Active volcanoes in the world: August 3 - 9, 2016

Active volcanoes in the world: August 3 - 9, 2016

New activity/unrest was observed at 5 volcanoes between August 3 and 9, 2016. During the same period, ongoing activity was observed at 14 volcanoes.

New activity/unrest: Brava, Cape Verde  | Chikurachki, Paramushir Island (Russia)  | Chirpoi, Kuril Islands (Russia)  | Gamalama, Halmahera (Indonesia)  | Kilauea, Hawaiian Islands (USA).

Ongoing activity: Aira, Kyushu (Japan)  | Alaid, Kuril Islands (Russia)  | Bagana, Bougainville (Papua New Guinea)  | Dukono, Halmahera (Indonesia)  | Etna, Sicily (Italy)  | Klyuchevskoy, Central Kamchatka (Russia)  | Nevado del Ruiz, Colombia  | Nevados de Chillán, Chile  | Pavlof, United States  | Reventador, Ecuador  | Santa Maria, Guatemala  | Sheveluch, Central Kamchatka (Russia)  | Sinabung, Indonesia  | Yasur, Vanuatu.

New activity/unrest

Brava, Cape Verde
14.85°N, 24.72°W, Summit elev. 900 m

According to the Universidade de Cabo Verde in a report posted on 4 August, Instituto Nacional da Meteorologia e Geofísica (INMG) recorded increased seismicity at Brava beginning at dawn on 2 August. In response authorities evacuated 300 people, based on a news report. Earthquakes were felt by residents during 3-4 August. Scientists and technicians from the Universidade de Cabo Verde (UniCV), Instituto Vulcanológico das Canárias (INVOLCAN), and Serviço Nacional da Protecção Civil (SNPC) began monitoring carbon dioxide emissions though found nothing unusual during 4-7 August.

Geological summary: Brava Island, 20 km west of Fogo, is the westernmost of the southern Cape Verde islands. The 10-km-wide island contains 15 morphologically youthful craters located along two or three lineaments intersecting along the crest of the island. The youthfulness of the craters and numerous minor earthquakes in recent years indicate that a significant volcanic hazard still exists (Wolff and Turbeville, 1985). Most of the younger eruptions originated from the interaction of phonolitic magmas with a large groundwater reservoir contained within an older volcanic series characterized by thick welded ignimbrites and block-and-ash flow deposits. Carbonatitic lavas are also found on Brava.

Chikurachki, Paramushir Island (Russia)
50.324°N, 155.461°E, Summit elev. 1781 m

KVERT reported that a moderate explosive eruption at Chikurachki was observed during 27-28 July. Ash plumes rose to altitudes of 4-5 km (13,100-16,400 ft) a.s.l. and drifted NE. Minor ashfall was reported in Severo-Kurilsk (Paramushir Island) on 27 July. After the heightened activity conditions remained quiet through 4 August. The Aviation Color Code remained at Orange (the second highest level on a four-color scale).

Geological summary: Chikurachki, the highest volcano on Paramushir Island in the northern Kuriles, is actually a relatively small cone constructed on a high Pleistocene volcanic edifice. Oxidized basaltic-to-andesitic scoria deposits covering the upper part of the young cone give it a distinctive red color. Frequent basaltic plinian eruptions have occurred during the Holocene. Lava flows from 1781-m-high Chikurachki reached the sea and form capes on the NW coast; several young lava flows also emerge from beneath the scoria blanket on the eastern flank. The Tatarinov group of six volcanic centers is located immediately to the south of Chikurachki, and the Lomonosov cinder cone group, the source of an early Holocene lava flow that reached the saddle between it and Fuss Peak to the west, lies at the southern end of the N-S-trending Chikurachki-Tatarinov complex. In contrast to the frequently active Chikurachki, the Tatarinov volcanoes are extensively modified by erosion and have a more complex structure. Tephrochronology gives evidence of only one eruption in historical time from Tatarinov, although its southern cone contains a sulfur-encrusted crater with fumaroles that were active along the margin of a crater lake until 1959.

Chirpoi, Kuril Islands (Russia)
46.525°N, 150.875°E, Summit elev. 742 m

SVERT reported that a thermal anomaly over Snow, a volcano of Chirpoi, was detected in satellite images during 6-7 August. The Aviation Color Code remained at Yellow.

