Pallister J.S.,U.S. Geological Survey |
Major J.J.,U.S. Geological Survey |
Pierson T.C.,U.S. Geological Survey |
Hoblitt R.P.,U.S. Geological Survey |
And 11 more authors.
Eos | Year: 2010
High-silica rhyolite magma fuels Earth's largest and most explosive eruptions. Recurrence intervals for such highly explosive eruptions are in the 100- to 100,000year time range, and there have been few direct observations of such eruptions and their immediate impacts. Consequently, there was keen interest within the volcanology community when the first large eruption of high-silica rhyolite since that of Alaska's Novarupta volcano in 1912 began on 1 May 2008 at Chaitn volcano, southern Chile, a 3-kilometerdiameter caldera volcano with a prehistoric record of rhyolite eruptions [Naranjo and Stern, 2004; Servicio Nacional de Geologa y Minera (SERNAGEOMIN), 2008; Carn et al., 2009; Castro and Dingwell, 2009; Lara, 2009; Muoz et al., 2009]. Vigorous explosions occurred through 8 May 2008, after which explosive activity waned and a new lava dome was extruded.
Fontijn K.,University of Oxford |
Fontijn K.,Ghent University |
Rawson H.,University of Oxford |
Van Daele M.,Ghent University |
And 10 more authors.
Quaternary Science Reviews | Year: 2016
Well-characterised tephra horizons deposited in various sedimentary environments provide a means of synchronising sedimentary archives. The use of tephra as a chronological tool is however still widely underutilised in southern Chile and Argentina. In this study we develop a postglacial tephrochronological model for the Chilean Lake District (ca. 38 to 42°S) by integrating terrestrial and lacustrine records. Tephra deposits preserved in lake sediments record discrete events even if they do not correspond to primary fallout. By combining terrestrial with lacustrine records we obtain the most complete tephrostratigraphic record for the area to date. We present glass geochemical and chronological data for key marker horizons that may be used to synchronise sedimentary archives used for palaeoenvironmental, palaeoclimatological and palaeoseismological purposes. Most volcanoes in the studied segment of the Southern Volcanic Zone, between Llaima and Calbuco, have produced at least one regional marker deposit resulting from a large explosive eruption (magnitude ≥ 4), some of which now have a significantly improved age estimate (e.g., the 10.5 ka Llaima Pumice eruption from Llaima volcano). Others, including several units from Puyehue-Cordón Caulle, are newly described here. We also find tephra related to the Cha1 eruption from Chaitén volcano in lake sediments up to 400 km north from source. Several clear marker horizons are now identified that should help refine age model reconstructions for various sedimentary archives. Our chronological model suggests three distinct phases of eruptive activity impacting the area, with an early-to-mid-Holocene period of relative quiescence. Extending our tephrochronological framework further south into Patagonia will allow a more detailed evaluation of the controls on the occurrence and magnitude of explosive eruptions throughout the postglacial. © 2016 Elsevier Ltd.
Stebel K.,Norwegian Institute For Air Research |
Amigo A.,SERNAGEOMIN |
Thomas H.,Nicarnica Aviation AS |
Prata A.J.,Nicarnica Aviation AS
Journal of Volcanology and Geothermal Research | Year: 2015
Putana is a stratovolcano in the central Andes volcanic zone in northern Chile on the border with Bolivia. Fumarolic activiy has been visible at its summit crater at 5890m altitude from long distances since the early 1800s. However, due to its remote location neither detailed geological studies have been made nor gas fluxes have been monitored and therefore its evolution remains unknown. On November 28, 2012 an ultraviolet (UV) imaging camera was transported to Putana and for about 30min images of the fumaroles were recorded at 12Hz. These observations provide the first measurements of SO2 fluxes from the fumarolic field of Putana and demonstrate the applicability of the UV camera to detect such emissions. The measurement series was used to assess whether the sampling rate of the data influences the estimate of the gas flux. The results suggest that measurements made at 10s and 1min intervals capture the inherent (turbulent) variability in both the plume/wind speed and SO2 flux. Relatively high SO2 fluxes varying between 0.3kgs-1 and 1.4kgs-1, which translates to 26t/day and 121t/day assuming constant degassing throughout the day, were observed on November 28, 2012. Furthermore, we demonstrate how an optical flow algorithm can be integrated with the SO2 retrieval to calculate SO2 fluxes at pixel level. Average values of 0.64kgs-1±0.20kgs-1 and 0.70kgs-1±0.53kgs-1 were retrieved from a "classical" transect method and the "advanced" optical flow based retrieval, respectively. Assuming constant emissions throughout all times, these values would results in an average annual SO2 burden of 20-22 kT. © 2015.
