Nevado del Ruiz (Colombia)
Six weeks of harmonic tremor; increased SO2; light ashfalls
Tacaná (Mexico)
Gas emission continues but seismicity declines
Concepcion (Nicaragua)
Gas and ash emission; flank vegetation killed
Momotombo (Nicaragua)
Fumarole temperatures decline after heavy rains
Pelée (Martinique, West Indies)
Seismicity in 1929 crater
Kilauea (Hawaii, USA)
Episodes 45 and 46 of East Rift eruption
St. Helens (Washington, USA)
Activity returns to background levels
Augustine (Alaska, USA)
Activity subsides after dome extrusion
Pavlof (Alaska, USA)
Strombolian activity feeds lava flow; seismicity increases
Shishaldin (Aleutian Islands, USA)
Steam plumes with some ash
Akutan (Aleutian Islands, USA)
Steam and ash emission
Atka (Aleutian Islands, USA)
Steam emission follows magnitude 7.7 earthquake
Macdonald (south-central Pacific Ocean)
First seismic crisis in 4 years
Rabaul (New Britain Island, Papua New Guinea)
Seismicity remains elevated; slight inflation
Langila (New Britain Island, Papua New Guinea)
Explosions and glow
Ulawun (New Britain Island, Papua New Guinea)
Tremor & low-frequency seismicity but no eruptions seen
Manam (Bismarck Sea, Papua New Guinea)
Steam and ash emission
Bagana (Bougainville Island)
Plumes; rockfall events from active lava flow
Iliboleng (Lesser Sunda Islands, Indonesia)
Explosion; grassfires from ashfall; 570 evacuated
Sangeang Api (Lesser Sunda Islands, Indonesia)
Explosions and lava flow advance continue
Semeru (Java, Indonesia)
Explosions continue, nuée adente observed
Tangkubabparahu (Java, Indonesia)
Fumarole temperarures remain high
Lokon-Empung (Sulawesi, Indonesia)
Small explosion is only activity since April
Kanlaon (Central Philippines)
Minor ash ejection
Sakura-jima (Kyushu, Japan)
Fewer explosions
Etna (Sicily, Italy)
Strombolian activity and gas emission
Atmospheric Effects
Ruiz aerosols persist; balloon data since 1971
Nevado del Ruiz (Colombia)
Strong seismicity continues; deformation NW of the summit
Tacaná (México)
Seismicity declines after May explosion; steaming
Kilauea (Hawaii, USA)
Intermittent activity precedes episode 47
St. Helens (Washington, USA)
Activity at background levels
Pavlof (Alaska, USA)
Strombolian activity feeds lava flow; strong seismicity
Cleveland (Aleutian Islands, USA)
Incandescent tephra
Makushin (Aleutian Islands, USA)
Increased steam plume
Sakura-jima (Kyushu, Japan)
Airliner lands safely after flying through ash cloud
Kusatsu-Shirane (Honshu, Japan)
Increase in microearthquakes since 1984
Fukutoku-Okanoba (Volcano Islands, Japan)
Discolored sea water
Pumice Rafts (Ryukyu Islands, Japan)
Discolored seawater
Kanlaon (Central Philippines)
Renewed explosions and seismicity
Rabaul (New Britain Island, Papua New Guinea)
Seismicity remains high until late June
Langila (New Britain Island, Papua New Guinea)
Occasional explosions; light ashfalls
Manam (Bismarck Sea, Papua New Guinea)
More vigorous exlosions; inflation
Sorikmarapi (Sumatra, Indonesia)
Dark ash plume
Talang (Sumatra, Indonesia)
Thermal field grows; steaming increases
Semeru (Java, Indonesia)
Continued small explosions
Tangkubanparahu (Java, Indonesia)
Fumarole temperatures still high
Lokon-Empung (Sulawesi, Indonesia)
Small explosion
Sangeang Api (Lesser Sunda Islands, Indonesia)
Explosions and crater glow continue
Stromboli (Italy)
Strombolian activity; small lava flows
Piton de la Fournaise (Reunion Island)
Brief eruption from March pit crater