Geological summary: Chirpoi, a small island lying between the larger islands of Simushir and Urup, contains a half dozen volcanic edifices constructed within an 8-9 km wide, partially submerged caldera. The southern rim of the caldera is exposed on nearby Brat Chirpoev Island. The symmetrical Cherny volcano, which forms the 691 m high point of the island, erupted twice during the 18th and 19th centuries. The youngest volcano, Snow, originated between 1770 and 1810. It is composed almost entirely of lava flows, many of which have reached the sea on the southern coast. No historical eruptions are known from 742-m-high Brat Chirpoev, but its youthful morphology suggests recent strombolian activity.

Gamalama, Halmahera (Indonesia)
0.8°N, 127.33°E, Summit elev. 1715 m

Based on analyses of satellite imagery and model data, and information from PVMBG, the Darwin VAAC reported that during 3-4 August ash plumes from Gamalama rose to an altitude of 2.7 km (9,000 ft) a.s.l. and drifted S, SE, E, and NE. On 5 August PVMBG noted that seismicity continued to be elevated although inclement weather prevented visual observations.

Geological summary: Gamalama is a near-conical stratovolcano that comprises the entire island of Ternate off the western coast of Halmahera, and is one of Indonesia's most active volcanoes. The island was a major regional center in the Portuguese and Dutch spice trade for several centuries, which contributed to the thorough documentation of Gamalama's historical activity. Three cones, progressively younger to the north, form the summit. Several maars and vents define a rift zone, parallel to the Halmahera island arc, that cuts the volcano. Eruptions, recorded frequently since the 16th century, typically originated from the summit craters, although flank eruptions have occurred in 1763, 1770, 1775, and 1962-63.

Kilauea, Hawaiian Islands (USA)
19.421°N, 155.287°W, Summit elev. 1222 m

During 3-9 August HVO reported that the lava lake continued to rise and fall, circulate, and spatter in Kilauea’s Overlook vent. Late on 6 August an explosions triggered by a rockfall into the lake ejected voluminous amounts of hot spatter and rock debris onto the SE rim of Halema’uma’u Crater, covering a broad swath 80 m long and 50 m wide around the formerly-closed public overlook area.

Several incandescent vents on Pu’u ‘O’o Crater’s floor were evident in webcam images. The 61G lava flow, originating from a vent on Pu’u ‘O’o Crater’s E flank, continued to enter the ocean at Kamokuna in an area that spans 150-240 m wide. A small delta had formed at the entry. An active lobe of lava advanced along the W side of the flow field, crossed the Emergency Access road 500 m W of the main flow, and entered the ocean overnight during 8-9 August.

Geological summary: Kilauea volcano, which overlaps the east flank of the massive Mauna Loa shield volcano, has been Hawaii's most active volcano during historical time. Eruptions are prominent in Polynesian legends; written documentation extending back to only 1820 records frequent summit and flank lava flow eruptions that were interspersed with periods of long-term lava lake activity that lasted until 1924 at Halemaumau crater, within the summit caldera. The 3 x 5 km caldera was formed in several stages about 1500 years ago and during the 18th century; eruptions have also originated from the lengthy East and SW rift zones, which extend to the sea on both sides of the volcano. About 90% of the surface of the basaltic shield volcano is formed of lava flows less than about 1100 years old; 70% of the volcano's surface is younger than 600 years. A long-term eruption from the East rift zone that began in 1983 has produced lava flows covering more than 100 sq km, destroying nearly 200 houses and adding new coastline to the island.

Ongoing activity

Aira, Kyushu (Japan)
31.593°N, 130.657°E, Summit elev. 1117 m

JMA reported that on 4 August a small-scale explosion occurred at Minamidake summit crater (at Aira Caldera’s Sakurajima volcano) ejecting material as high as 400 m above the crater rim. The Alert Level remained at 3 (on a 5-level scale).

Geological summary: The Aira caldera in the northern half of Kagoshima Bay contains the post-caldera Sakurajima volcano, one of Japan's most active. Eruption of the voluminous Ito pyroclastic flow accompanied formation of the 17 x 23 km caldera about 22,000 years ago. The smaller Wakamiko caldera was formed during the early Holocene in the NE corner of the Aira caldera, along with several post-caldera cones. The construction of Sakurajima began about 13,000 years ago on the southern rim of Aira caldera and built an island that was finally joined to the Osumi Peninsula during the major explosive and effusive eruption of 1914. Activity at the Kitadake summit cone ended about 4850 years ago, after which eruptions took place at Minamidake. Frequent historical eruptions, recorded since the 8th century, have deposited ash on Kagoshima, one of Kyushu's largest cities, located across Kagoshima Bay only 8 km from the summit. The largest historical eruption took place during 1471-76.

