LAST UPDATE: 3 July 2009
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BEZYMIANNY - (55o58' 42"N 160o35' 12"E), 2,882 m, KAMCHATKA (Russia)
As of the 3rd of July, the Kamchatkan Volcanic Eruption Response Team (KVERT) has reported that growth of the lava dome continues. Sudden ash emission related to this activity could affect low-flying aircraft in the vicinity of the volcano. Seismic activity of the volcano was at background levels. According to satellite data, volcano was obscured by clouds during all week.
Prior to its noted 1955-56 eruption, Bezymianny volcano had been considered extinct. The modern Bezymianny volcano, much smaller in size than its massive neighbors Kamen and Kliuchevskoi, was formed about 4700 years ago over a late-Pleistocene lava-dome complex and an ancestral volcano that was built between about 11,000-7000 years ago. Three periods of intensified activity have occurred during the past 3000 years. The latest period, which was preceded by a 1000-year quiescence, began with the dramatic 1955-56 eruption. This eruption, similar to that of Mt. St. Helens in 1980, produced a large horseshoe-shaped crater that was formed by collapse of the summit and an associated lateral blast. Subsequent episodic but ongoing lava-dome growth, accompanied by intermittent explosive activity and pyroclastic flows, has largely filled the 1956 crater.
The colour code at Bezymianny is currently at YELLOW.
MAUNA LOA - (19o28' 30"N 151o36' 30"W), 4,170 m, HAWAII
As of the 17th of June, the Hawaiian Volcano Observatory (HVO) has reported that Mauna Loa is not erupting. Slow extension, as measured by GPS receivers on opposite sides of the volcano, continued. Line lengths have been increasing at a slightly faster rate since September, 2008, due mostly to slippage on basalt faults beneath Mauna Loa's east flank and not to an increase in magma supply to the volcano. Recent instrumental problems with a summit GPS receiver have produced more-than-usual data scatter - this problem will be corrected when weather permits.
Tiltmeters have recorded no significant changes other than abrupt offsets that are related to instrumental issues or significant earthquakes. Diurnal tilt, or the tilting due to daily heating and cooling of the ground, was diminished by snowfall starting Christmas Eve, 2008. Sensors within a crack in Moku`aweoweo crater floor continued to record background gas concentrations and fumarole temperatures.
Since the beginning of January, 2005, HVO analysts have rarely located more than 10 earthquakes per week beneath Mauna Loa summit. Each week, 1-5 earthquakes are also located beneath the Kealakekua area of west Mauna Loa. These levels are typical of the past several years. The Kao`iki seismic zone between Mauna Loa and Kilauea volcano summits remained active with an average of about 10-40 earthquakes per week; these numbers may reflect increased seismic activity nearer Kilauea summit rather than increased Ka`oiki activity.
Massive Mauna Loa shield volcano rises almost 9 km above the sea floor to form the world's largest active volcano. Flank eruptions are predominately from the lengthy NE and SW rift zones, and the summit is cut by the Mokuaweoweo caldera, which sits within an older and larger 6 x 8 km caldera. Two of the youngest large debris avalanches documented in Hawaii traveled nearly 100 km from Mauna Loa; the second of the Alika avalanches was emplaced about 105,000 years ago (Moore et al. 1989). Almost 90% of the surface of the basaltic shield volcano is covered by lavas less than 4000 years old (Lockwood and Lipman, 1987). During a 750-year eruptive period beginning about 1500 years ago, a series of voluminous overflows from a summit lava lake covered about one fourth of the volcano's surface. The ensuing 750-year period, from shortly after the formation of Mokuaweoweo caldera until the present, saw an additional quarter of the volcano covered with lava flows predominately from summit and NW rift zone vents.
The colour code at Mauna Loa is currently at YELLOW.
SANGEANG SPI - (08o12' 00"S 119o04' 00"E), 1,949 m, INDONESIA
As of the 11th of June, the Volcanological Society of Indonesia (VSI) has reported that on 4 June the Alert Level for Sangeang Api was raised to 2 (on a scale of 1-4) due to recent increases in the number of earthquakes. White plumes rose 5-25 m during 1 May-3 June.
Sangeang Api volcano, one of the most active in the Lesser Sunda Islands, forms a small 13-km-wide island off the NE coast of Sumbawa Island. Two large trachybasaltic-to-tranchyandesitic volcanic cones, 1949-m-high Doro Api and 1795-m-high Doro Mantoi, were constructed in the centre and on the eastern rim, respectively, of an older, largely obscured caldera. Flank vents occur on the south side of Doro Mantoi and near the northern coast. Intermittent historical eruptions have been recorded since 1512, most of them during in the 20th century.
The colour code at Sangeang Api is currently at ALERT LEVEL 2.
YELLOWSTONE CALDERA - (44o26'00"N 110o40'00"W), 2,805 m, UNITED STATES (Wyoming)
SPECIAL LINK REGARDING THE "SUPERVOLCANO" DOCUDRAMA ON YELLOWSTONE
As of the 3rd of July, the Yellowstone Volcano Observatory (YVO), reported that during the month of June 2009, 77 earthquakes were located in the Yellowstone region. The largest event was a magnitude 3.3 on June 30 at 0952 hrs MDT, located about 15 miles east northeast of West Yellowstone, MT. This event was part of an ongoing small earthquake swarm that includes 25 events on June 30, beginning with the M3.3 The magnitudes during the swarm ranged from 3.0 to -0.2. Earthquake activity in the Yellowstone region is at relatively normal background levels.
Ground Deformation Summary: Through June 2009, continuous GPS data show that uplift of the Yellowstone Caldera has slowed but may be continuing. The WLWY station, located in the northeastern part of the caldera, has undergone a total of ~23 cm of uplift since mid-2004. Its record can be found at: http://pboweb.unavco.org/shared/scripts/stations/?checkkey=WLWY&sec=timeseries_plots×eries=raw
The currently observed reduction in uplift rate may be related to seasonal changes related to snowmelt and groundwater recharge. In several of the past 5 years, such changes have caused decreased uplift or slight subsidence, but were followed later in the year by continued uplift. The general uplift of the Yellowstone caldera is of scientific importance and will continue to be monitored closely by YVO staff.
The colour code at Yellowstone is currently at GREEN.
