PLANET X UPDATE:
The Beginning of a Plateau?
Nothing has changed significantly in February, except for the hope of good news as there has not been much of that lately. However, there may be the possibility that the overall slowing of trend data we began seeing earlier this year. If so we ask, could we see the beginning of a plateau?
We’ll address this question later on, but for now, let’s see how fireball and earthquake trends for February 2018 stack up.
February 2018 Fireballs
Fireballs are reported worldwide, and the American
Meteor Society which is the primary source for North America, for this
dataset.
AMS Multistate / Country Fireballs
Multistate/country fireballs, cross the borders of
multiple states and countries. For this reason, this is a critical
category in the dataset because of the distance these fireballs must
travel to be reported across large geographic areas.
Given that February 2018 is slightly lower than
February 2017 but still higher than February 2015 and 2016, there is no
significant change in this dataset category.
AMS Huge Event Fireballs
It is a commonplace occurrence for Multistate /
Country Fireballs to be reported as huge events because a huge event
occurs when fireball reports are received from 100 or more eyewitness
observers.
Except February 2016, the number of huge event
fireballs in February 2018 is equal to or higher than all previous month
for January and February for 2015 through 2018. Again, no significant
change in this dataset category.
AMS Monthly Total Fireballs
The monthly total fireballs are the most critical
category in this dataset. When we look at the monthly total of fireballs
for this five-year study dating back to 2015, we wee that January 2018
represents an all-time high for this month.
February 2018 is slightly less than February 2016 and
2017. Although there is no significant change in this dataset category,
the variance pattern does raise an interesting question. Will we see a
possible plateau? If so, it will take another two or three months to
tell.
AMS Total Yearly Fireballs
The dataset for total yearly fireballs has changed
from 2009 through 2017 as shown in Signs 21, to 2011 to 2018. As
reported in Signs 20 is shown again below.
By May of this year, the total yearly fireballs for
2018 should be comparable to 2011, however, as of February 2018, the
total yearly fireballs for 2018 is roughly the same as 2009. Therefore,
the overall trend is continuing but escalating at a much slower rate
than in previous years.
Earthquakes Since 1997
At the outset of our Signs series, J. P. Jones
created a dataset spreadsheet that tracks the total number of
earthquakes each month beginning with 1997. The updated spreadsheet
below has been updated with the February 2018 results.
With earthquakes for February 2018, we see a reverse
image of the AMS monthly total fireballs for February 2018. What we are
seeing is that fireballs for February are slightly less than the
previous two years for the same month. However, with earthquakes, the
reverse is true. February 2018 is slightly higher than the previous two
years for the same month.
Global Earthquakes of all Magnitudes Jan 2015 to Jan 2018
When we look at annual global earthquakes for all
magnitudes for the period January 2015 to February 2018, the overall
trend indicates a slow rate of growth.
The next few months will be interesting to watch,
especially with all of the volcanic eruptions taking place now. If over
the next few months, the trends we’re monitoring with this series could
move us towards a plateau. What does that mean? A simple choice – apathy
or vigilance. And with that, we look forward to seeing the numbers for
March when they come in.
The Weekly Volcanic Activity Report: March 7 - 13, 2018
New activity/unrest: Kick 'em Jenny, North of Grenada | Kirishimayama, Kyushu (Japan) | Turrialba, Costa Rica.
Ongoing activity: Agung, Bali (Indonesia) | Aira, Kyushu (Japan) | Ambae, Vanuatu | Cleveland, Chuginadak Island (USA) | Dukono, Halmahera (Indonesia) | Ebeko, Paramushir Island (Russia) | Ibu, Halmahera (Indonesia) | Kadovar, Papua New Guinea | Kilauea, Hawaiian Islands (USA) | Mayon, Luzon (Philippines) | Nevados de Chillan, Chile | Popocatepetl, Mexico | Reventador, Ecuador | Sabancaya, Peru | Sheveluch, Central Kamchatka (Russia).