Alaid, Kuril Islands (Russia)
50.861°N, 155.565°E, Summit elev. 2285 m

KVERT reported that moderate activity at Alaid’s summit crater was detected during 29 July-5 August. Satellite images showed a thermal anomaly at the volcano during 2-3 August. The Aviation Color Code remained at Orange (the second highest level on a four-color scale).

Geological summary: The highest and northernmost volcano of the Kuril Islands, 2285-m-high Alaid is a symmetrical stratovolcano when viewed from the north, but has a 1.5-km-wide summit crater that is breached widely to the south. Alaid is the northernmost of a chain of volcanoes constructed west of the main Kuril archipelago and rises 3000 m from the floor of the Sea of Okhotsk. Numerous pyroclastic cones dot the lower flanks of basaltic to basaltic-andesite Alaid volcano, particularly on the NW and SE sides, including an offshore cone formed during the 1933-34 eruption. Strong explosive eruptions have occurred from the summit crater beginning in the 18th century. Reports of eruptions in 1770, 1789, 1821, 1829, 1843, 1848, and 1858 were considered incorrect by Gorshkov (1970). Explosive eruptions in 1790 and 1981 were among the largest in the Kuril Islands during historical time.

Bagana, Bougainville (Papua New Guinea)
6.137°S, 155.196°E, Summit elev. 1855 m

Based on analyses of satellite imagery and model data, the Darwin VAAC reported that during 3-8 August ash plumes from Bagana rose to an altitude of 2.1 km (7,000 ft) a.s.l. and drifted SW, WSW, W, and NW.

Geological summary: Bagana volcano, occupying a remote portion of central Bougainville Island, is one of Melanesia's youngest and most active volcanoes. This massive symmetrical, roughly 1850-m-high cone was largely constructed by an accumulation of viscous andesitic lava flows. The entire edifice could have been constructed in about 300 years at its present rate of lava production. Eruptive activity is frequent and characterized by non-explosive effusion of viscous lava that maintains a small lava dome in the summit crater, although explosive activity occasionally producing pyroclastic flows also occurs. Lava flows form dramatic, freshly preserved tongue-shaped lobes up to 50-m-thick with prominent levees that descend the volcano's flanks on all sides. Satellite thermal measurements indicate a continuous eruption from before February 2000 through at least late August 2014.

Dukono, Halmahera (Indonesia)
1.693°N, 127.894°E, Summit elev. 1229 m

Based on ground reports from PVMBG, satellite data, and model data, the Darwin VAAC reported that during 3 and 6-9 August ash plumes from Dukono rose to altitudes of 1.8-3.3 km (6,000-11,000 ft) a.s.l. and drifted NW, N, E, and SE.

Geological summary: Reports from this remote volcano in northernmost Halmahera are rare, but Dukono has been one of Indonesia's most active volcanoes. More-or-less continuous explosive eruptions, sometimes accompanied by lava flows, occurred from 1933 until at least the mid-1990s, when routine observations were curtailed. During a major eruption in 1550, a lava flow filled in the strait between Halmahera and the north-flank cone of Gunung Mamuya. This complex volcano presents a broad, low profile with multiple summit peaks and overlapping craters. Malupang Wariang, 1 km SW of the summit crater complex, contains a 700 x 570 m crater that has also been active during historical time.

Etna, Sicily (Italy)
37.734°N, 15.004°E, Summit elev. 3330 m

INGV reported that during mid-July weak ash emissions rose from a vent located high on the E flank of Etna’s New Southeast Crater (NSEC) cone. The emissions continued periodically until early August. Pulsating glow from mild, intra-crater explosions in the Voragine (VOR) crater was recorded during 7-9 August.

