Fierstein and Hildreth (2001) provide information about the magitude of the 1912 eruption at Novarupta and Katmai: "The world's largest volcanic eruption of the 20th century broke out at Novarupta [see fig. 1 in original text] in June 1912, filling with hot ash what came to be called the Valley of Ten Thousand Smokes and spreading downwind more fallout than all other historical Alaskan eruptions combined. Although almost all the magma vented at Novarupta, most of it had been stored beneath Mount Katmai 10 km away, which collapsed during the eruption. Airborne ash from the 3-day event blanketed all of southern Alaska, and its gritty fallout was reported as far away as Dawson, Ketchikan, and Puget Sound [see fig. 21 in original text]. Volcanic dust and sulfurous aerosol were detected within days over Wisconsin and Virginia; within 2 weeks over California, Europe, and North Africa; and in latter-day ice cores recently drilled on the Greenland ice cap."
Schaaf (2004) contains excerpts and summaries of eyewitness accounts of the eruption; a copy of this publication is available online at www.nps.gov/articles/aps-v11-i…. Detailed, firsthand narratives of the events as experienced at Kodiak are given in Perry, 1914, and Erskine, 1962.
Hildreth and Fierstein also published a free download tome of information about this eruption: pubs.usgs.gov/pp/1791/
From Fierstein and others (1998): "On the afternoon of June 6, 1912, an ominous cloud rose into the sky above Mount Katmai on the Alaska Peninsula. The cloud quickly reached an altitude of 20 miles, and within 4 hours, ash from a huge volcanic eruption began to fall on the village of Kodiak, 100 miles to the southeast. By the end of the eruption on June 9th, the ash cloud, now thousands of miles across, shrouded southern Alaska and western Canada, and sulfurous ash was falling on Vancouver, British Columbia, and Seattle, Washington. The next day the cloud passed over Virginia, and by June 17th it reached Algeria in Africa.
"During the 3 days of the eruption, darkness and suffocating conditions caused by falling ash and sulfur dioxide gas immobilized the population of Kodiak. Sore eyes and respiratory distress were rampant, and water became undrinkable. Radio communications were totally disrupted, and with visibility near zero, ships couldn't dock. Roofs in Kodiak collapsed under the weight of more than a foot of ash, buildings were wrecked by ash avalanches that rushed down from nearby hillslopes, and other structures burned after being struck by lightning from the ash cloud.
"Similar conditions prevailed elsewhere in southern Alaska, and several villages were abandoned forever. Animal and plant life was decimated by ash and acid rain from the eruption. Bears and other large animals were blinded by ash and starved when large numbers of the plants and small animals they lived on were wiped out. Millions of dead birds that had been blinded and coated by volcanic ash littered the ground. Aquatic organisms, such as mussels, insect larvae, and kelp, as well as the fish that fed upon them, perished in ash-choked shallow water. Alaska's salmon-fishing industry was devastated, especially from 1915 to 1919, because of the starvation and failure of many adult fish to spawn in ash-choked streams.
"In 1916, a National Geographic Society expedition led by Robert Griggs visited Mount Katmai and found a 2-mile-wide crater where its summit had been before 1912. Nearby, the expedition discovered a newly formed lava dome they called 'Novarupta' and huge flows of volcanic ash filling what they named the 'Valley of Ten Thousand Smokes' for the numerous plumes of steam rising from the still hot ground. Griggs' descriptions of these spectacular features helped persuade President Woodrow Wilson to create Katmai National Monument (now National Park) in 1918.
"In the 1950's, volcanologists discovered that the 1912 eruption was actually from Novarupta, not Mount Katmai. Novarupta's eruption had removed so much molten rock (magma) from beneath Mount Katmai that it caused a cubic mile of Katmai's summit to collapse."