The Weekly Volcanic Activity Report is a cooperative project between the Smithsonian's Global Volcanism Program and the US Geological Survey's Volcano Hazards Program. Updated by 23:00 UTC every Wednesday, notices of volcanic activity posted are preliminary and subject to change as events are studied in more detail. This is not a comprehensive list of all of Earth's volcanoes erupting during the week. Carefully reviewed, detailed reports on various volcanoes are published monthly in the Bulletin of the Global Volcanism Network.
New activity/unrest
Kick 'em Jenny, North of Grenada
12.3°N, 61.64°W, Summit elev. -185 mThe University of the West Indies (UWI) Seismic Research Centre (SRC) and the National Disaster Management Agency (NaDMA) reported that on 12 March the Alert Level for Kick 'em Jenny was raised to Orange (the second highest level on a four-color scale) due to non-specified increased activity. The report reminded marine operators of the 5-km maritime exclusion zone.
Geologic summary: Kick 'em Jenny, a historically active submarine volcano 8 km off the N shore of Grenada, rises 1300 m from the sea floor. Recent bathymetric surveys have shown evidence for a major arcuate collapse structure, which was the source of a submarine debris avalanche that traveled more than 15 km W. Bathymetry also revealed another submarine cone to the SE, Kick 'em Jack, and submarine lava domes to its S. These and subaerial tuff rings and lava flows at Ile de Caille and other nearby islands may represent a single large volcanic complex. Numerous historical eruptions, mostly documented by acoustic signals, have occurred since 1939, when an eruption cloud rose 275 m above the sea. Prior to the 1939 eruption, which was witnessed by a large number of people in northern Grenada, there had been no written mention of the volcano. Eruptions have involved both explosive activity and the quiet extrusion of lava flows and lava domes in the summit crater; deep rumbling noises have sometimes been heard onshore. Historical eruptions have modified the morphology of the summit crater.
Kirishimayama, Kyushu (Japan)
31.934°N, 130.862°E, Summit elev. 1700 mAccording to news articles, ash plumes from Shinmoedake (Shinmoe peak), a stratovolcano of the Kirishimayama volcano group, caused the cancelation of about 80 flights in and out of Kagoshima airport on 6 March. JMA reported that daily explosions during 6-13 March generated ash plumes that generally rose 3 km above the crater rim, though an ash plume on 10 March rose as high as 4.5 km. Explosions also ejected tephra that fell 700-1,800 m from the vent. Ashfall was reported in a wide area including in the prefectures of Nagasaki, Kumamoto, Miyazaki, and Kagoshima. An explosion at 1558 on 9 March rattled structures in the Kagoshima and Miyazaki prefectures. Satellite images showed an increase in the crater diameter from 550 m on 7 March to 650 m on 9 March. During overflights on 9 March observers noted white plumes rising from the margins of the lava covering the crater floor, from lava flows on the S flank, and from newly forming lava flows on the NW flank. The volume of erupted lava was an estimated 14 million cubic meters. The NW lava flow had advanced 226 m by 13 March. A high number of volcanic earthquakes continued to be recorded, in addition to many low-frequency earthquakes with shallow hypocenters. Volcanic tremor was continuous from 1 March until 1536 on 8 March; afterwards the signals had small amplitudes and were intermittent. The Alert Level remained at 3 (on a scale of 1-5).
Geologic summary: Kirishimayama is a large group of more than 20 Quaternary volcanoes located north of Kagoshima Bay. The late-Pleistocene to Holocene dominantly andesitic group consists of stratovolcanoes, pyroclastic cones, maars, and underlying shield volcanoes located over an area of 20 x 30 km. The larger stratovolcanoes are scattered throughout the field, with the centrally located, 1700-m-high Karakunidake being the highest. Onamiike and Miike, the two largest maars, are located SW of Karakunidake and at its far eastern end, respectively. Holocene eruptions have been concentrated along an E-W line of vents from Miike to Ohachi, and at Shinmoedake to the NE. Frequent small-to-moderate explosive eruptions have been recorded since the 8th century.