Geological summary: Mount Etna, towering above Catania, Sicily's second largest city, has one of the world's longest documented records of historical volcanism, dating back to 1500 BCE. Historical lava flows of basaltic composition cover much of the surface of this massive volcano, whose edifice is the highest and most voluminous in Italy. The Mongibello stratovolcano, truncated by several small calderas, was constructed during the late Pleistocene and Holocene over an older shield volcano. The most prominent morphological feature of Etna is the Valle del Bove, a 5 x 10 km horseshoe-shaped caldera open to the east. Two styles of eruptive activity typically occur at Etna. Persistent explosive eruptions, sometimes with minor lava emissions, take place from one or more of the three prominent summit craters, the Central Crater, NE Crater, and SE Crater (the latter formed in 1978). Flank vents, typically with higher effusion rates, are less frequently active and originate from fissures that open progressively downward from near the summit (usually accompanied by strombolian eruptions at the upper end). Cinder cones are commonly constructed over the vents of lower-flank lava flows. Lava flows extend to the foot of the volcano on all sides and have reached the sea over a broad area on the SE flank.

Klyuchevskoy, Central Kamchatka (Russia)
56.056°N, 160.642°E, Summit elev. 4754 m

KVERT reported that a Strombolian eruption at Klyuchevskoy continued during 29 July-5 August. Volcanic bombs that were ejected 200-300 m above the summit crater and 50 m above a cinder cone landed in the Apakhonchich drainage on the SE flank. A lava flow traveled down the Apakhonchich drainage. Satellite images showed a large and intense daily thermal anomaly at the volcano, and ash plumes drifting about 200 km NE, E, and NW during 31 July, 1 August, and 3-4 August. The Aviation Color Code remained at Orange.

Geological summary: Klyuchevskoy (also spelled Kliuchevskoi) is Kamchatka's highest and most active volcano. Since its origin about 6000 years ago, the beautifully symmetrical, 4835-m-high basaltic stratovolcano has produced frequent moderate-volume explosive and effusive eruptions without major periods of inactivity. It rises above a saddle NE of sharp-peaked Kamen volcano and lies SE of the broad Ushkovsky massif. More than 100 flank eruptions have occurred during the past roughly 3000 years, with most lateral craters and cones occurring along radial fissures between the unconfined NE-to-SE flanks of the conical volcano between 500 m and 3600 m elevation. The morphology of the 700-m-wide summit crater has been frequently modified by historical eruptions, which have been recorded since the late-17th century. Historical eruptions have originated primarily from the summit crater, but have also included numerous major explosive and effusive eruptions from flank craters.

Nevado del Ruiz, Colombia
4.892°N, 75.324°W, Summit elev. 5279 m

Servicio Geológico Colombiano’s (SGC) Observatorio Vulcanológico y Sismológico de Manizales reported that during 2-8 August seismicity at Nevado del Ruiz remained at similar levels as the week before. Significant amounts of water vapor and gas rose from the crater. A gas, steam, and ash plume rose 850 m above the crater rim and drifted NW and W on 6 August. The Alert Level remained at III (Yellow; the second lowest level on a four-color scale).

Geological summary: Nevado del Ruiz is a broad, glacier-covered volcano in central Colombia that covers >200 sq km. Three major edifices, composed of andesitic and dacitic lavas and andesitic pyroclastics, have been constructed since the beginning of the Pleistocene. The modern cone consists of a broad cluster of lava domes built within the caldera of an older edifice. The 1-km-wide, 240-m-deep Arenas crater occupies the summit. The prominent La Olleta pyroclastic cone located on the SW flank may also have been active in historical time. Steep headwalls of massive landslides cut the flanks. Melting of its summit icecap during historical eruptions, which date back to the 16th century, has resulted in devastating lahars, including one in 1985 that was South America's deadliest eruption.

Nevados de Chillán, Chile
36.863°S, 71.377°W, Summit elev. 3212 m

Servicio Nacional de Geología and Minería (SERNAGEOMIN) Observatorio Volcanológico de Los Andes del Sur (OVDAS) reported that the seismic stations monitoring Nevados de Chillán recorded an increase in seismic signals indicating explosions and increased emissions from new craters on the E side of Volcán Nuevo and the Volcán Arrau dome complex. During 1-9 August there were 11 explosions detected; the highest energy signal was recorded at 1656 on 8 August and was accompanied by an emission that rose 2 km. That same day the Buenos Aires VAAC reported that a gas-and-ash puff rose to an altitude of 4.2 km (14,000 ft) a.s.l. The Alert Level remained at Yellow, the middle level on a three-color scale, and the public was reminded not to approach the craters within a 3-km radius which had been extended due to the recent activity increase.

