On the other hand, the shallow tremors have decreased to about one-quarter of their rate of occurrence in early December, without any decline having taken place in the rate of injection of new lava into the dome. info@greenfigresort.com reservations@greenfigresort.com Tel. Between surveys on 2 July and 4 August, the lava had expanded 30-50 m horizontally (except on the N side where it had reached the crater wall, 4:6) and about 6 m vertically, to a mean diameter of 820 m and a mean height of 85 m. Assuming 45 sides, its volume was 36.5 x 106 m3 on 4 August, having increased an average of 0.36 x 106 m3/day in July (similar to the June rate). Measurements have been made on near-vertical air photos of the crater taken on 11 February and kindly placed at our disposal by Mrs. M. Barnard. The first historical eruption took place in 1718; it and the 1812 eruption produced major explosions. Table 6. Courtesy of the Seismic Research Unit. These are samples of plagioclase-phyric dark gray basaltic andesite with sparse phenocrysts of olivine and pyroxene. By Robin George Andrews Published April 9, 2021 10 min read Geotherm. On 19 March the dome was 105 m tall, 921 m long, and 243 m wide, with an estimated volume of 13.13 million cubic meters, based on drone surveys (figure 18). To convert, we can use a factor of 2. Confirmed Eruption, 2200 BCE 150 years This compilation of synonyms and subsidiary features may not be comprehensive. However, the rate of extrusion continued to decrease; the late August-late September rate was an order of magnitude less than peak values observed in mid-May. Catalog number links will open a window with more information. The maximum depth in this area is 111 feet. The increased scent of sulfur in towns was attributed to a southward shift in wind direction towards the towns, rather than the usual E direction. Information Contacts: Card 1350 (03 February 1972) John F. Tomblin, Seismic Research Unit, University of the West Indies. Nature, 282 (5734), 2428. The rates of those events dropped again, at around 0100 on 19 April. La Fortuna - Arenal. Courtesy of the Seismic Research Unit. This island consists of angular blocks 1-10 m across and appears to be the top of a lava dome standing 200 m above the former lake floor. University of the West Indies Seismic Research Centre (UWI-SRC) and National Emergency Management Organisation (NEMO) reported that the lava dome in Soufrire St. Vincents main crater continued to grow during 24 February-2 March. Later that evening, incandescent material over the vent area was visible in webcam images, and views from the observatory indicated that the dome had grown significantly. After this explosion, the seismicity consisted primarily of 30-50 small explosion events per hour, which could be correlated with the ejection of steam puffs that sometimes contained a little ash. The maximum water depth recorded was 99.5 ft, at a point approximately halfway between the island and the lake edge. Basse-Terre North. Work on the construction of a tiltmeter station at Orange Hill is now completed. Remarks: Rapid deflation of more than 20 microradians occurred during the eruption. This may be a local phenomenon, due to relatively small output of lava into the southern part of the lake in the last few days, and we believe that other inaccessible regions of the lake are hotter. University of the West Indies Seismic Research Centre (UWI-SRC) and National Emergency Management Organisation (NEMO) reported that the lava dome in Soufrire St. Vincents main crater continued to slowly grow during 23-27 March, expanding to the N and S. Gas-and-steam continued to rise from the top of the dome, as well as along the contact with the pre-existing 1979 dome. There has been no significant change in seismicity since a several-day increase in the number of events in late June and early July. The noon explosion on 14 April produced a 100 km-diameter cloud, and two explosions on 13 April also produced sizeable clouds, 60-km-diameter at 1700 and 40 km at 2050. Play. Information Contacts: Richard Robertson, Seismic Research Unit, The University of the West Indies, St. Augustine, Trinidad (URL: http://www.uwiseismic.com/); Aisha Samuel, Soufriere Monitoring Unit, Ministry of Agriculture, St. Vincent. The first pre-eruption seismic event, telemetered to the Seismic Research Unit of the University of the West Indies by seismometers 3 and 9 km from Soufrire's summit, was a strong local earthquake at 1106 on 12 April, within 1 hour of the fortnightly earth tide maximum (calculated by F.J. Mauk). Visual observations and timing of events and processes on the island have permitted correlation of some of the larger tremors with rockfall and lava creep. The number of individual events declined irregularly through the morning of 16 April. A diffuse steam plume rose from the crater on 24 April. A change in character of an eruption like this is not uncommon. of Hawai'i, 2525 Correa Road, Honolulu, HI 96822, USA (URL: http://modis.higp.hawaii.edu/); NASA Global Sulfur Dioxide Monitoring Page, Atmospheric Chemistry and Dynamics Laboratory, NASA Goddard Space Flight Center (NASA/GSFC), 8800 Greenbelt Road, Goddard, Maryland, USA (URL: https://so2.gsfc.nasa.gov/); MIROVA (Middle InfraRed Observation of Volcanic Activity), a collaborative project between the Universities of Turin