News Article | November 21, 2016
Perú Sabancaya has been restless for the last two years, with periods of heightened activity and a return to quiet. However, it looks like the Peruvian volcano has entered a new phase of activity since early November. The volcano has produced dozens of explosive eruptions since November 6, when the renewed activity began. This first explosion generated an M3.6 earthquake as well. Ash has reached 1.5-3.5 kilometers (4,900-11,400 feet) over the volcano and spread ash over 40 kilometers (25 miles) from the volcano on the people living across the area. The ash plumes (see below) have been some of the highest ever recorded at Sabancaya and video from the explosions show a vigorous plume of dark grey ash from the volcano. Interestingly, the number of earthquakes is down some from late September and early October, possibly betraying the time for the magma to rise from depth into the volcano to cause these explosions. Deformation of the volcano continues, which supports the idea that magma is still rising into the edifice and sulfur dioxide emissions remain high (almost 3,000 tonnes/day), so all signs still point to continued likelihood of explosive eruptions. This continued threat means that a state of emergency has been declared across 23 districts around Sabancaya due to this ash hazard for the next 60 days. This area is a tourist destination, so any prolonged unrest at Sabancaya could impact that industry. The volcano remains on Yellow alert status. You can see the changing activity at Sabancaya on the webcam pointed at the crater. Sabancaya isn’t the only restless volcano in Peru right now, either. Ticsani has been experiencing earthquakes over the past few months that all suggest magma is moving into the volcano. The number of earthquakes has dropped some at Ticsani since earlier in the year, but harmonic tremor, a sure sign of magma movement, has increased over the past few weeks. However, deformation and degassing is low, so an eruption isn’t likely happening in the immediate future. The only known eruption of Ticsani was in ~1800 A.D. Ubinás has also had an eventful 2016, with numerous explosions from Peru’s most active volcano. Over the past few months, the volcano has had a couple bouts of seismicity that quieted during much of October. However, since the start of November, there have been numerous earthquakes, tremor and some explosions that sent ash ~1.5 km (4,900 feet) over the volcano. Those explosions coincided with a spike in sulfur dioxide emissions, all supporting the conclusions that new magma is rising into the volcano. You can check out the IGP webcam or INGEMMET webcam to see what’s going on at the restless Andean volcano. Further south, an explosive eruption on November 17 occurred at Nevados de Chillán that sent ash 1.2 kilometers (3,900 feet) over the volcano. This is one of a number of “ash puffs” that the volcano has produced over the last year, most of which were noticed thanks to the webcam pointed at the volcano. Nevados de Chillán remains at Yellow alert status. Meanwhile, M3.6 earthquake shook Hudson in southern Chile. The SERNAGEOMIN thinks the earthquake was related to fluid movement within the volcano, although it could be from hydrothermal activity rather than magma. The last eruption from Hudson was in 2011 and the 1991 eruption was a VEI 5, one of the largest of the 20th century.
News Article | December 2, 2016
Last night, the ONEMI (Oficina Nacional de Emergencias) and SERNGEOMIN (Chilean Geological Survey) in Chile raised the alert status for the area around Cerro Hudson in the southern Andes. Normally, raising the alert status like this is due to an acute change, when the behavior of the volcano shifts suddenly. However, this time, the elevation to Yellow alert status at Cerro Hudson is due to accumulated events over the past month. Dozens of small earthquakes have occurred since the start of November, none stronger than M3.2. But their location (in geographic space and depth) are similar to those before the last eruption of Hudson in 2011. The number of earthquakes hasn’t increased much above the baseline activity at an active volcano like Hudson, but energy released by the largest earthquakes has been increasing over the past few months. Combine that with the fact that the earthquakes have the character of those associated with magma movement, and the SERNAGEOMIN and ONEMI decided to treat Hudson with an abundance of caution, setting up a 3.5 kilometer exclusion zone around the volcano. Hudson is a fairly unknown volcano to most people, but it did produce one of the largest eruptions in the latter half of the 20th century. The 1991 eruption was a VEI 5 event, which is on the same scale as Mount St. Helens in 1980 (and a bit smaller than the much more famous eruption of Pinatubo that had happened earlier that year). Even the 2011 eruption, which was VEI 2, opened three new vents on the volcano and covered the ice-filled summit caldera with dark grey ash. So, any unrest like this at Hudson bears close watching. Mexico’s Popocatépetl had some of its strongest explosions of the year—large enough to force the closure of airports around Mexico City. The explosive plumes reached ~5 kilometers (~15,000 feet) and spread ash on the region. It was the removal of the ash from the runways that caused the Puebla Airport to close. You can watch all the rumblings and explosions at Popocatépetl on the webcam pointed at the volcano.