Turrialba, Costa Rica
10.025°N, 83.767°W, Summit elev. 3340 mRSN and OVSICORI-UNA reported that a new eruptive phase at Turrialba began at 2240 on 6 March with minor ash emissions that rose 500 m above the vent rim and drifted NW. The activity intensified around midnight, with dense ash emissions and the ejection of incandescent blocks, and remained elevated almost until 0300 on 7 March. At 1740 activity again intensified; emissions with an increased volume of ash was recorded by the webcam from 1801-1820 drifting W. OVSICORI-UNA reported that events at 1515 on 8 March and 0920 on 13 March generated ash plumes that rose 300 m and drifted SW and NW, respectively.
Geologic summary: Turrialba, the easternmost of Costa Rica's Holocene volcanoes, is a large vegetated basaltic-to-dacitic stratovolcano located across a broad saddle NE of Irazú volcano overlooking the city of Cartago. The massive edifice covers an area of 500 km2. Three well-defined craters occur at the upper SW end of a broad 800 x 2200 m summit depression that is breached to the NE. Most activity originated from the summit vent complex, but two pyroclastic cones are located on the SW flank. Five major explosive eruptions have occurred during the past 3500 years. A series of explosive eruptions during the 19th century were sometimes accompanied by pyroclastic flows. Fumarolic activity continues at the central and SW summit craters.
Ongoing activity
Agung, Bali (Indonesia)
8.343°S, 115.508°E, Summit elev. 2997 mPVMBG reported that although there were sometimes foggy conditions during 7-13 March, white plumes were observed rising as high as 600 m above Agung’s crater rim and drifting E. An event at 2332 on 11 March generated an ash plume that rose about 950 m and drifted E. The Alert Level remained at 3 (on a scale of 1-4) and the exclusion zone continued at a 4-km radius.
Geologic summary: Symmetrical Agung stratovolcano, Bali's highest and most sacred mountain, towers over the eastern end of the island. The volcano, whose name means "Paramount," rises above the SE caldera rim of neighboring Batur volcano, and the northern and southern flanks extend to the coast. The summit area extends 1.5 km E-W, with the high point on the W and a steep-walled 800-m-wide crater on the E. The Pawon cone is located low on the SE flank. Only a few eruptions dating back to the early 19th century have been recorded in historical time. The 1963-64 eruption, one of the largest in the 20th century, produced voluminous ashfall along with devastating pyroclastic flows and lahars that caused extensive damage and many fatalities.
Aira, Kyushu (Japan)
31.593°N, 130.657°E, Summit elev. 1117 mJMA reported that on 5 March at 2026 an event at Minamidake crater (at Aira Caldera’s Sakurajima volcano) produced an ash plume that rose 1 km above the crater rim, into the clouds. Two explosions were detected on 10 March; one of the events, at 2312, generated ash plumes that rose 1.5 km above the crater rim and ejected material as far as 1.3 km. The Alert Level remained at 3 (on a 5-level scale).
Geologic 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.
Ambae, Vanuatu
15.4°S, 167.83°E, Summit elev. 1496 mBased on satellite and webcam observations, and model data, the Wellington VAAC reported that during 12-13 March ash plumes from Ambae rose to an altitude of 3 km (10,000 ft) a.s.l. and drifted SW.
Geologic summary: Ambae, also known as Aoba, is a massive 2500 km3 basaltic shield that is the most voluminous volcano of the New Hebrides archipelago. A pronounced NE-SW-trending rift zone dotted with scoria cones gives the 16 x 38 km island an elongated form. A broad pyroclastic cone containing three crater lakes is located at the summit within the youngest of at least two nested calderas, the largest of which is 6 km in diameter. Post-caldera explosive eruptions formed the summit craters of Lake Voui (also spelled Vui) and Lake Manaro Ngoru about 360 years ago. A tuff cone was constructed within Lake Voui about 60 years later. The latest known flank eruption, about 300 years ago, destroyed the population of the Nduindui area near the western coast.