Hildreth (1983) gives the following detailed description of the events of the eruption: "Because there were no geophysical instruments in Alaska, no scientfic observers in the district, and no eyewitnesses with a view of the VTTS [Valley of Ten Thousand Smokes], most reports of seismic, acoustic, and eruptive phenomena were not necessarily very accurate, chronologically or descriptively. The most reliable data are the visual observations from aboard the steamer Dora and the record of tephra falls at Kodiak [see figs. 1, 4, in original text] (Martin, 1913; Griggs, 1922). Martin visited Kodiak, Uyak, Katmai village, and Cold Bay [see fig. 1 in original text] in August of 1912 and gathered what accounts he could from residents of the district, but he did not venture inland to the volcanoes nor was he able to interview anyone from the two bands of native hunter-fishermen said to have been within 30 and 40 km, respectively, north and south of Novarupta at the time of the initial outburst. Reconstructions of the eruptive sequence by Griggs (1922) and Fenner (1923, 1925, 1950) are heavily inferential, overinterpretive both of Martin's data and of latter-day interviews with people said to have been at Savonoski when the eruption began (see below), and suffer badly from the incorrect assumption that much of the tephra had come from Mt. Katmai. The following is a critical reappraisal of what appear to be the facts, as assembled largely by G.C. Martin (1913; and unpublished USGS field notes); all times cited are adjusted to Alaskan local time.
"Earthquakes were reported to have been felt at Katmai village (30 km SSE of Novarupta) as early as the evening of 31 May, and severe shocks were felt at Uyak, Kanatak, and Nushugak (200 km WNW) on 4 and 5 June. On the morning of 6 June, explosions were heard at Nushugak and at Seldovia (240 km ENE) but there were no reports of accompanying seismicity or ash clouds. The same morning the Dora left Uyak at 0845 and steamed north-eastward up Shelikof Strait, the Katmai-group volcanoes in full view with a 'strong westerly breeze and fine clear weather,' but no one aboard noticed a tephra column until 1300 (when the vessel was ~88 km southeast of Novarupta). That column was clearly Plinian and, as shown below by the stratigraphic data, it was predominantly rhyolitic; the cloud overtook the Dora by 1500 and began dropping ash at Kodiak (170 km ESE) [see figs. 1, 4, in original text] by 1700.
"Separate interviews with two individuals said to have been in or near Savonoski (30 km N) on the morning of 6 June were conducted in 1918 (Griggs, 1922, p. 17) and in 1923 (Fenner, 1925, p. 216); these have been interpreted to suggest that the ash flow in the VTTS began in the morning several hours prior to the first high tephra column. This is quite unlikely in view of: (1) the record of the Dora; (2) the fact that the basal tephra layer in the VTTS, the distinctively rhyolitic Layer A, does not occur atop the ash-flow deposit; and (3) the common association of pumiceous pyroclastic flows with the collapse of vertical eruption columns. Preliminary eruptive activity at Novarupta on the morning of 6 June is quite reasonable and may be the best explanation of the noise and dust reported that morning at Savonoski and the explosions heard at Nushugak and Seldovia; but a major eruption column and a rhyolitic ash flow several km^3 in volume are certainly excluded prior to 1300.
"Major shocks that punctuated virtually continuous seismic activity were reported locally at ~1300 and ~2300 on 6 June and ~2240 on 7 June. These times are not necessarily very accurate. The first instrumentally recorded teleseism (at Seattle) is reported to have arrived at 1241 on 6 June (Fenner, 1925). Harvard, Ottawa, and several Eurasian stations recorded many teleseisms originating in southwest Alaska between 1805 on 6 June and ~2100 on 11 June. One of these near midnight on 6/7 June has been estimated at magnitude 6.4 and another at 0606 on 10 June at magnitude 7.0 (Coffman and von Hake, 1973). Earthquakes following the main phases of the eruption were felt at Cold Bay (60 km SSW) on 50 of the 70 days through mid-August (Fenner, 1925).
"A great explosion, accompanied by an earthquake felt at Cold Bay ~1300 on 6 June (Martin, 1913), was audible throughout the region and close in time to the first recorded teleseism and to the first sighting of tephra by the Dora. Another blast at ~1500 on 6 June, for which no accompanying earthquake was noted, may have been the most severe outburst of all, being heard for hundreds of kilometers (Martin, 1913). Martin suggested, but did not cite any evidence for, explosions synchronous with the large earthquakes felt nearby at ~2300 on 6 June and 2240 on 7 June. There were, however, reports of loud noises between midnight and 0200 on 8 June, at Katanak (95 km SW) and at Cordova (590 km ENE) (Martin, 1913; Fenner, 1925). Explosions continued to be heard, some as far away as Juneau (1200 km) until 10 June, though how many of the noises may have been thunder is impossible to assess.