Atmospheric Effects
Ruiz aerosols persist; 1985-86 lidar data summarized
Nevado del Ruiz (Colombia)
Ash emissions preceded by B-type swarms and shallow events
Arenal (Costa Rica)
Increased seismicity with gas/ash emissions & lava flows
Augustine (Alaska, USA)
Slow lava dome growth; pyroclastic flows; vigorous fuming
Pavlof (Alaska, USA)
Continued Strombolian activity and vigorous seismicity
St. Helens (Washington, USA)
Activity remains at background levels
Long Valley (California, USA)
Nearby earthquakes cause no pronounced seismicity and deformation change in caldera
Kilauea (Hawaii, USA)
Episode 48 from three new fissures
Bezymianny (Kamchatka Peninsula, Russia)
Lava extrusion; pyroclastic flows
Sakura-jima (Kyushu, Japan)
Explosions; heavy ashfall
Suwanose-jima (Ryukyu Islands, Japan)
Explosions cause 200 m plume
Sorikmarapi (Sumatra, Indonesia)
No new explosions
Talang (Sumatra, Indonesia)
Dark fume accompanies increased thermal activity
Lokon-Empung (Sulawesi, Indonesia)
Small explosions eject daily ash clouds
Sangeang Api (Lesser Sunda Islands, Indonesia)
Ash clouds; red glow above crater
Iliboleng (Lesser Sunda Islands, Indonesia)
800-m eruption cloud
Rabaul (New Britain Island, Papua New Guinea)
Seismicity declines moderately, ground deformation low
Langila (New Britain Island, Papua New Guinea)
Weak seismicity and vapor emission
Manam (Bismarck Sea, Papua New Guinea)
Increased ash production, rumbling
Bagana (Bougainville Island)
Ash emission declines, lava flow still active
Rumble III (Kermadec Ridge, New Zealand)
Submarine activity discolors water; hydrophone noise
Kavachi (Solomon Islands)
Submarine activity
Piton de la Fournaise (Reunion Island)
Small pit crater eruption follows seismicity
Nyamuragira (DR Congo)
Reported S-flank eruption
Atmospheric Effects
Ruiz stratospheric aerosols persist
Oku Volcanic Field (Cameroon)
Toxic gas cloud from Lake Nyos kills more than 1,700 people
Nyamuragira (DR Congo)
SSW flank fissure eruption feeds 17 km lava flow
Augustine (Alaska, USA)
Dome growth; pyroclastic flows observed from close range
Pavlof (Alaska, USA)
Strombolian activity and ash emission ends
Shishaldin (Aleutian Islands, USA)
Large steam plumes with some ash
Akutan (Aleutian Islands, USA)
Ash plumes from caldera cinder cones
St. Helens (Washington, USA)
Earthquake swarm and small plume emission
Kilauea (Hawaii, USA)
Lava shield continues to grow
Nevado del Ruiz (Colombia)
Stronger deformation; seismicity builds after brief decline
Lascar (northern Chile)
Hypersthene andesite ashfall 350 km to the SE
Oshima (Izu Islands, Japan)
Tremor and earthquake swarm but no change in thermal activity
Sakura-jima (Kyushu, Japan)
More explosions; earthquake swarms
Rabaul (New Britain Island, Papua New Guinea)
Seismicity declines; deformation at pre-crisis level
Langila (New Britain Island, Papua New Guinea)
Weak vapor emission
Manam (Bismarck Sea, Papua New Guinea)
South Crater ash emission; small low-frequency earthquakes
Bagana (Bougainville Island)
Continued viscous lava extrusion; small explosions
White Island (New Zealand)
Continued minor phreatomagmatic activity
Ruapehu (North Island, New Zealand)
Crater Lake temperature rises after 5-month decline
Atmospheric Effects
Ruiz aerosol layer broader and less intense
Oku Volcanic Field (Cameroon)
Additional observations by Italian team
Stromboli (Italy)