Geological summary: The compound volcano of Nevados de Chillán is one of the most active of the Central Andes of Chile. Three late-Pleistocene to Holocene stratovolcanoes were constructed along a NNW-SSE line within three nested Pleistocene calderas, which produced ignimbrite sheets extending more than 100 km into the Central Depression of Chile. The largest stratovolcano, dominantly andesitic, 3212-m-high Cerro Blanco (Volcán Nevado), is located at the NW end of the group, and 3089-m-high Volcán Viejo (Volcán Chillán), which was the main active vent during the 17th-19th centuries, occupies the SE end. The new Volcán Nuevo lava-dome complex formed between 1906 and 1945 between the two volcanoes and grew to exceed Volcán Viejo in altitude. The Volcán Arrau dome complex was constructed SE of Volcán Nuevo between 1973 and 1986, eventually exceeding its height by 20 m.

Pavlof, United States
55.417°N, 161.894°W, Summit elev. 2493 m

AVO reported that since an ash-and-steam explosion at Pavlof on 27 July, activity had continued to decline. On 4 August AVO lowered the Aviation Color Code to Yellow and the Volcano Alert Level to Advisory. During 5-9 August seismicity remained low but above background levels. Elevated surface temperatures were observed in one nighttime satellite image during 7-8 August.

Geological summary: The most active volcano of the Aleutian arc, Pavlof is a 2519-m-high Holocene stratovolcano that was constructed along a line of vents extending NE from the Emmons Lake caldera. Pavlof and its twin volcano to the NE, 2142-m-high Pavlof Sister, form a dramatic pair of symmetrical, glacier-covered stratovolcanoes that tower above Pavlof and Volcano bays. A third cone, Little Pavlof, is a smaller volcano on the SW flank of Pavlof volcano, near the rim of Emmons Lake caldera. Unlike Pavlof Sister, Pavlof has been frequently active in historical time, typically producing Strombolian to Vulcanian explosive eruptions from the summit vents and occasional lava flows. The active vents lie near the summit on the north and east sides. The largest historical eruption took place in 1911, at the end of a 5-year-long eruptive episode, when a fissure opened on the N flank, ejecting large blocks and issuing lava flows.

Reventador, Ecuador
0.077°S, 77.656°W, Summit elev. 3562 m

During 3-9 August IG reported a high level of seismic activity including explosions, long-period earthquakes, harmonic tremor, and signals indicating emissions at Reventador; cloud cover sometimes prevented visual observations. Incandescent blocks rolled as far as 1 km down the flanks. Gas, water vapor, and ash plumes rose from the crater during 3-4 and 6-7 August; the plumes rose as high as 1 km on 6 August.

Geological summary: Reventador is the most frequently active of a chain of Ecuadorian volcanoes in the Cordillera Real, well east of the principal volcanic axis. The forested, dominantly andesitic Volcán El Reventador stratovolcano rises to 3562 m above the jungles of the western Amazon basin. A 4-km-wide caldera widely breached to the east was formed by edifice collapse and is partially filled by a young, unvegetated stratovolcano that rises about 1300 m above the caldera floor to a height comparable to the caldera rim. It has been the source of numerous lava flows as well as explosive eruptions that were visible from Quito in historical time. Frequent lahars in this region of heavy rainfall have constructed a debris plain on the eastern floor of the caldera. The largest historical eruption took place in 2002, producing a 17-km-high eruption column, pyroclastic flows that traveled up to 8 km, and lava flows from summit and flank vents.

Santa Maria, Guatemala
14.756°N, 91.552°W, Summit elev. 3772 m

INSIVUMEH reported that on 8 August an 18-m-wide hot lahar triggered by rainfall descended the Cabello de Ángel drainage, a tributary of the Nimá I river drainage on the S flank of Santa María’s Santiaguito lava-dome complex, carrying tree trunks and blocks up to 1.5 cm in diameter. Explosions during 8-9 August produced ash plumes that rose as high as 1 km above the crater and drifted 15 km SW, W, and NW.

