Waitt and Beget (2009) summarize the 1883 eruption as follows: "1883 is the first Augustine eruption documented to some extent by contemporaneous written accounts: an unpublished logbook of the Alaska Commercial Company post situated atop the spit at English Bay, published summaries by Dall (1884), Davidson (1884), and Becker (1898), an unpublished letter and an unpublished mission report both of 1884, and field notes by J.E. Spurr in 1898.
"On the 6th of October 1883, Augustine Volcano -- or Chernoburoy (variously spelt) as the Russians knew it -- generated a tsunami and an ash plume experienced from English Bay 85 km away on the east mainland. The record book of the Alaska Commercial Company (1883) at Alexandrovsk (English Bay) records various routine data for 6 October 1883. Then this entry:
'At this Morning at 8.15 o'clock 4 Tidal Waves flowed with a westerly current, one following the other at a rate of 30 miles p. hour into the shore, the sea rising 20 feet above the usual Level. At the same time the air became black and foggy, and it began to thunder. With this at the same time it began to rain a finely Powdered Brimstone Ashes, which lasted for about 10 Minutes, and which covered all the parts of Land and everything to a depth of over 1/4 of a inch, clearing up at 9 o'clock A.M. Cause of occurrence: Eruption of the active Volcano at the Island of Chonoborough. Rain of Ashes commencing again at 11. o'clock A.M. and lasting all day.'
"And for 7 October:
'Volcano ejecting fire and heavy black Clouds of Smoke all day long.'
"The geographer William Dall (1884) rushed into print summary information derived from George Davidson (USCGS) and from a Capt. Sands and a Capt. Cullie (Alaska Commercial Company) observed from English Bay and then the sea:
'Smoke first arose from the peak in August. On the morning of Oct. 6 the inhabitants heard a heavy report, and saw smoke and flames issuing from the summit of the island. The sky became obscured, and a few hours later there was a shower of pumice-dust. About half-past eight o'clock the same day an earthquake wave, estimated at thirty feet height, rolled in upon the shore, deluging the houses on the lowland, and washing the boats and canoes from the beach. It was followed by others of less height. The ash fell to a depth of several inches, and darkness required lamps to be lighted. At night flames were seen issuing from the summit. After the first disturbances were over, it was found that the northern slope of the summit had fallen to the level of the . . . shore, and the mountain appeared as if split in two. . . . The cleft . . . crosses the island from east to west.'
"George Davidson, who for the USCGS mapped much of the Washington-Oregon-California coast in 1850-53 and the Alaska coast in 1867-69, was experienced with coastal ship captains and eyewitness reporting. Having been partly scooped of his own story by Dall, Davidson (1884) gives a more detailed account of Augustine's effects partly derived from 'settlers and fishing-parties' at English Bay:
'About eight o'clock on the morning of Oct. 6, 1883, the weather being beautifully clear, the wind light from the south-westward, and the tide at dead low water, the settlers and fishing-parties at English Harbor heard a heavy report to windward (Augustin bearing south-west by west three-fourths west by compass). So clear was the atmosphere that the opposite of north-western coast of the inlet was in clear view at a distance of more than 60 miles.
'When the heavy explosion was heard, vast and dense volumes of smoke were seen rolling out of the summit of St. Augustin, and moving to the north-eastward; and at the same time (according to a hunting-party in Kamishak Bay), a column of white vapor arose from the sea near the island, slowly ascending, and blending with the clouds. The sea was also greatly agitated and boiling, making it impossible for boats to land upon or to leave the island.
'From English Harbor . . . it was noticed that columns of smoke, as they gradually rose, spread over the visible heavens, and obscured the sky, doubtless under the influence of a higher current (probably north or northeast). Fine pumice-dust soon began to fall, but gently, some of it very fine, some very soft, without grit.
