Event Name : Veniaminof 1993/7
|Start:||July 30, 1993 ||Observed|
|Stop:||August 28, 1994 ||Observed|
|Lava flow: ||
|Tephra plume: ||
|Central eruption: ||
|"Fire", "Glowing", or incandescence: ||
|Duration: ||Approximately 1 year ||
|MaxVEI: ||2 ||
|ColHeight: ||5500 m ||
From Neal and others (1996): "Reports of activity at Veniaminof began in early 1993. Pilots reported a steam plume rising from the volcano on February 18, 1993. Confirmed magmatic activity was first sighted on July 30, 1993. Observers in Perryville reported black clouds rising over the summit beginning at 1430 ADT on July 30, 1993. A white steam cloud was present at other times. A small eruption plume was observed on satellite imagery by the NWS on July 30, but none were seen in the following days. On the morning of July 31, Perryville observers saw a gray cloud rising from the volcano and extending to the south. On August 2, commercial airline pilots observed intermittent venting of black ash clouds rising nearly 300 m (1,000 ft) above the active intracaldera cone. On August 3, U.S. Fish and Wildlife (USFWS) personnel reported a steaming pit in the snow at base of the west side of the intracaldera cinder cone. Pilot reports on August 3 described black ash and bombs erupting from the summit vent of the intracaldera cone at 30-60 second intervals to a height of 2,400 - 3,000 m (7,900-9,800 ft) above sea level (840 m [2,756 ft] above vent). A minor dusting of very fine ash occurred in Port Heiden after 2000 ADT on August 3, 1993. Residents of Perryville, Chignik, and Chignik Lake also heard a "rumbling noise" accompanied by a slight tremor at about 2200 that night. Flight restrictions around Veniaminof were put into effect August 4, 1993. On the morning of August 6, a resident of Port Heiden observed eruptions of ash and steam at 3-4 minute intervals; these plumes barely rose above the summit of the volcano. There were no reports of ashfall at other nearby villages. On August 12, a pilot reported ash venting 600-900 m (1,900 - 3,000 ft) above the crater with the ash cloud carried east-northeast.
"Poor weather precluded many observations during the fall. On October 1-2, residents of Port Heiden observed steam and ash emissions over Veniaminof. An Advanced Very High Resolution Radiometer (AVHRR) image from the late morning of October 2 -- the first clear satellite image in almost two months -- showed a faint northeast-directed plume and a thermal anomaly at the summit cinder cone. During the night of October 7, residents of Perryville observed bursts of incandescent material rising approximately 300 m (1,000 ft) above the summit. These bursts occurred about once every 10 minutes, were accompanied by loud rumbling sounds, and appeared to be similar in size to the eruptions in July and August. On October 14, residents of Perryville observed continued emission of a gray, steam and ash plume rising about 1 km (3,280 ft) above the summit. Though the summit was obscured by haze on October 22, observations from Perryville indicated a decrease in the level of activity relative to that earlier in the month.
"U.S. Coast Guard (USCG) pilots filmed eruptive activity and took photos of the intracaldera cinder cone on November 6, 1993. By then, a new pit (2.0 by 0.75 km [1.2 by 0.5 mi] wide) had formed in the ice adjacent to the cone on the east flank and contained an
active lava flow [See fig. 4 in original text]. Steam plumes rose from the outer margin of the lava where it came into contact with the ice walls of the pit. An ash-and-steam plume rose up to 2 km (6,560 ft) above the cinder cone, and a thin ash layer covered the ice-filled floor of the caldera.
"Activity continued intermittently for the remainder of 1993, (for post-1993 activity see Neal and others, 1995). During favorable wind and weather conditions, Port Heiden residents noted dark ash clouds above the volcano and deep rumbling was reported by residents in Port Heiden and Perryville."
From Neal and others (1995): "Reports of eruptive activity diminished in frequency with the onset of bad winter weather; however, reports of renewed, intermittent strombolian activity reached AVO in March 1994. On May 9, 1994, during the first AVO overflight, eruptive activity consisted of quiet lava effusion from the vicinity of the intracaldera cinder cone [see fig. 7 in original text]. This lava flow had melted an oval-shaped pit in the summit ice cap estimated to be about 1000 m (3,280 ft) by 800 m (2,625 ft) across and 30-50 m (100-160 ft) deep. Fractures in the ice surrounding the pit suggested subglacial melting. Unlike the 1983-84 eruption, no standing water was visible in the pit.
"On June 29, an especially vigorous eruption sent an ash cloud to a reported 4.8 - 5.5 km (16,000-18,000 ft) and the NWS issued a SIGMET (notice of SIGnificant METeorological events.) Additional reports of low ash bursts over the volcano or incandescent strombolian activity viewed at night were received through mid-August. Steam plumes, at times rising several hundred meters, were reported over the volcano until late September. Due to the remote nature of this volcano, the paucity of observations, and the frequently poor weather, we are uncertain of the history of declining eruptive activity in late 1994. However, on Advanced Very High Resolution Radiometer (AVHRR) satellite images unobscured by heavy cloud cover, thermal anomalies were detected in the area of the active intracaldera cinder cone of Mount Veniaminof into early 1995."
The Smithsonian Institution (Bulletin of Global Volcanism, volume 19, number 4) estimates the volume of the 1993-1994 lava field at 16-20 x 10^6 cubic meters.