"Major tephra eruptions, first noted by the Dora at 1300 on 6 June, continued to fall heavily on downwind settlements nearby until 9 June. The principal sector of dispersal was southeastward [see fig. 1 in original text], and the most distant positive record of ashfall was in Puget Sound (2400 km SE); atmospheric effects were worldwide (Griggs, 1922; Volz, 1975). In the main downwind direction at Kodiak (170 km ESE) there were three discrete periods of ashfall [see fig. 4 in original text]: (1) 1700 6 June until 0910 7 June; (2) ~1200 7 June until 1430 8 June; and (3) during the night of 8/9 June. The 9th of June dawned clear, and no further ash-falls were recorded on Kodiak Island. A major vapor plume and, possibly, sporadic ashfalls close to the source lasted all summer (Martin, 1913; Griggs, 1922; Fenner, 1925). Timing of the emplacement of the Novarupta dome is poorly known; its extrusion followed the last major tephra fall and was complete at the time of discovery on 31 July 1916.
"Details of correlation between audible explosions, tephra falls, and seismic events are not well known. Martin (1913) is the principal source, but his article has been misread and overinterpreted and ensuing errors propagated in successive publications. The seismicity does not correlate very well with eruptive events, and indeed there need be no correspondence (e.g. Filson and others, 1973; Nairn and others, 1976; Yokoyama and others, 1981). Much of the seismic activity seems more likely to have been related to fitful subsidence of Katmai and Novarupta calderas.
"At the onset of eruption, no one is known to have had a view of the VTTS (much less the Novarupta area itself), and only the party of native fishermen then southwest of Katmai village en route to Cold Bay may have been in a position to see Mt. Katmai. The Savonoski interviews (above) smack of ex post facto embellishment, although Martin (1913, p. 147) accepted a third hand report in 1912 that the villagers there may have seen Mt. Katmai after its collapse, but before 9 June. It is not clear where they might have had such a view, because, even notwithstanding the ash clouds, Mt. Katmai is not visible from Savonoski or along their escape route down the lake to Naknek [see fig. 1 in original text]. Martin, Griggs, and Fenner accepted such reports to mean that Mt. Katmai had lost its top by the afternoon of 6 June. This may be true, but it is not clear how Mt. Katmai could have been seen at all during the eruptive interval at Novarupta or what meaning should be attached to such expressions as 'blown off' or 'blown up.' No definitive geologic evidence has been found to fix the timing of Mt. Katmai's collapse, but it may be a reasonable inference that in addition to the syneruptive earthquakes, much of the summer-long seismicity can be attributed to such collapse, as well as to tectonic adjustments over a somewhat wider area, or even to dome emplacement at Novarupta."
Hildreth (1983) also reports that "pumice in the intial fall unit (A) is 100% rhyolite, but fall units atop the ash flow are >98% datcite; black andesitic scoria is common only in the ash flows and in near-vent air-fall tephra." He also states: The Novarupta lava dome is "diameter 380 m, its hieight ~65 m, and the intermediate (mostly dacite) lava interbanded with the rhyolite consitutes no more than 5% of the exposure; most of the conspicuous banding reflects textural variation in the rhyolite."
Fierstein and Hildreth (2001) estimate that the Novarupta eruption of 1912 ejected "at least 17 cubic km of fall deposits and about 11 cubic km of ash-flow tuff (ignimbrite) * * * emplaced in about 60 hours, representing a magma volume of about 13 cubic km (Fierstein and Hildreth, 1992). Hildreth (1987) estimates the volume of the Novarupta lava dome to be 0.005 cubic km.