'At about twenty-five minutes past eight A.M., or twenty-five minutes after the great eruption, a great 'earthquake wave,' estimated as from twenty-five to thirty feet high, came upon Port Graham [English Bay] like a wall of water. It carried off all the fishing-boats from the point, and deluged the houses. This was followed, at intervals of about five minutes, by two other large waves, estimated at eighteen and fifteen feet; and during the day several large and irregular waves came into the harbor. The first wave took all the boats into the harbor, the receding wave swept them back again to the inlet, and they were finally stranded. Fortunately it was low water, or all of the people at the settlement must inevitably have been lost. The tides rise and fall about fourteen feet.
'These earthquake waves were felt at Kadiak [Kodiak], where they are doubtless on the register of the coast-survey tide-gauge at that place.'
"An indirect but independent record of the sea waves striking the Kenai Peninsula mainland exists in a report of the Russian Orthodox priest heading the Kenai mission, Heiromonk Nikita, who after a visit of his southern parishes wrote on 28 May 1884:
'Influenza Kenai, Ninilchik, Seldovia, Alexandrovsky [English Bay], nearly all children up to 2 years of age were swept away. At the same time this region suffered from innundation caused by the eruption of Chernabura volcano, which is about 60 miles across the straight from Alexandrovsky. The innundation so frightened natives of Alexandrovsky that they moved their huts to higher ground in one night [Russian Orthodox church records, Diocese of Alaska, Library of Congress, microfilm copy of Reel 1, Box 400, University of Alaska Anchorage Archives].'
"This report is consistent with Davidson's and Dall's that the largest sea wave was high enough to 'deluge the houses' at English Bay.
"The volcano evidently continued in eruption at least intermittently for weeks or months. Some time after 10 November 1883 (when in schooner Kodiak Captains Cullie and Sands approached Augustine Island), Davidson (1884) includes in his account:
'The condition of the Island of Augustin or Chenaboura, according to the latest accounts, is this: --
'At night, from a distance of fifty or sixty miles, flames can be seen issuing from the summit of the volcano; and in the day-time vast volumes of smoke roll from it.'
"Another entry in the Kenai Mission record by Heiromonk Nikita on 27 May 1885 reads:
'Earthquakes still quite frequent here [at Kenai?] and Chernabura is still smoking.'
"Davidson's (1884) account includes several obvious errors of observation or interpretation, including a Capt. Cullie description rendered into a fanciful figure (Davidson, 1884, p. 188). A chagrined Davidson later tried to rectify this in a letter (unpublished) dated 5 November 1884 addressed to Prof. J.E. Hilgard, Superintendent of the USCGS. One of Davidson's late-1883 sources, Capt. Cullie of the Alaska Commercial Company at English Bay, had sailed past Augustine Island in June 1884. As reported in Davidson's November letter, Capt. Cullie saw from the north that:
'. . . from the summit a great slide of the mountain over half a mile broad had taken place towards the rocky boat harbor on the northnorthwestward.11 It appeared as if there had been a great sinking of the rocks under the summit leaving a face of wall overlooking the slide. Down this had poured the lava [sic] and erupted material to the base of the mountain and had pushed into the boat harbor and filled it up. In the upper part of lava [sic] outflow was issuing great volumes of white smoke . . .'
"A later record about Augustine's preeruption 'boat harbor' exists in the field notes of USGS geologist J.A. Spurr (USGS archives):
'Oct. 17 (1898) Trader says here at Katmai that eighteen years ago [sic] three families from Kodiak went with families and baidarkas to St. Augustine Island to spend the winter. Built barabaras on the shore of a bay. The mountain began to shake continually and finally they took their families off, while they stayed on themselves. Finally the mountain began to shake so violently that they put all their effects in their bairdarkas and started on a stormy day. Scarcely were they at the mouth of the bay when an explosion occurred, ashes, boulders, and pumice began pouring down and the barabaras were buried and the bay filled up with debris. At the same time there were many tidal waves, so the natives nearly perished with fright, yet finally escaped.'