Cleveland, Chuginadak Island (USA)
52.825°N, 169.944°W, Summit elev. 1730 mAVO reported that unrest continued at Cleveland during 7-13 March. Elevated surface temperatures were identified in satellite images on 7 March and seismicity slightly increased on 8 March. The Aviation Color Code was lowered to Yellow and the Volcano Alert Level was lowered to Advisory.
Geologic summary: The beautifully symmetrical Mount Cleveland stratovolcano is situated at the western end of the uninhabited, dumbbell-shaped Chuginadak Island. It lies SE across Carlisle Pass strait from Carlisle volcano and NE across Chuginadak Pass strait from Herbert volcano. Joined to the rest of Chuginadak Island by a low isthmus, Cleveland is the highest of the Islands of the Four Mountains group and is one of the most active of the Aleutian Islands. The native name, Chuginadak, refers to the Aleut goddess of fire, who was thought to reside on the volcano. Numerous large lava flows descend the steep-sided flanks. It is possible that some 18th-to-19th century eruptions attributed to Carlisle should be ascribed to Cleveland (Miller et al., 1998). In 1944 Cleveland produced the only known fatality from an Aleutian eruption. Recent eruptions have been characterized by short-lived explosive ash emissions, at times accompanied by lava fountaining and lava flows down the flanks.
Dukono, Halmahera (Indonesia)
1.693°N, 127.894°E, Summit elev. 1229 mBased on analyses of satellite imagery and wind model data, the Darwin VAAC reported that during 7-13 March ash plumes from Dukono rose to altitudes of 1.5-3 km (5,000-10,000 ft) a.s.l. and drifted in multiple directions.
Geologic 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.
Ebeko, Paramushir Island (Russia)
50.686°N, 156.014°E, Summit elev. 1103 mBased on observations by volcanologists in Severo-Kurilsk (Paramushir Island), about 7 km E of Ebeko, explosions on 6 March generated ash plumes that rose as high as 1.7 km (5,600 ft) a.s.l. The Aviation Color Code remained at Orange (the second highest level on a four-color scale).
Geologic summary: The flat-topped summit of the central cone of Ebeko volcano, one of the most active in the Kuril Islands, occupies the northern end of Paramushir Island. Three summit craters located along a SSW-NNE line form Ebeko volcano proper, at the northern end of a complex of five volcanic cones. Blocky lava flows extend west from Ebeko and SE from the neighboring Nezametnyi cone. The eastern part of the southern crater contains strong solfataras and a large boiling spring. The central crater is filled by a lake about 20 m deep whose shores are lined with steaming solfataras; the northern crater lies across a narrow, low barrier from the central crater and contains a small, cold crescentic lake. Historical activity, recorded since the late-18th century, has been restricted to small-to-moderate explosive eruptions from the summit craters. Intense fumarolic activity occurs in the summit craters, on the outer flanks of the cone, and in lateral explosion craters.
Ibu, Halmahera (Indonesia)
1.488°N, 127.63°E, Summit elev. 1325 mPVMBG reported that although foggy conditions often prevailed at Ibu ash plumes were observed rising 300-600 m above the carter rim and drifting W and S. The Alert Level remained at 2 (on a scale of 1-4), and the public was warned to stay at least 2 km away from the active crater, and 3.5 km away on the N side.
Geologic summary: The truncated summit of Gunung Ibu stratovolcano along the NW coast of Halmahera Island has large nested summit craters. The inner crater, 1 km wide and 400 m deep, contained several small crater lakes through much of historical time. The outer crater, 1.2 km wide, is breached on the north side, creating a steep-walled valley. A large parasitic cone is located ENE of the summit. A smaller one to the WSW has fed a lava flow down the W flank. A group of maars is located below the N and W flanks. Only a few eruptions have been recorded in historical time, the first a small explosive eruption from the summit crater in 1911. An eruption producing a lava dome that eventually covered much of the floor of the inner summit crater began in December 1998.