From Cameron and others, 2017: "Resuspension and transport of fine-grained volcanic ash from the Katmai National Park and Preserve region of Alaska frequently have been observed and documented for decades (Hadley and others, 2004; McGimsey and others, 2005), and five episodes of resuspended ash were documented in 2014. The 1912 eruption of Novarupta deposited large quantities of ash in valleys of the Katmai area, and the landscape remains desolate and largely vegetation-free, even more than a century later. During times of no snow and strong northwesterly winds, the ash can be resuspended and transported southeast across Shelikof Strait, Kodiak Island, and the Gulf of Alaska. These events commonly are identified by the presence of ash blowing from the Katmai area, often detected in satellite imagery, coupled with existing high winds and a lack of other volcanic signals (no thermal anomalies, no increased seismicity).
"On May 19, flights to Karluk on Kodiak Island were delayed because of weather conditions and a visible plume of resuspended ash originating from the Katmai area. The ash was weakly visible in satellite imagery, and strong northwesterly winds were blowing from the Katmai area towards the southeast. The National Weather Service Alaska Aviation Weather Unit (NWS AAWU) issued a Special Weather Statement. The NWS AAWU also issued SIGnificant METeorological information statements (SIGMETs) for resuspended Katmai ash due to strong winds on September 29 and October 5, when ash again was visible in satellite imagery blowing toward Kodiak Island. During the October 5 event, a citizen of Kodiak reported ash to AVO using via AVO’s "Is Ash Falling" system. Ash reached an altitude as high as 1,200-1,800 m (4,000-6,000 ft) ASL during the October 5 event.
On October 14, strong winds in the Katmai area once again picked up loose 1912 volcanic ash and carried it east over Shelikof Strait and Kodiak Island. The National Weather Service estimated the top of the cloud at an altitude of 1,200 m (4,000 ft) ASL. The NWS issued a Special Weather Statement, and AVO received a report of hazy conditions and trace ashfall (less than 1/32 in. deep) at Karluk on the southwestern side of Kodiak Island through AVO’s "Is Ash Falling" online ash reporting system. Federal Aviation Administration (FAA) Web camera images in Karluk also showed hazy conditions. AVO mentioned the resuspended ash event in the Friday, October 17, weekly update.
"The last ash resuspension event of 2014 occurred on Thursday, October 23, when strong winds resuspended 1912 volcanic ash and carried it southeast over Shelikof Strait, Kodiak Island, and the Gulf of Alaska. The ash was detected in satellite imagery, and the NWS issued Special Weather Statements, SIGMETs, and a Volcanic Ash Advisory. AVO
included the ash resuspension event in its Friday, October 24, weekly update."

From Dixon and others, 2017: "High winds entrained and resuspended ash from Novarupta-Katmai 1912 on March 11, 2015, continuing into March 12, 2015. Alaska Airlines and Ravn Alaska cancelled flights into and out of Kodiak, due to high winds and ash. The ash was visible in satellite imagery, and strong winds were blowing from the Katmai area toward the southeast (fig. 7 [original text]). The National Weather Service Alaska Aviation Weather Unit (NWS AAWU) issued a Special Weather Statement.
"Four episodes of resuspended ash were observed during August through October. A multi-day ash resuspension event began on August 28, 2015, and continued through August 31, 2015. On August 30, the NWS issued a SIGnificant METeorological (SIGMET) information statement, and AVO mentioned the resuspended ash in its August 28 weekly update and issued a separate information statement on August 31. The ash was weakly visible in satellite imagery. Two ash resuspension events occurred in September-on
September23, with ash confined to altitudes less than 1,500 m (5,000ft) ASL, and another on September 29-30.
Residents of Kodiak reported a fall of fine ash on the night of September 29-30, mixed with sleet and snow. AVO issued information statements on both occasions. The final ash resuspension event of 2015 occurred on October 29-30, when strong winds in the Katmai area again entrained loose 1912 volcanic ash and carried it east over Shelikof Strait and Kodiak Island. AVO again issued an information statement regarding the event."

