Eruptive History

Brief Geologic History of Karymsky

Karymsky Volcano occupies the majority of the 5 km diameter Karymsky caldera and is part of a larger volcanic center.  The caldera formed approximately 7.9 kyr after a catastrophic eruption. Lavas, pyroclastic density currents (PDCs), and fall out deposits built the modern cone of Karymsky throughout the last 5300 years (Izbekov et al., 2004).  Much of the cone is mantled with lava flows less than 200 years old (Global Volcanism Program). 

Karymsky volcano visible in the foreground (September 2000), forms a symmetrical cone 1536 m a.s.l.  The volcano is nested within an early Holocene caldera, the walls of which are visible on the lower left portion of the photograph.  To the south Karymsky Lake occupies mid-Pleistocene Academy Nauk caldera (Global Volcanism Program).   

Karymsky Lake, 60 m deep, is located 9 km to the south and occupies the Academy Nauk Caldera.  The caldera formed due to a large eruption 28-48 kyr ago and has remained relatively quiet ever since (Izbekov et al., 2004). 

Karymsky was extremely active throughout the 20^th century and continues in activity today.  Explosive and effusive activity was common during 1908-1915, 1921-1925, 1929-1935, 1943-1947, 1952-1967, 1970-1982, and 1996-present (Izbekov et al., 2004).    

Year(s)	VEI	Behavior
1908-1915	2	Central vent eruptions, explosive, lava flows
1921-1925	2	Central vent eruptions, explosive
1929-1935	2	Central vent eruptions, explosive, lava flows
1943-1947	2	Central vent eruptions, explosive, lava flows
1952-1967	3	Central vent eruptions, explosive, lava flows
1970-1982	3	Central vent eruptions, explosive, PDCs, lava flows, lava dome, lahars
1996-Present	3	Central vent eruptions, explosive, PDCs, lava flows, lava dome

1996- Current Eruption

The most recent and perhaps most interesting eruptive cycle of Karymsky started in January 1996 and continues at present.  In March 1995, after 13 years of dormancy, a significant increase in volcano-tectonic earthquakes occurred at both Karymsky and Academy Nauk caldera, 6 km to the south (Eichelberger and Izbekov, 2000).  After several months of unrest, the number of seismic events increased abruptly and culminated in a 6.6 magnitude earthquake on January 1, 1996, located 17 km south at 10 km depth.   The earthquake occurred along the same fault that connects Karymsky volcano and Academy Nauk caldera (Izbekov, 2004).  

On January 2, Karymsky began to erupt a steady gas-and-ash column from the summit, forming a 3 km high umbrella cloud, which drifted east from the volcano.   Shortly after, a separate eruption began and formed a new vent in the northern portion of Academy Nauk caldera beneath the lake surface (Izbekov, 2004).  The Karymsky vent and the newly formed Academy Nauk vent produced simultaneous eruptions for the following 18 hours.  Karymsky continued to emit a continuous ash plume, while Academy Nauk generated periodic phreato-magmatic eruptions.  The phreato-magmatic explosions lasted for 18 hours and sent juvenile and lithic bombs, ash, and water vapor 8 km a.s.l. (Izbekov, 2004). 

A powerful subaqueous explosion from the Academy Nauk vent on January 2, 1996.  Eruptions from this new vent lasted for 18 hours simultaneously with eruptions from Karymsky volcano (Izbekov et al., 2004) (Photo from Global Volcanism Program).     

Karymsky volcano (right) and Academy Nauk caldera (left) essentially erupted simultaneously during the initial 1996 eruption.  The phreatic nature of the Academy Nauk eruption caused high fragmentation of magmatic material and country rock.  The Academy Nauk vent ejected material over 8 km into the atmosphere (Izbekov et al., 2004) (Photo taken January 2, 1996 courtesy of the Global Volcanism Program). 

The intense phreatomagmatic eruptions at Academy Nauk built a cone and peninsula of proximal fall out deposits, which is partially submerged.  The eruption that built this feature only lasted for 18 hours on during January 1-2, 1996.      (Photo taken in July, 2008 courtesy of Pavel Izbekov - UAF).  

Karymsky volcano ejected bombs and ash continuously for the several days during the initial 1996 eruption.  Large, dense tephra fell out closer to the volcano, while less dense ash and gas remained suspended in the umbrella cloud as it drifted with prevailing winds (Photo taken January 2, 1996 courtesy of the Global Volcanism Program).

Despite the termination of the eruption at Academy Nauk, the eruption, Karymsky continued to erupt for the following 16 years until present day.  During the first 6 weeks after the initial eruption, eruptions remained frequent and unpredictable.  Large vulcanian eruptions produced large ash plumes and pyroclastic flows that extended down the flanks of the cone (Izbekov, 2004).   Since the onset of the eruption, the volcano has undergone periods of strombolian-vulcanian style eruptions with regular intervals between eruptions and very irregular explosive vulcanian eruptions (Izbekov, 2004).

Geodetic measurements completed in the summer following the initial eruption showed that the fault, along which Karymsky and Academy Nauk are located, showed significant extension.  The extension is thought to be the result of a dike that slowly intruded the pre-existing fault directly beneath the two vents (Eichelberger and Izbekov, 2000).  The intersection of the rising dike and the magma chamber beneath Karymsky triggered the eruption in 1996 (Izbekov et al., 2004). 

The Academia Nauk Caldera is in the foreground and Karymsky volcano is seen in the background.  The phreato-magmatic eruptions in Academy Nauk created a new peninsula, with a deep explosion crater in the northern end of the lake.  The dike intrusion caused extension along the N-S fracture zone (Figure from Walter 2007 p. 351), however there was no vertical displacement along the fault as is indicated in the figure above (Pavel Izbekov, personal communication).  

Current Activity

Karymsky volcano remains very active today.  Based on seismic data and visual observations, approximately 45 strombolian-vulcanian eruptions occurred in 2012 (Global Volcanism Program).  Of all the reported and observed eruptions, Karymsky ash plumes rose to an average height of 3.4 km a.s.l.  A maximum observed ash plume height of 6.7 km a.s.l. was observed on October 6, 2012. 

Typical Vulcanian style eruption of Karymsky volcano with a large ash plume.  Many occurred like this from January-April, 2006.   A small PDC can seen on the upper left flank flowing down to the left.  Vulcanian-style eruptions are sporadic and explosive by nature  (Photo from Global Volcanism Program). 

Typical Vulcanian style eruption with a large ash plume and PDC, which can be seen cascading down the flanks of Karymsky volcano in October 2009 (Photo from Global Volcanism Program).

This volcanic bomb was thrown from Karymsky volcano during a typical Vulcanian eruption.  The outside of the juvenile bomb cooled quickly, while the interior remained molten.  The outside crust cracked as heat tried to escape during transport and after landing (Photo taken in July 2008, courtesy of Pavel Izbekov - UAF).  

This bomb was recently thrown from Karymsky volcano during a Vulcanian eruption.  The crust cooled as it flew through the air and continued to cool upon landing, while the interior remained insulated and molten (Photo taken in August 1999, courtesy of Pavel Izbekov - UAF).