Geological summary: Symmetrical, forest-covered Santa María volcano is one of the most prominent of a chain of large stratovolcanoes that rises dramatically above the Pacific coastal plain of Guatemala. The 3772-m-high stratovolcano has a sharp-topped, conical profile that is cut on the SW flank by a large, 1.5-km-wide crater. The oval-shaped crater extends from just below the summit to the lower flank and was formed during a catastrophic eruption in 1902. The renowned plinian eruption of 1902 that devastated much of SW Guatemala followed a long repose period after construction of the large basaltic-andesite stratovolcano. The massive dacitic Santiaguito lava-dome complex has been growing at the base of the 1902 crater since 1922. Compound dome growth at Santiaguito has occurred episodically from four westward-younging vents, the most recent of which is Caliente. Dome growth has been accompanied by almost continuous minor explosions, with periodic lava extrusion, larger explosions, pyroclastic flows, and lahars.

Sheveluch, Central Kamchatka (Russia)
56.653°N, 161.36°E, Summit elev. 3283 m

KVERT reported that during 29 July-5 August lava-dome extrusion onto Sheveluch’s N flank was accompanied by strong fumarolic activity, dome incandescence, ash explosions, and hot avalanches. Satellite images showed a daily thermal anomaly over the dome. The Aviation Color Code remained at Orange.

Geological summary: The high, isolated massif of Sheveluch volcano (also spelled Shiveluch) rises above the lowlands NNE of the Kliuchevskaya volcano group. The 1300 cu km volcano is one of Kamchatka's largest and most active volcanic structures. The summit of roughly 65,000-year-old Stary Shiveluch is truncated by a broad 9-km-wide late-Pleistocene caldera breached to the south. Many lava domes dot its outer flanks. The Molodoy Shiveluch lava dome complex was constructed during the Holocene within the large horseshoe-shaped caldera; Holocene lava dome extrusion also took place on the flanks of Stary Shiveluch. At least 60 large eruptions have occurred during the Holocene, making it the most vigorous andesitic volcano of the Kuril-Kamchatka arc. Widespread tephra layers from these eruptions have provided valuable time markers for dating volcanic events in Kamchatka. Frequent collapses of dome complexes, most recently in 1964, have produced debris avalanches whose deposits cover much of the floor of the breached caldera.

Sinabung, Indonesia
3.17°N, 98.392°E, Summit elev. 2460 m

Based on satellite images, model data, ground reports from PVMBG, and the Jakarta MWO, the Darwin VAAC reported that during 3-5 and 7 August ash plumes from Sinabung rose to altitudes of 3.7-5.5 km (12,000-18,000 ft) a.s.l. and drifted SE, NE, and NNW.

Geological summary: Gunung Sinabung is a Pleistocene-to-Holocene stratovolcano with many lava flows on its flanks. The migration of summit vents along a N-S line gives the summit crater complex an elongated form. The youngest crater of this conical, 2460-m-high andesitic-to-dacitic volcano is at the southern end of the four overlapping summit craters. An unconfirmed eruption was noted in 1881, and solfataric activity was seen at the summit and upper flanks in 1912. No confirmed historical eruptions were recorded prior to explosive eruptions during August-September 2010 that produced ash plumes to 5 km above the summit.

Yasur, Vanuatu
19.53°S, 169.442°E, Summit elev. 361 m

On 2 August the Vanuatu Geohazards Observatory stated that the Alert Level for Yasur remained at 2 (on a scale of 0-4) and that explosions continued to be intense. VGO reminded residents and tourists that hazardous areas were near and around the volcanic crater, within a 600-m-radius permanent exclusion zone, and that volcanic ash and gas could reach areas impacted by trade winds.

Geological summary: Yasur, the best-known and most frequently visited of the Vanuatu volcanoes, has been in more-or-less continuous strombolian and vulcanian activity since Captain Cook observed ash eruptions in 1774. This style of activity may have continued for the past 800 years. Located at the SE tip of Tanna Island, this mostly unvegetated pyroclastic cone has a nearly circular, 400-m-wide summit crater. Yasur is largely contained within the small Yenkahe caldera and is the youngest of a group of Holocene volcanic centers constructed over the down-dropped NE flank of the Pleistocene Tukosmeru volcano. The Yenkahe horst is located within the Siwi ring fracture, a 4-km-wide, horseshoe-shaped caldera associated with eruption of the andesitic Siwi pyroclastic sequence. Active tectonism along the Yenkahe horst accompanying eruptions has raised Port Resolution harbor more than 20 m during the past century.

Source: GVP

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