"Becker's (1898) published account mostly reiterates information in Davidson (1884) and Dall (1884) about events of 6-7 October 1883 but includes a few details from a climb in 1895 by Becker and his assistant Purington nearly to the summit and to the new dome (Becker, 1898, p. 29):
'. . . Steam escaped from countless crevices, most of them on the inner cone [that is, a new dome] . . . . Masses were from time to time detached, rolling down to the bottom of the deep moat which separates the outer crater from the inner cone . . . . The inner cone [is] nearly as high as the outer rim.'"
Waitt and Beget (2009) describe the Burr Point debris-avalanche deposit that formed during this eruption, evidence for a tsunami, the 1883 pyroclastic flow and surge deposits, and the 1883 lava dome in detail.
Simkin and others (1995) also calculate the volume of the lava flow plus the volume of the lava dome to be 0.13 cubic km. Simkin and Siebert (2002- ) give an estimate of 0.13 +/- 0.04 cubic km for lava from this eruption, and 0.51 +/- 0.5 cubic km as a tephra volume.

Barrett (1978) notes that in 1944 a small lava dome was discovered forming in the crater.

From Shackelford (1978): "In the morning of 22 January Augustine began a period of major activity from a new vent located at the contact of the 1935 and 1964 domes. The first major eruption began at 0740 AST on 23 January. On that date there were at least 8 major eruptions, one was at 1618 AST. An additional 4 major explosive outbreaks took place on 24-25 January. The eruption clouds pierced the tropopause, reaching heights + 10,000 m to 14,000 m a.s.l. Ash falls took place at Iliamna, Homer, Seldovia, and Anchorage (1.5mm). The January eruptions explosively removed most of the summit 1964 dome, forming a crater breached to the N.
"* * * The explosive activity was accompanied by major pyroclastic flows, and mudflows and lahars. The January glowing avalanches spread radially over the island, reaching the sea on the S, NE, and NW flanks. The Burr Point Research Station (NW tip of island) was severely damaged by one or more avalanches, although protected by a ridge, as a result of a back eddy in the clouds. Several days afterwards, temperatures in the pyroclastic flow deposit exceeded 400 degrees C at a depth of 2.7 (deposit is on the NE slope). There was an active fumarole field at the distal end of the deposit. Augustine was relatively quiet from 26 January to 5 February.
"The second cycle of eruptions began with the renewal of major activity at 0443 on 6 February, resulting in falls of ash and mud along the Kenai Peninsula. A strong eruption at 1230 on the 6th produced a cloud that rose to a height of 8-9 km. A blizzard-like ash fall at Homer on the 6th was the heaviest of the entire eruption, prohibiting vehicular traffic because of the induced darkness at 1800. Eruptions generally ended on the 15th, producing eruption plumes that usually rose to heights of 3-4, 5 km. Again, there was production of major pyroclastic flows which followed the same paths as those of January. The January flows had formed a new beach on the NE part of the island, and a further extension of this beach resulted from the glowing avalanches of February * * * Activity on the 16th consisted of occasional steam explosions. On the 18th there were a few ash-laden puffs rising from Augustine. Observations on that date showed that a new tholoid had formed in the new crater, probably on the 12th and 13th which was a period of continuous harmonic tremor. The new dome was found to be about 260 m above its base. From 19 February to April another quiet period ensued, although there were some block and ash flows off of the new dome beginning in late February. There was some earthquake swarm activity on 15 to 25 March.
"The third and last cycle took place in April. In the early part of the month explosion earthquakes began to be recorded on the new seismic array. The number of eruptions as follows: 6-12 eruptions per day during 6-9 April, 1 eruption per hour on 10-11 April, almost continuous intense eruptions during 12-18 April, 12 eruptions per day on 18-22 April. Eruptive behavior returned to low levels on the 23rd. Since 24 April there have been no further eruptions, just quiet degassing from the new dome, with some spectacular plumes reported. The April explosive activity was accompanied by block and ash flows shed off the new dome, which underwent a period of renewed growth in April."
