General Volcanic Activity Thread!

[john pike]

Volcanoes Today, 8 Jul 2014: Vulcano, Stromboli, Etna, Kilauea

Tuesday Jul 08, 2014 08:00 AM |

View onto the Sciara del Fuoco (INGV webcam)

The new lava flows from the eastern base of Etna's NE crater on 6 July (photo: Emanuela / VolcanoDiscovery Italia)

This comparison of the normal photograph with a thermal image shows the extent of the lava shield clearly. The lava shield is visible as the area of high temperatures (hot colors) in the thermal image. Corresponding spots are marked with small arrows for reference.

Stromboli (Eolian Islands, Italy): Similar as during the last times, activity is fluctuating. After a few hours of increased lava effusions, it dropped and the new lava overflow creased again yesterday evening.

Etna (Sicily, Italy): no significant changes: lava continues to effuse from the new fissure vent at the eastern base of the NE crater. A small hornito has grown at the vent. Tremor continues to climb slowly. Emanuela visited the active lava flows yesterday:

Vulcano (Eolian Islands): Some impressions from La Fossa crater during our recent visit to Vulcano Island.

Kilauea (Hawai'i): Elevated eruption activity continues on the East Rift Zone of Kilauea - a low shield, topped by a perched lava pond, is growing over the active breakout point of the June 27 breakout, on the northeast flank of PuÊ»u ʻŌʻÅ. Overflows from the lava pond are spreading mostly toward the north and northeast, but are too short-lived to advance much beyond the shield's base. Sulfur-dioxide emission-rates have been elevated since this June 27th flow.

At this summit of Kilauea, the eruption within Halemaumau crater continues and the summit lava lake has stabilized at ~34m (110ft). This large lava lake, now 160m (520ft) by 210m (690ft) wide, continues to produce intense glow at both sunset and sunrise in turn making for some excellent photo opportunities!

Seismic tremor levels have been low however, with an average of 15 to 20 earthquakes per week.

[john pike]

Russia's active volcano Shiveluch, located on the Kamchatka peninsula in the country's Far East, spewed a series of ash emissions to a height ranging between five and 11 kilometers (3-7 miles), but the eruptions pose no threat to nearby residential areas, local volcanic research group reported on Tuesday. However, the Kamchatka Volcanic Response Team (KVERT) warned air traffic control services of the danger, which volcano poses to aircraft issuing the "Orange" code of warning for the aviation. The service advised airlines to alter their scheduled flight routes saying ash particles are capable of choking aircraft's engines. The Aviation Color Codes reflect four levels of danger posed for civilian aircraft overflying areas adjacent to volcanoes and range from 'Green' to 'Red' codes. According to the International Airways Volcano Watch system (IAVW) the 'Orange' code stands for "Volcano is exhibiting heightened unrest with increased likelihood of eruption" or "Volcanic eruption is underway with no or minor ash emission." The cloud of ash, which the 3,283-meter (10,771 feet) Shiveluch churned out as a result of three emissions over the past 24 hours, has extended to the length of 100 kilometers (62) miles and moves in the southeastern direction towards the Pacific Ocean. Local Emergencies Ministry's department warned tourism companies operating in the region against holding tours in areas located near the volcano. There are over 150 volcanos on the Kamchatka peninsula in Russia's Far East, and up to 30 of them are active.

 

http://hisz.rsoe.hu/alertmap/site/?pageid=event_desc&edis_id=VA-20140708-44460-RUS

[john pike]

Minor outburst floods are occurring in Múlakvísl and Jökulsá á Sólheimasandi in connection with geothermal activity beneath the Mýrdalsjökull ice-cap. The flood in Múlakvísl began around 2 July, resulting in higher-than-normal discharge and increased electrical conductivity. Conductivity readings have also increased at Jökulsá á Sólheimasandi, the river draining from Sólheimajökull, where floodwater presently drains from the ice margin.

Hydrogen sulphide is degassing from both rivers. At high concentrations, this gas, notable by its sulphur smell, can be highly toxic.Written by a specialist at 08 Jul 21:31 GMT

 

http://en.vedur.is/#tab=vatnafar

[john pike]

Global cooling caused by some historic volcanic eruptions wasn't as extreme as climate scientists recently thought, according to newly revised ice core records from Antarctica.

Volcanic eruptions blast sulfur-dioxide gas into the stratosphere, where it turns into tiny particles called sulfate aerosols that reflect the sun's energy and cool the Earth. Snow falling in Antarctica records the levels of sulfate in the air at the time, and it eventually becomes ice drilled by researchers in long, tubular cores.

Researchers have measured sulfate concentrations in 26 ice cores from 19 different locations in Antarctica that cover the last 2,000 years of Earth's history — the best record yet, the researchers said. The team synchronized the sulfate records with ice cores from Greenland, to determine if the eruptions had a truly global effect.

 

http://www.livescience.com/46696-volcanoes-cooling-antarctic-ice-cores.html

 

more in link above

[john pike]

Katla volcano update: increased earthquake activity, uncertainty level declared

Wednesday Jul 09, 2014 09:37 AM | BY: T

Epicenters of earthquakes at Katla during the past 7 days

Depth & magnitude vs time of earthquakes under Katla

Earthquakes have been more frequent recently under the volcano recently. Most of them were small (below mag. 3) and shallow events. It is unknown whether these relate to magmatic movements inside the volcano, increased hydrothermal activity or are adjustments of the ice cap due to increased melting.

The government has declared "Uncertainty level" for Katla volcano yesterday. The largest hazard comes in the form of melt-water floods and sulfurous volcanic gasses dissolved in and released from glacial rivers.

People are advised not to stop at Múlakvísl and Jökulsá and other glacier river valleys and keep cell phones turned on in order to be able to receive potential SMS alerts.

Currently, there are no signs of an impending eruption at Katla.

[*]All news about: Katla volcano

[*]Information about: Katla volcano

[karyo]

Katla volcano update: increased earthquake activity, uncertainty level declared

Wednesday Jul 09, 2014 09:37 AM | BY: T

Epicenters of earthquakes at Katla during the past 7 days

Depth & magnitude vs time of earthquakes under Katla

Earthquakes have been more frequent recently under the volcano recently. Most of them were small (below mag. 3) and shallow events. It is unknown whether these relate to magmatic movements inside the volcano, increased hydrothermal activity or are adjustments of the ice cap due to increased melting.

The government has declared "Uncertainty level" for Katla volcano yesterday. The largest hazard comes in the form of melt-water floods and sulfurous volcanic gasses dissolved in and released from glacial rivers.

People are advised not to stop at Múlakvísl and Jökulsá and other glacier river valleys and keep cell phones turned on in order to be able to receive potential SMS alerts.

Currently, there are no signs of an impending eruption at Katla.

• All news about: Katla volcano
• