Geological Survey Circular 318 Eruption of Trident Volcano — Katmai National Monument, Alaska — February-June, 1953

Lieutenant Commander Frank Chase, flying eastward at 15,000 feet altitude over Port Heiden on the Alaskan Peninsula one calm Sunday afternoon was astonished to see a huge tower of smoke mushroom into the sky on the horizon almost 150 miles away. The time was about 4:00 p. m. (A. s. t.), February 15, 1953. The center of activity was determined to be somewhere in the vicinity of Mount Katmai in Katmai National Monument. The eruption cloud was estimated at the time to extend to about 30,000 feet, twice the altitude at which the plane was flying. A photograph taken by a crew member of Commander Chase's plane from just south of Cape Kekurnoi (35 miles south-southwest of Katmai) corroborates this estimate. Only 1 eruption cloud is visible in this photograph and, although the picture is not clear enough for positive identification, subsequent observations indicated that this smoke column was arising from Trident Volcano, an old eroded volcano with no previous historical record of eruption, located 4 miles west-southwest of Mount Katmai.

The initial explosion was also reported by the office of Northern Consolidated Airlines in King Salmon (on the north side of the Alaskan Peninsula) about 75 miles northwest of the eruption. An Associated Press release of February 15 states that "a unidentified Air Force pilot flying over the area 50 minutes after the eruption saw smoke and cinders had shot into the air to a height of 30,000 feet." Because of an unfavorable location behind mountains no one in Kodiak village or on Kodiak Naval Station (100 miles southeast of the eruption) could observe the initial smoke column.

When Mr. Chase landed at Kodiak Naval Station he reported his observations to Rear Admiral John Perry, Commander Alaskan Sea Frontier and Commandant 17th Naval District. Admiral Perry ordered Navy patrol planes to maintain surveillance on the volcano in event of increased activity that might endanger the lives of civilian and military personnel on the Alaska Peninsula and Kodiak Island. That same evening, Sunday, February 15, one Navy plane was dispatched to the scene of the eruption. By then, however, fog and smoke had covered the area, and nothing could be seen. Early Monday morning, February 16, two Navy planes returned to Katmai National Monument. Frank O. Brink was in charge of the photo crew in one of these planes piloted by Lt. Comdr. George H. Webster. The following Navy dispatch describes the first flight: "***Took off at dawn 700 AM. While enroute noticed thick smoke layer to left stretching over 100 miles. Valleys and mountains far as eye could see covered with ash. Difficult to pinpoint volcano because of cloud layer***LCDR Webster said too dangerous to get closer than 25 miles***840 AM Alaska standard time a navy crew of Grumman Albatross from the Naval Station Kodiak sighted second eruption volcano in Katmai region Alaska Peninsula***Huge ball cloud seen 20 degrees and 25 miles left of plane's heading. Cloud rose above 7,000 ft cloud layer with tremendous spread. Like giant mushroom just let go as plane arrived in area. Perfect imitation atom bomb explosion. 850 AM cloud mushroomed to 30,000 feet. Top fanned out diameter 10 miles. 855 AM top spread like sunflower to diameter 25 miles at height of 35, 000 feet." In later conversations, Mr. Brink declared that this eruption cloud was light gray and, hence, presumably was a steam explosion that carried but little ash. Movies indicate that above the clouds there was only a single mushroom smoke cloud, light gray in color.

At about the same time Lt. Comdr. Glen Thompson of the U. S. Coast Guard was also patrolling the area in a Coast Guard amphibian plane. Mr. Thompson was considerably lower than the U. S. Navy planes and also closer to the erupting vents. He flew beneath the cloud layer that obscured the ground from the higher planes, and taking a bearing on Mount Martin, flew northeast parallel to the chain of mountains. Near Mageik volcano the air became so smoky that he was obliged to continue ahead on instruments and did not relocate his position until he saw the emerald-green waters of the crater lake on Katmai volcano below him. As the smoke seemed to be thickest in the vicinity of Knife Peak Volcano, Mr. Thompson presumed this to be the erupting volcano. The identification of the eruptive center as Knife Peak was definitely mistaken, but the knowledge that there was thick smoke in the Trident-Mount Mageik area and none in the Katmai and Mount Martin areas was valuable information about the volcanic activity at that time. Movies, taken by a crew member on this run, show many scenes of smoke, fog, and steam, but the only land feature that can be definitely identified is Mount Martin, with its usual steam plume 500 feet high.

A summarizing Navy dispatch contains the following statement: "Observers on the second plane to visit the area Monday [February 16] reported that a second column of smoke and possibly a third was seen rising approximately 10 miles southwest of Katmai Volcano." This observation, if correct, would imply that both Trident and Mount Martin were erupting. Perhaps "steam" is meant instead of smoke, however, in which case the situation at the craters of Mageik and Mount Martin would be normal. No still pictures of the activity on February 16 are available.

Part of a Navy dispatch describing the observations of a flight on Tuesday (February 17) reads as follows: "Navy patrol crew from NAVSTA Kodiak today witnessed mass eruption of Katmai National Park. This was third and most spectacular display. 1055 AST plane flying 8000 ft. on 270 degrees course over Shelikof Strait sighted large black ball smoke about 25 miles 10 degrees left plane's heading. It rolled up like smoke from oil fire to 15,000 feet. Plane circled left of the eruption. In two minutes second cloud boiled up 8 miles NE first one. Moved closer, black smoke rose 30,000 feet. Streams of ash poured out of black smoke like rain falling from thunder cloud***smoke and debris from volcanoes appeared to move slowly to NW. Continued to fly within 5 to 6 miles of the erupting area. Smoke spread until it was difficult to see separate columns. [1] Smell of sulphurous volcanic smoke strong in plane. Pilot [Lt. James T. Ingram] pulled plane further away fearing ash might damage props and engine. Through an occasional break in the 8000 ft cloud layer below could see mountains and valleys covered with gray black ash." This much of this dispatch is well attested by the still photographs taken by Navy photographers as well as by Lieutenant Brink's 16 millimeter motion pictures of this phase of the eruption. It appears certain that there were at least 2 vents, Trident and 1 other, which were erupting smoke and ash on the third day of the activity. The identity of the other vent is not certain. Principal possibilities are Mount Martin and Mageik because these 2 volcanoes are almost continuous "steamers."

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¹The Navy dispatch of February 17 also contains the following statements: "1115 AST one after another new columns of smoke shot up is a line just like a chain of explosions. Ash started hitting plane *** more explosions took place in different areas. Counted between 6 and 8 separate columns of smoke." These statements require some clarification. From later conversations with Lieutenant Brisk and the other observers and after seeing Brink's film it appears that all of the above could have been caused by 1 vent sending separate puffs up through a cloud layer into a zone of moderate winds. Also, it might have been said that the plane started hitting ash rather than the above, as any ash at that altitude probably would have lost the original propulsive force of the gaseous explosion.

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One Navy photograph, dated February 17 and showing 2 smoke columns projecting above an under cast cloud layer, is labeled: "Two erupting clouds of steam and ash from Mount Katmai, in the foreground, and Mount Mageik, eight miles from Katmai***." If the estimate of an 8 mile distance between the columns is correct, the 2 erupting volcanoes must have been Trident and Mount Martin rather than Katmai and Mount Mageik. However, another photograph, also dated February 17 and supposedly taken on the same flight, shows Mount Martin placidly steaming as usual. The ash that fell from these 2 eruptions on February 17 was buried completely under fresh snow, so that the excellent observations from the air on February 18 contribute nothing to identify the second erupting volcano. It must have been either Mount Martin or Mount Mageik.

On Wednesday, February 18, the weather cleared making possible photographs and direct observations from the air by Navy patrols. Ash and steam were being erupted as a gray column from a vent at an altitude of about 3,600 feet in an amphitheater on the south west flank of Trident Volcano, and a blocky lava flow from this vent had spread over an area about 700 feet wide and 800 feet long (see fig. 2). Copious steam was being emitted from the area immediately adjacent on the uphill side of the active vent. The lava flow, apparently very slow moving and viscous, showed a surface of large blocks of lava formed as the stiffening material reached the lava surface. Earlier news dispatches had mentioned "long streams of molten lava" flowing down the mountain side but these must have been merely mudflows composed of meltwater and ash. A thin blanket of ash covered the area downwind (west) of the vent, lying on new snow which had concealed the ash deposits of previous days. No observations were made of the ash distribution around the neighboring volcanoes, so the uncertainty about the February 17 eruptions still remains.

Figure 2.—Sketch map of lava flow from Trident Volcano, February-June, 1953. (click on image for an enlargement in a new window)

On the next flight, February 21, the ash column was again gray and steam-laden, with copious steam also being emitted from the area on the uphill side, as on February 18, and the lava had advanced about half a mile southward down slope. If the rate of advance of the flow front can be taken as a reliable indication, it was during the period from February 18 to 21 that the lava rock was extruded most rapidly. On the flight of February 27 the eruptive column was light gray, and much steam came from the hot area on the uphill side of the vent. The lava front had extended several hundred feet further down slope. On March 4, low clouds obscured the vent, and a slight widening of the lava flow on the eastern side of the toe was all that could be seen. This eastern lobe, which was active until March 9 and which became reactivated in the late Spring, was a "squeeze-under, "that is, the lava forming the lobe was forced beneath the frozen eastern margin of the flow. From March 4 to March ??? 11 the flow, especially in the central portions, expanded like a balloon from internal additions. Then, from March 9 until the observation on March 11, further overflow from the vent had produced a northwest lobe. The ash puffs were progressively less frequent on each of the observations in early March, and the eruptive column on March 11 was very unsteady in the wind between bursts.

Except for reports of noticeably greater explosive activity on March 24, no further observations were made until April 6. Navy air photographs taken on April 6 indicate that the lava pile had bulged on the east and west flanks and increased in height in the vent area. Photographs on June 2 show further growth of the lava mound on the east flank and a landslide formed by slumping of a portion of the southeastern toe. Minor ash apparently had been deposited over the flow some time after April 6, and this surface had been partly overridden by new lava. By June 17 no further landsliding of consequence had occurred although a crevasse near the lip had widened appreciably. New lava was exuding slowly from the vent, which it buried completely, and was piling up at the source as well as spreading down the northwest, west, and northeast flanks. Steam with very little ash rose from the apex of the pile, from the northwest edge of the new lava, and, as had been normal since February 18, from the area at the northeast base of the pile. Concentric slump cracks were noticed in the latter area (see fig. 2).

In the evening of June 30, according to messages from the Navy at Kodiak, a fishing vessel reported ash in the air and pea-size pumice floating in Shelikof Strait from Cape Kuliuk, Kodiak Island, for a distance of 25 miles southwest. A patrol plane reported an ash column at Trident Volcano rising from a glowing vent and a fair amount of ash blanketing the area south of Katmai. Visibility was poor southeast of Trident as far as Kodiak Island, because of dust in the air. It is not certain whether the pumice in Shelikof Strait was newly erupted from Trident Volcano, however. It may have been derived from much older pumice deposits on Kodiak or the Alaskan Peninsula.