and Florence (Italy) supported by the Centre for Volcanic Risk of the Italian Civil Protection Department (URL: http://www.mirovaweb.it/); Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground); Jenni Barclay, University of East Anglia, Norwich Research Park, Norwich, Norfolk, NR4 7TJ, UK (URL: https://research-portal.uea.ac.uk/en/persons/jenni-barclay); Ian Renfrew, University of East Anglia, Norwich Research Park, Norwich, Norfolk, NR4 7TJ, UK (URL: https://research-portal.uea.ac.uk/en/persons/ian-renfrew). Lava extrusion continued from the same vent that produced the 1971 dome and the 1979 explosions. Island growth continues; historical comparisons, Card 1350 (03 February 1972) Analyses of volcanic products. Information Contacts: Card 1388 (02 May 1972) J.B. Shepherd and W.P. Max VEI: 0, 1902 May 6 - 1903 Mar 30 Then, at 8:51 a.m. on April 9, the National Emergency Management announced La Soufrire had erupted. A change in character of an eruption like this is not uncommon. Few, but intermittent, rockfall events, VT earthquakes, and an increasing number of small LP and hybrid earthquakes were detected through 21 April (see figure 26). It appears that La Soufrire on St. Vincent has taken a decidely more explosive turn. Explosions early on 11 April were followed by widespread power and water outages on the island as reported by NEMO, and some houses had collapsed under the significant ashfall. When one is found the date, time, location, and intensity are recorded. Confirmed Eruption, 0530 BCE 75 years No lava has been extruded into Soufrire's central crater since the survey of 25 October. Activity during March 2021. UWI-SRC and the National Emergency Management Organisation (NEMO) both warned the public to stay away from drainages and areas prone to flooding, and noted that lahars have caused notable erosion and damage to drainages and parts of the coastline. Information Contacts: University of the West Indies Seismic Research Centre (UWI-SRC), University of the West Indies, St. Augustine, Trinidad & Tobago, West Indies (URL: http://www.uwiseismic.com/); National Emergency Management Organisation (NEMO), Government of Saint Vincent and the Grenadines, Bise, PO. The lava dome continued to grow to the N and S during April, accompanied by small earthquakes and gas-and-steam emissions rising both from the top of the dome and along the contact with the pre-existing 1979 dome. Calderas of gravity-slide structures in the Lesser Antilles Island Arc?. The eruptionthe volcano's first explosive event since 1979prompted thousands of people to evacuate. Bull Cent Geol Surv, 3: 31-43. That visit found nothing out of the ordinary. Analysis of infrared imagery from NOAA's SMS-1 weather satellite indicates that most of these high eruption clouds were fed briefly (less than 1/2 hour) by the volcano. Simon Carn noted that this makes the La Soufriere eruption the largest tropical SO2 emission since the 2011 Nabro eruption, and the largest in the Caribbean since satellite measurements began in 1979. Eruptions at La Soufrire volcano have propelled ash and gas high into the air over the Caribbean islands of Saint Vincent and Barbados. Ashfall was observed in most areas of the St. Vincent Island, as well as on neighboring islands of the Grenadines (SSW), Barbados (165 km E), and Saint Lucia (50 km NNE). Magmagenesis at Soufriere volcano, St Vincent, Lesser Antilles Arc. Restrictions remain in effect for the 4,000 persons who live in the zone devastated by the 1902 eruption, N of the Rabacca and Wallibou Rivers. The explosions at La Soufriere were recorded by infrasound (low frequency) on Guadelope, almost 200 miles (300 kilometers) away. Card 1388 (02 May 1972) Crater situation unchanged in over a month. Scientists visited the dome on 16 January and collected rock samples from the W part of the dome. Most of the more than 17,000 evacuees were allowed to return to their homes on 14 May, including residents of the two largest towns near the volcano, Georgetown and Chateaubelair. Beginning around midday the periods between episodes of high-amplitude tremor lengthened from 1.5-4 hours to 5-8 hours. Harmonic tremor continued to saturate the instruments from 2200 on 12 April through 1600 on 14 April. Soufrire St. Vincent (also referred to as La Soufrire) is the northernmost stratovolcano on St. Vincent Island in the southern part of the Lesser Antilles. Overnight during 10-11 April ash again fell island-wide, and also in the Grenadines (to the SSW), Barbados, and Saint Lucia (50 km NNE). There are four seismometers on St. Vincent now; one on the rim of the crater, two on the crater flank, one in Kingstown. All Rights Reserved. Table 5. The largest event was registered as a Mw 3.5 at 0920 and was felt by local residents. One tremor episode on 16 April at 0615 that lasted about three minutes was accompanied by an explosion, followed by more than two hours of low-level tremor. . This writer concludes that the explosiveness of Soufrire magmas is a function of gas, not silica content, there being no direct relationship between these two components. . The NE rim of the 1.6-km wide summit crater is cut by a crater formed in 1812. An episode of tremor began at 2100 and lasted 40 minutes, and was possibly associated with a minor increase in venting. 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