Intermittent lava fountains from summit lava lake after lava flow production ends; tourist killed near summit vent
Etna (Sicily, Italy)
Strombolian activity and lava flow, then strong explosion
Nevado del Ruiz (Colombia)
Seismicity, deformation, and SO2 emission decline
El Chichón (México)
Magnitude 3 earthquake nearby but crater unchanged
Tacaná (México)
New fumaroles above 8 May crater
St. Helens (Washington, USA)
New lobe extruded onto composite lava dome
Kilauea (Hawaii, USA)
Lava tubes feed flow complex; continued lava shield growth
Loihi (Hawaii, USA)
Earthquake swarm
Akutan (Aleutian Islands, USA)
More June ash observations
Shishaldin (Aleutian Islands, USA)
Steam and ash emission
Rabaul (New Britan)
Seismicity and deformation remain at low levels
Bagana (Bougainville Island)
Small summit exlosion; rockfall events decline
Manam (Bismarck Sea, Papua New Guinea)
Dense ash clouds; light ashfall; roaring
Tangkubanparahu (Java, Indonesia)
Fumarole temperatures increase
Semeru (Java, Indonesia)
Frequent summit Vulcanian explosions continue
Sangeang Api (Lesser Sunda Islands, Indonesia)
Fewer explosions
Lokon-Empung (Sulawesi, Indonesia)
Explosions eject breadcrust bombs
Sakura-jima (Kyushu, Japan)
Explosions and earthquake swarms
Oshima (Izu Islands, Japan)
More earthquakes; continued tremor; rumbling
Atmospheric Effects
New aerosol layers seen over Alaska
Pavlof (Alaska, USA)
Ash emission and lava fountaining
St. Helens (Washington, USA)
Strong seismicity and tilt with October extrusion
Kilauea (Hawaii, USA)
Continued lava production builds shield; flows burn forest
Morne Plat Pays (Dominica, West Indies)
Earthquake swarms but thermal activity unchanged
Nevado del Ruiz (Colombia)
Strong earthquake swarm but weaker tremor
Etna (Sicily, Italy)
Lava flows and Strombolian activity from SE fissures and crater
Oshima (Izu Islands, Japan)
Eruption column to 3,200 m after four months of seismicity
Submarine Explosion (Kermadec Islands, SW Pacific Ocean)
Violent underwater explosion reported
Rabaul (New Britain Island, Papua New Guinea)
Seismicity and deformation remain at low levels
Bagana (Bougainville Island)
Continued lava extrusion; vapor emissions
Manam (Bismarck Sea, Papua New Guinea)
Seismicity increases slightly; weak vapor emissions
Ulawun (New Britain Island, Papua New Guinea)
Low-level seismicity; weak vapor emissions
Langila (New Britain Island, Papua New Guinea)
Low-level seismicity; weak vapor emissions
Merapi (Java, Indonesia)
Rockfall seismicity suggests increased lava dome growth
Lokon-Empung (Sulawesi, Indonesia)
Periodic explosions; no additional juvenile tephra
Semeru (Java, Indonesia)
Vulcanian explosions continue
Sangeang Api (Lesser Sunda Islands, Indonesia)
Explosions continue
Ruapehu (North Island, New Zealand)
Crater Lake temperature increases from July low
Atmospheric Effects
New stratospheric aerosols over Europe, Japan, and USA; 24 September Etna eruption possible source
Bezymianny (Kamchatka Peninsula, Russia)
Lava extrusions; explosions feed pyroclastic flows
Chikurachki (Kurile Islands, Russia)
5-km-high ash column; lava and pyroclastic flows
Oshima (Izu Islands, Japan)
Lava from summit vent and two fissures; epicenters plot along NW/SE axis; 12,000 evacuated; summit deflated before eruption
Sakura-jima (Kyushu, Japan)
Ash and block eruptions; 2.5 m block injures six people
Suwanose-jima (Ryukyu Islands, Japan)
500-600-m-high ash plume
Kilauea (Hawaii, USA)
12-km-long lava flow destroys 11 houses, enters ocean