Kadovar, Papua New Guinea
3.608°S, 144.588°E, Summit elev. 365 mRVO reported that emissions from Kadovar’s Main Crater were white from 1 March, until an explosion on 1800 on 5 March was followed by gray emissions through 8 March. The gray plumes rose less than 360 m above the vent and drifted SE. Noises were described as roaring and rumbling during 1-2 and 6-8 March, and booming on 5 March. The lava dome at the SE Coastal Vent continued to grow and rose to 7-8 m above sea level on 1 March, 10-11 m on 2 March, and 10-17 m on 8 March. Dark gray ash plumes rose from the dome. Nighttime incandescence was noted from both Main Crater and the SE vent.
Geologic summary: The 2-km-wide island of Kadovar is the emergent summit of a Bismarck Sea stratovolcano of Holocene age. Kadovar is part of the Schouten Islands, and lies off the coast of New Guinea, about 25 km N of the mouth of the Sepik River. The village of Gewai is perched on the crater rim. A 365-m-high lava dome forming the high point of the andesitic volcano fills an arcuate landslide scarp that is open to the south, and submarine debris-avalanche deposits occur in that direction. Thick lava flows with columnar jointing forms low cliffs along the coast. The youthful island lacks fringing or offshore reefs. No certain historical eruptions are known; the latest activity was a period of heightened thermal phenomena in 1976.
Kilauea, Hawaiian Islands (USA)
19.421°N, 155.287°W, Summit elev. 1222 mDuring 7-13 March HVO reported that the lava lake continued to rise, fall, and spatter in Kilauea’s Overlook crater. Webcams recorded incandescence from a small lava pond in a pit on the W side of Pu'u 'O'o Crater. Surface lava flows were active above and on Pulama pali.
Geologic summary: Kilauea, which overlaps the E 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 km2, destroying nearly 200 houses and adding new coastline to the island.
Mayon, Luzon (Philippines)
13.257°N, 123.685°E, Summit elev. 2462 mPHIVOLCS reported that during 6-13 March activity at Mayon was characterized by periods of gravity-driven lava advancement, gas-and-steam emissions, lava fountains, and quiescence. Episodes of weak lava fountaining during 6-10 March were accompanied by ash plumes that rose 100-300 m above the crater and drifted mainly SW. Rumbling sounds were audible at least within a 10-km radius. Active lava flows extended 3.3 km, 4.5 km, and 1.9 km long in the Mi-isi (S), Bonga (SE), and Basud (E) drainages, respectively. Steam plumes rose 2.4 km and drifted SW on 10 March. The next day white-and-gray plumes rose 2.5 km and drifted SW. The Alert Level remained at 3 (on a 0-5 scale) and PHIVOLCS reminded residents to stay away from the 6-km-radius Permanent Danger Zone and the 7-km Extended Danger Zone on the SSW and ENE flanks.
Geologic summary: Beautifully symmetrical Mayon, which rises above the Albay Gulf NW of Legazpi City, is the Philippines' most active volcano. The structurally simple edifice has steep upper slopes averaging 35-40 degrees that are capped by a small summit crater. Historical eruptions date back to 1616 and range from Strombolian to basaltic Plinian, with cyclical activity beginning with basaltic eruptions, followed by longer term andesitic lava flows. Eruptions occur predominately from the central conduit and have also produced lava flows that travel far down the flanks. Pyroclastic flows and mudflows have commonly swept down many of the approximately 40 ravines that radiate from the summit and have often devastated populated lowland areas. A violent eruption in 1814 killed more than 1,200 people and devastated several towns.
Nevados de Chillan, Chile
36.868°S, 71.378°W, Summit elev. 3180 mServicio Nacional de Geología and Minería (SERNAGEOMIN) Observatorio Volcanológico de Los Andes del Sur (OVDAS) reported continuing activity during 16-28 February associated with a low rate of growth of the Gil-Cruz lava dome in Nevados de Chillán’s Nicanor Crater. Continuous gas emissions from the SE-NW-trending fissure on the dome’s surface were punctuated by emission of ash and water vapor that rose no higher than 1.8 km. During an overflight on 22 February observers noted an increased volume of the dome compared to the previous observation. 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 4-km radius.
