosses the summit and extends about 100 m (330 ft) down the western flank.
"Brief episodes of elevated seismicity occurred during the rest of the year at Kanaga. On June 27, unusual, emergent seismic events were detected on records from the northern seismic stations of the Kanaga network. Periods of tremor also were noted. The significance of this seismicity with respect to the summit fissure or ongoing activity at Kanaga is unknown.
"Satellite and seismic data from before February 18 was further analyzed to look for any changes prior to the explosion and opening of the summit fissure. A satellite image from January14, 2012, showed no structure in the area later cut by the fissure, although the southern rim was bare and lightly steaming. In October 2011, an unusual series of low frequency earthquakes had been noted, but any relationship of this to the 2012 activity remains unclear.
"In response to this event, AVO established automated PUFF runs to simulate ash cloud trajectories in the event of a magmatic eruption, increased the frequency of daily satellite checks, and attempted limited field verification of events in conjunction with seismic network maintenance."

On December 19, 2023, AVO raised the alert levels at Kanaga Volcano to YELLOW/ADVISORY, stating: "A small explosion was detected at Kanaga Volcano overnight at 22:31 AKST Dec 18 (07:31 UTC Dec. 19), and AVO is increasing the Aviation Color Code to YELLOW and the Volcano Alert Level to ADVISORY. The event was detected in local infrasound and seismic data and was followed by elevated earthquake seismicity that is ongoing. No ash emisions have been observed in partly cloudy satellite images."
Increased earthquake activity followed the explosion, and satellite imagery taken afterwards showed a debris flow extending 0.9 miles northwest of the summit crater rim, and a series of northwest-southeast oriented fractures both within the summit crater and extending down the southeast flank. Minor steaming was observed when the weather was clear.
Elevated seismic activity was ongoing until January 2, when seismic stations (and webcams) for Kanaga went offline due to a weather-related outage. Satellite images of the volcano were obscured by clouds until two weeks later, when a clear view showed no further changes at the surface.
On January 28, connection to the seismic stations and webcams was restored. Webcam views showed steaming at the summit, and a few earthquakes were detected daily during the first week afterward. A period of weak seismic tremor was observed on January 31.
During February, earthquake rates dropped to a few per week.
On February 27, 2024, AVO lowered the alert levels to GREEN/NORMAL, stating that seismicity had decreased to background levels and satellite and webcam data showed no recent surface changes, elevated temperatures or gas emissions, though steaming was still sometimes present.