Merapi (Java, Indonesia)
Summit lava dome growth
Lokon-Empung (Sulawesi, Indonesia)
Frequent explosions; ashfall to the SE
Sangeang Api (Lesser Sunda Islands, Indonesia)
Numerous explosions
Iliboleng (Lesser Sunda Islands, Indonesia)
Renewed explosions after 12 days of seismicity
Rabaul (New Britain Island, Papua New Guinea)
Swarms with strongest earthquake since May 1985
Ulawun (New Britain Island, Papua New Guinea)
Low levels of seismicity and steam emission
Langila (New Britain Island, Papua New Guinea)
Ash emission; low levels of seismicity
Manam (Bismarck Sea, Papua New Guinea)
Both summit craters emit ash
Bagana (Bougainville Island)
Lava extrusion continues
White Island (New Zealand)
Ash emission and continuing seismicity
Submarine Explosion (Kermadec Islands, SW Pacific Ocean)
Probably an earthquake in the Tonga Trench
Piton de la Fournaise (Reunion Island)
Ash eruption; lava from fissure
Etna (Sicily, Italy)
Fissure eruption continues
Nevado del Ruiz (Colombia)
High seismicity; temperatures increase in hot springs
Masaya (Nicaragua)
Rock landslides and wall collapse in Santiago Crater
Santa Maria (western Guatemala)
Lateral blast and pyroclastic flow on S flank
Pacaya (Guatemala)
Two small new cones in MacKenny Crater; flank lava flows
Michoacán-Guanajuato (Mexico)
Temperature of hottest fumarole declines; HCl-rich gases
Colima (western México)
Small plume with minor SO2
St. Helens (Washington, USA)
Seismicity and SO2 emissions at background
Pavlof (Alaska, USA)
Eruption continues; lava flow reaches ocean
Atmospheric Effects
Enhanced aerosols persist; perhaps brought from tropics by seasonal winds
Oku Volcanic Field (Cameroon)
Three explosions in 5 minutes; red stain in lake center the next morning
Etna (Sicily, Italy)
Lava flows; Strombolian activity; ash emission
Piton de la Fournaise (Reunion Island)
Lava from fissure fills pit crater
Erebus (Antarctica)
Frequent explosions from lava lake
Kliuchevskoi (Kamchatka Peninsula, Russia)
Lava flow and incandescent tephra
Chikurachki (Kurile Islands, Russia)
Nimbus-7 satellite detects SO2 plume
Okmok (Aleutian Islands, USA)
Tephra eruption and debris flow
Pavlof (Alaska, USA)
Strong tremor accompanied early December lava flows; steaming from summit and flank fissures
Shishaldin (Aleutian Islands, USA)
Vigorous steam ejection
St. Helens (Washington, USA)
Activity at background level
Kilauea (Hawaii, USA)
Lava destroys more homes
Nevado del Ruiz (Colombia)
Shallow seismicity; minor ash emission; less SO2
Pacaya (Guatemala)
Ejected blocks cause at least 12 injuries, damage roofs
Pumice Raft (South China Sea)
Pumice from unknown source clogs ship's intakes
Rabaul (New Britain Island, Papua New Guinea)
Seismicity at lowest level since January 1986
Langila (New Britain Island, Papua New Guinea)
Light ashfall; weak seismicity
Manam (Bismarck Sea, Papua New Guinea)
Ash emissions and rumbling; seismicity continues
Bagana (Bougainville Island)
Lava extrusion probably continuing
Merapi (Java, Indonesia)
Lava flow from October-November dome advances onto SW flank
Semeru (Java, Indonesia)
Frequent summit explosions continue
Lokon-Empung (Sulawesi, Indonesia)
Continued small explosions and seismicity
Sangeang Api (Lesser Sunda Islands, Indonesia)
Small explosions but no seismicity
Ruapehu (North Island, New Zealand)
Crater lake cools
Atmospheric Effects
Continued fluctuations in stratospheric aerosols
1986