Geologic summary: The compound volcano of Nevados de Chillán is one of the most active of the Central Andes. 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, Cerro Blanco (Volcán Nevado), is located at the NW end of the group. 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 elevation. The Volcán Arrau dome complex was constructed SE of Volcán Nuevo between 1973 and 1986 and eventually exceeded its height.
Popocatepetl, Mexico
19.023°N, 98.622°W, Summit elev. 5393 mCENAPRED reported that each day during 7-13 March there were 105-361 steam and gas emissions from Popocatépetl. Incandescence from the crater was visible at night. Explosions were recorded on 7 March. An explosion at 1042 on 12 March generated an ash plume that rose 1.5 km above the crater rim and drifted SE. The Alert Level remained at Yellow, Phase Two.
Geologic summary: Volcán Popocatépetl, whose name is the Aztec word for smoking mountain, rises 70 km SE of Mexico City to form North America's 2nd-highest volcano. The glacier-clad stratovolcano contains a steep-walled, 400 x 600 m wide crater. The generally symmetrical volcano is modified by the sharp-peaked Ventorrillo on the NW, a remnant of an earlier volcano. At least three previous major cones were destroyed by gravitational failure during the Pleistocene, producing massive debris-avalanche deposits covering broad areas to the south. The modern volcano was constructed south of the late-Pleistocene to Holocene El Fraile cone. Three major Plinian eruptions, the most recent of which took place about 800 CE, have occurred since the mid-Holocene, accompanied by pyroclastic flows and voluminous lahars that swept basins below the volcano. Frequent historical eruptions, first recorded in Aztec codices, have occurred since Pre-Columbian time.
Reventador, Ecuador
0.077°S, 77.656°W, Summit elev. 3562 mDuring 6-13 March IG reported a high level of seismic activity including explosions, long-period earthquakes, harmonic tremor, and signals indicating emissions at Reventador. Steam, gas, and ash plumes sometimes rose higher than 600 m above the crater rim and drifted N, NW, and W. Incandescent blocks rolled as far as 800 m down the flanks. On 13 March a pyroclastic flow traveled 400 m down the S flank. Weather clouds sometimes prevented visual observations.
Geologic 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.
Sabancaya, Peru
15.787°S, 71.857°W, Summit elev. 5960 mObservatorio Vulcanológico del Sur del IGP (OVS-IGP) and Observatorio Vulcanológico del INGEMMET (OVI) reported that explosive activity at Sabancaya decreased compared to the previous week; explosions averaged 10 per day during 5-11 March. Seismicity was dominated by long-period events, with signals indicating emissions. Gas-and-ash plumes rose 5.4 km above the crater rim and drifted 30 km N, NW, W, and SW. The sulfur dioxide flux was high, at 2,396 tons per day on 9 March. The report noted that the public should not to approach the crater within a 12-km radius.
Geologic summary: Sabancaya, located in the saddle NE of Ampato and SE of Hualca Hualca volcanoes, is the youngest of these volcanic centers and the only one to have erupted in historical time. The oldest of the three, Nevado Hualca Hualca, is of probable late-Pliocene to early Pleistocene age. The name Sabancaya (meaning "tongue of fire" in the Quechua language) first appeared in records in 1595 CE, suggesting activity prior to that date. Holocene activity has consisted of Plinian eruptions followed by emission of voluminous andesitic and dacitic lava flows, which form an extensive apron around the volcano on all sides but the south. Records of historical eruptions date back to 1750.
Sheveluch, Central Kamchatka (Russia)
56.653°N, 161.36°E, Summit elev. 3283 mKVERT reported that a weak thermal anomaly over Sheveluch was identified in satellite images on 4 and 6-8 March. The Aviation Color Code remained at Orange.
Geologic summary: The high, isolated massif of Sheveluch volcano (also spelled Shiveluch) rises above the lowlands NNE of the Kliuchevskaya volcano group. The 1300 km3 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.
