Volcanic Activity Appears To Be Working It's Way Around The "Ring of Fire"

Geologic Summary. Popocatépetl, whose name is the Aztec word for smoking mountain, towers to 5,426 m 70 km SE of Mexico City and is North America’s second-highest volcano. Frequent historical eruptions have been recorded since the beginning of the Spanish colonial era. A small eruption on 21 December 1994 ended five decades of quiescence. Since 1996 small lava domes have incrementally been constructed within the summit crater and destroyed by explosive eruptions. Intermittent small-to-moderate gas-and-ash eruptions have continued, occasionally producing ashfall in neighboring towns and villages.

January 9 - 15, 2008

TUNGURAHUA Ecuador 1.467°S, 78.442°W; summit elev. 5023 m

IG released a special report on 9 January noting that increased seismic activity at Tungurahua was comparable to that of the few days prior to the eruption of 14 July, 2006.

IG reported that although visual observations were occasionally limited due to cloud cover, ash-and-steam and ash plumes were observed and rose to altitudes of 6-9 km (19,700-29,500 ft) a.s.l. during 9-15 January. Ashfall was reported almost daily in areas to the NE, N, NW, W, and SW. Roaring noises and “cannon shots” were heard daily and windows and floors vibrated on 9, 10, 12, and 15 January, as far away as the Tungurahua Observatory (OVT) in Guadalupe, about 13 km NW. Incandescence at the summit was observed and incandescent blocks rolled 0.5-1 km down the flanks. On 11 January, Strombolian activity at the summit crater was observed and blocks rolled 600 m down the flank.

According to news articles, residents from two provinces continued to evacuate at night and about 20,000 health masks were distributed to residents from Baños and Quero.

Geologic Summary. The steep-sided Tungurahua stratovolcano towers more than 3 km above its northern base. It sits ~140 km S of Quito, Ecuador’s capital city, and is one of Ecuador’s most active volcanoes. Historical eruptions have all originated from the summit crater. They have been accompanied by strong explosions and sometimes by pyroclastic flows and lava flows that reached populated areas at the volcano’s base. The last major eruption took place from 1916 to 1918, although minor activity continued until 1925. The latest eruption began in October 1999 and prompted temporary evacuation of the town of Baños on the N side of the volcano.

January 11, 2008

FUEGO Guatemala 14.473°N, 90.880°W; summit elev. 3763 m

INSIVUMEH reported on 11 January that weak explosions from Fuego produced ash plumes that rose to altitudes of 4.1-4.3 km (13,500-14,100 ft) a.s.l. CONRED reiterated that the Alert Level remained at Yellow.

Geologic Summary. Volcán Fuego, one of Central America’s most active volcanoes, is one of three large stratovolcanoes overlooking Guatemala’s former capital, Antigua. The scarp of an older edifice, Meseta, lies between 3,763-m-high Fuego and its twin volcano to the N, Acatenango. Construction of Meseta volcano continued until the late Pleistocene or early Holocene, after which growth of the modern Fuego volcano continued the southward migration of volcanism that began at Acatenango. Frequent vigorous historical eruptions have been recorded at Fuego since the onset of the Spanish era in 1524, and have produced major ashfalls, along with occasional pyroclastic flows and lava flows. The last major explosive eruption from Fuego took place in 1974, producing spectacular pyroclastic flows visible from Antigua.

January 9 - 15, 2008

ST. HELENS United States 46.20°N, 122.18°W; summit elev. 2549 m

Data from deformation-monitoring instruments indicated that during 9-15 January lava-dome growth at Mount St. Helens continued. Seismicity persisted at low levels, punctuated by M 1.5-2.5, and occasionally larger, earthquakes. Clouds occasionally inhibited visual observations.

Geologic Summary. Prior to 1980, Mount St. Helens formed a conical, youthful volcano sometimes known as the Fuji-san of America. During the 1980 eruption the upper 400 m of the summit was removed by slope failure, leaving a 2 x 3.5 km horseshoe-shaped crater now partially filled by a lava dome. Mount St. Helens was formed during nine eruptive periods beginning about 40-50,000 years ago, and has been the most active volcano in the Cascade Range during the Holocene. The modern edifice was constructed during the last 2,200 years, when the volcano produced basaltic as well as andesitic and dacitic products from summit and flank vents. Historical eruptions in the 19th century originated from the Goat Rocks area on the N flank, and were witnessed by early settlers. LINK

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