David Johnston (1978) calculates that "roughly 0.17 cubic km of rock was erupted in 1976, of which about 27% was erupted in January, 59% in February, and 14% in April. Fifty-three percent of the volume is in pyroclastic flow deposits, 38% in the lava dome, and 8% in ash-fall and pyroclastic surge deposits. Ejecta erupted in January include approximately 10% andesite scoria, 50% dacite pumice, and 40% hybrid and banded pumices."
Kienle and Swanson (1985) have slightly different volume estimates for this eruption: "* * * the estimated bulk volume of the ejecta from the 1976 eruption is about 0.4 cubic km, of which 0.06 cubic km are flows on the island itself and the rest [0.339 cubic km] is tephra. We arrived at this estimate by digitizing the the pre- and post-eruption topography of the sector most affected by debris flow activity, the northeast sector of the Island (see Figure 31 in original text) and by using conservative estimates of the total thickness of tephra accumulation for the area that was affected by ash falls (See Figure 15 in original text)."

From Swanson and Kienle (1988): "Precursory seismic activity was first detected in July 1985, 8 months prior to the 1986 eruption. A sharp increase in seismicity in March 1986 led to speculation about a possible eruption (Kienle, 1986). A several-order-of-magnitude increase in seismic event counts on the morning of March 26 heralded the eruption that began on the morning of March 27. A short-term forecast of the eruption was made on the afternoon of March 26 (Kienle and others, 1986).
"The initial phase of the eruption involved explosive removal of a portion of the 1976 dome and formed a small (about 100 m in diameter) vent on the southwest flank of the dome (Miller and others, 1987; Yount and Miller, 1987). Numerous pyroclastic flows were observed during the 103 hours of this first eruptive phase, and eruption columns reached heights in excess of 12,000 m (Yount and others, 1987). Pyroclastic flows were directed through the breach in the north side of the crater and spread out on the lower flanks of the volcano. Some of these pyroclastic flows reached the sea to the west and east of Burr Point, and ash cloud surges continued for some distance offshore.
"Prevailing winds on March 27 and 28 were from the southwest and spread ash throughout Cook Inlet. Later on March 28, the winds shifted to the west and finally to the north on March 30 and 31. Ash was thus scattered over populated areas in Cook Inlet only during the early stages of the eruption, but the dust lingered in the air over Cook Inlet, including Anchorage, until March 31.
"Lava was extruded during the second eruptive phase from April 23 to 28. A short blocky lava flow issued from the base of the 1976 dome remnant. Pyroclastic flows descended from the growing dome, but none of them reached the sea.
"* * * A period of accelerated dome growth between August 30 and 31, 1986, resulted in an increase of pyroclastic flow activity. Flows moved down the north flank of the volcano for distances up to 2.2 km from the source (Kienle, 1986). Eruption clouds rose 1000 to 2000 m above the volcano during this episode. None of the pyroclastic flows reached the sea.
"High-silica, two-pyroxene andesite, similar to that produced in previous Mount St. Augustine eruptions was also erupted in 1986 (Swanson and others, 1986; Harris and others, 1987). Groundmass glass in the 1986 andesites is rhyolitic in composition, as in past eruptions, and this is one factor in the explosive character of the eruption. Distribution of eruptive products and volumes of material erupted in 1986 was also similar to other historic eruptions.
"Pyroclastic flow deposits were restricted to the north flank of the volcano, the result of funneling through the breach in the north side of the crater. Lahars composed of reworked air fall deposits form a circular pattern around the upper part of the cone. On the south flank, lahars descended to about 300 m above sea level.
"The new dome occupies the central part of the volcano and a small lava flow extends just a few hundred meters from the dome. A new 50-m-high spine was extruded during the August phase of renewed dome growth. Since then, a large section of the 1986 dome has collapsed and has formed a debris avalanche deposit on the upper northern slope of the volcano.
"Incandescent vents were discovered on August 28, 1987, at the southern base of the spine, with maximum fumarole temperature of 88 degrees C (R. Symonds, personal communication, 1987).