From Dixon and others (2020): "On June 4, 2017, a National Oceanic and Atmospheric Administration (NOAA) and National Environmental Satellite, Data, and Information Service ash alert reported a possible resuspension event over the Valley of Ten Thousand Smokes (fig. 9). Atypical, easterly winds carried resuspended ash away from population centers so that an AVO Information Statement was not issued. AVO alerted the NWS Alaska Aviation Weather Unit * * * ,
"Two ash resuspension events were detected in November, and the first was identified by a NOAA and Cooperative Institute for Meteorological Satellite Studies ash alert. On November 10, strong northwest winds over the Valley of Ten Thousand Smokes resuspended volcanic ash into a visible cloud and transported it eastward across Shelikof Strait and over Kodiak Island, where it was detected by the AVO particulate monitors at Larson Bay on the west coast of Kodiak Island. A similar sensor in the city of Kodiak, Alaska, on the east coast of Kodiak Island did not record any ash for this episode. AVO issued an Information Statement corroborating the hazard notifications issued by the NWS. By the evening of November 10, the resuspension event started to wane despite the surface winds continuing with gusts up to 20 meters per second (66 feet per second). A similar resuspension event occurred on November 13. The resuspended ash cloud extended 120 km (72 mi) to the southeast over the south end of Kodiak Island where no particulate monitors were installed. (fig. 10). AVO issued another Information Statement after the detection of this resuspension event."

From Orr and others, 2024: "On August 28, 2021, strong winds picked up loose volcanic ash from the Mount Katmai (Novarupta) region and carried it southeastward toward Kodiak Island. The National Weather Service (NWS) had forecasted this event a few days prior, and when it occurred, the NWS Alaska Aviation Weather Unit (AAWU) reported cloud heights as much as ~6,000 ft (~1,800 m) ASL, issuing a significant meteorological information statement (SIGMET) for aviators. AVO also issued an Information Statement.
"The following month, strong winds again generated a cloud of resuspended ash that drifted over Kodiak Island. This event, like the one a month prior, was anticipated by the NWS a few days in advance. The drifting ash cloud appeared clearly in satellite data for ~24 hours, starting in the afternoon of September 20. AAWU issued a SIGMET reporting ash at altitudes as high as ~8,000 ft (~2,400 m) ASL; AVO correspondingly issued an Information Statement. Trace ash fall was reported in the City of Kodiak, Alaska, and owing to the forecast of this event, a local observer was able to sample the ash fall and send it to AVO.
"The ash resuspension had ceased for only two days when, beginning late in the afternoon on September 23, winds again picked up loose ash. This ash cloud drifted east across northern Kodiak Island at an apparently lower altitude (~5,000 ft [~1,500 m] ASL), though no ashfall was reported. This resuspension event also lasted ~24 hours, during which time AAWU issued a SIGMET and AVO issued an Information Statement.
"AVO observed the next minor cloud of resuspended ash in satellite views on September 26. This cloud drifted southeastward toward the middle of Shelikof Strait, never reaching Kodiak Island. No Information Statements were issued for this minor event.
"Before dawn on October 2, strong winds near Mount Katmai once again picked up loose volcanic ash and carried it southeastward toward Kodiak Island. As with most previous resuspension events at Mount Katmai in 2021, the NWS had forecasted the event a few days prior. AAWU issued a SIGMET and the NWS Forecast Office issued a Marine Weather Statement. AVO issued an Information Statement reporting ash clouds that reached altitudes of ~6,000 ft (~1,800 m) ASL. Meteorological clouds obscured satellite observations the next day, but the SIGMET remained in place for ~24 hours owing to the likelihood of continued ash resuspension.
"Starting on the morning of November 17, another cloud of resuspended ash appeared clearly in satellite data. Most of the typical source region for resuspended ash at Mount Katmai was covered in snow at the time, so this event’s ash source was apparently confined to valleys on the north side of Shelikof Strait, in the vicinity of Mount Katmai. AAWU issued a SIGMET reporting a cloud altitude as high as ~7,000 ft (~2,100 m) ASL; AVO correspondingly issued an Information Statement. Resuspended ash was visible in satellite data until about midnight, although reports of resuspended ash from the City of Kodiak continued into the following day. Residents in Kodiak collected trace ashfall.
"The last resuspension event in the Mount Katmai region in 2021 occurred on November 25. AAWU issued a SIGMET reporting a cloud that drifted over Kodiak Island at an altitude as high as ~5,000 ft (~1,500 m) ASL. The NWS Forecast Office issued a Marine Weather Statement and AVO issued an Information Statement."