"A new topographic map of Augustine Island was prepared by North Pacific Aerial Surveys for the U.S. Geological Survey from aerial photography taken on September 9, 1986, using geodetic control points surveyed by University of Alaska and U.S. Geological Survey personnel on June 6, 1986 (J. Power, personal communication, 1986). The map shows that the 1986 dome had reached a height of 1252 m by September 9, 1986. Thus the dome gained about 26 m in elevation between 1976 and 1986. The highest point of the volcano is the south peak, which remained unchanged at 1252 m. More changes in dome height could have occurred since then, but the dome has not yet been resurveyed. The total expanded volume of the 1986 pyroclastic flow deposits on Augustine Island is estimated to be close to the 1976 pyroclastic flow volume of about 0.05 cubic km, but could be a little larger."
The April edition of the Scientific Event Alert Network Bulletin (v. 11, n. 04) gives an inflated material estimate of 0.11 cubic km for the March 31 pyroclastic flow, and an estimate volume for the dome (as of May 6) of 0.06 cubic km.

From Power and others (2006): The 2006 eruption of Augustine consisted of four phases defined by the character of unrest or eruptive activity, which are described below. These phases are the precursory (May 2005 to 11 January 2006), the explosive (11 to 28 January), the continuous (28 January to 2 February), and the effusive (2 February to late March).
"The precursory phase began as a steady increase in microearthquakes beneath the volcano, ranging from one to two per day in May 2005 to 15 per day in mid-December [see Figure 3 in original text]. In July 2005, geodetic baselines began to lengthen, indicative of pressurization at sea level centered beneath the edifice (Cervelli and others, 2006). On 2 December 2005, seismometers began recording signals from small phreatic explosions; the largest signals occurred on 10, 12, and 15 December. An overflight on 12 December revealed vigorous steaming, a new vent on the summit's southeastern side, and a dusting of ash on the volcano's southern flanks. The ash was a mix of weathered and glassy particles; the latter appear to be remobilized 1986 tephra. An explosion on 15 December disabled the telemetery for the two highest seismic stations [see figure 2 in original text].
"Augustine then entered an explosive phase, which lasted from 11-28 January 2006. A strong swarm of volcano-tectonic (VT) earthquakes began at 0030 UTC on 11 January, culminating in explosive eruptions at 1344 and 1412 UTC. These explosions produced ash plumes, reported by the U.S. National Weather Service (NWS) to have reached heights greater than nine kilometers above sea level (asl), which moved slowly to the north and northeast. Ash sampled on 12 January was primarily dense or weathered fragments, suggesting little juvenile magma. Over the next 36 hours, several sequences of small, regularly spaced VT earthquakes, many with identical waveforms, occurred at rates as high as three to four per minute. Similar earthquakes, referred to as clones or drumbeats, have been associated at other volcanoes with the emplacement of lava domes (Dzurisin and others, 2005).
"Monitoring instruments also recorded six powerful explosions that occurred between 1324 UTC on 13 January and 0914 UTC on 14 January [see figure 3 in original text]. The first explosion destroyed the seismometer and CGPS high on the volcano's northeastern flank [see figure 2 in original text]. Plumes reached altitudes of 14 kilometers asl and deposited traces of ash on southern Kenai Peninsula communities. Ash from these eruptions was more heterogeneous and contained dense particles as well as fresh glass shards, indicating the eruption of new magma. Satellite imagery tracked these plumes as they moved eastward and disrupted commercial airline traffic to and from Alaska.
"A 16 January overflight revealed a small, new lava dome at the summit. An explosive eruption at 1658 UTC on 17 January sent ash to 13 kilometers asl that moved westward. The eruption left a 20- to 30-meter-diameter crater in the new dome and produced ballistic fields on the volcano's western flanks. Data transmission from the west flank CGPS station stopped coincident with this explosion [see figure 2 in original text]. Additionally, the eruptions of 13-17 January generated pumiceous pyroclastic flows, snow avalanches, and lahars that moved down the volcano's flanks [see figure 2 in original text].
"The volcano then entered a period of more continuous eruptive activity that began at 0534 UTC on 28 January and that lasted until 2 February. The phase began with four explosive eruptions that generated ash plumes to heights of nine kilometers asl [ see figure 3 in original text]. Ash moved southward and fell in trace amounts on Kodiak Island. These explosions generated substantial pumiceous pyroclastic, block, and ash flows that destroyed seismic and CGPS stations on the west and north flanks of the volcano [see figure 2 on original text]. Destruction of these seismometers compromised AVO's ability to assign reliable hypocentral depths to earthquakes.
"Data from the remaining CGPS stations indicated that the volcano reversed its long inflationary trend (during which accumulating magma caused a swelling of the volcano's surface) and began a sharp deflation that continued until 10 February [see figure 3 in original text]. Modeling suggests the locus of deflation, which results from the removal of magma, was much deeper (~10 kilometers) than the precursory signal. On 29 January, the seismic network began to detect numerous block and ash flows - generated by small failures of the growing lava dome - cascading down the volcanos northern flanks [see figure 2 in original text].
"Augustine then entered an effusive phase, which lasted through late March. From 2 February through 6 March, block and ash flow signals continued to dominate the seismic record. Geodetic data showed inflation from 10 February until 1 March, when the volcano again reversed and entered an 11-day period of deflation [see figure 3 in original text]. On 7 March, seismic activity again shifted to small, mostly identical repetitious earthquakes. These events increased in rate and size, forming a continuous signal early on 8 March that lasted until 14 March. They then began a slow decline and disappeared by 16 March. Lava extrusion at the summit increased markedly in association with these repetitive earthquakes, and two blocky lava flows moved down the north and northeastern flanks [see figures 1 and 2 in original text]. Observations indicate that the effusion of lava stopped in late March. The volcano entered a final period of inflation between 12 and 31 March. The estimated volume of effusively erupted material is currently 30 million cubic meters."

McGimsey and others (2011) report that throughout 2007, continued cooling from the 2005-2006 eruption, steam plumes, and anomalous seismicity were observed at Augustine.

From Dixon and others, 2017: "Minor unrest occurred at Augustine Volcano in 2015 in the form of visible vapor plumes and rockfalls. In collaboration with Cascade Volcano Observatory (CVO), in June AVO installed a Multiple component Gas Analyzer System (MultiGAS) instrument at the summit of Augustine, designed to measure carbon dioxide (CO2), sulfur dioxide (SO2), and hydrogen sulfide (H2S). The Aviation Color Code/Volcano Alert Level remained GREEN/NORMAL throughout the year.
"Augustine has active fumaroles that often are visible under favorable atmospheric conditions. A gas measuring/sampling flight on April 3 detected low levels of water (H2O), CO2, SO2, and H2S, indicating that Augustine continues to degas at a low rate. The typical vapor plume at Augustine was often visible in web camera images during 2015, and was noted in satellite daily checks on January 25 and July 9. AVO received a PIREP of steam at Augustine on July 9.
"Twenty-two instances of rockfalls occurred at Augustine in 2015 as identified by emergent signals recorded on Augustine seismograph stations: this was twice the number of rockfalls reported in 2014. These rockfalls were concentrated during the months of June, July, August, and October. Rockfall signals at Augustine typically have an emergent onset and appear first at summit stations AUP and AUSS (fig. 5 [original text]).
"On June 12 and 13, AVO and CVO scientists installed a new, permanent MultiGAS/ seismograph station near the summit of Augustine. The MultiGAS instrument (fig.6) was designed and built at CVO, and includes sensors to intermittently measure CO2 and H2S. Data from these sensors are transmitted to AVO in near real time. A broadband seismograph station was installed near the MultiGas station at this time. Two months later another broadband seismograph station was added to the Augustine seismograph network."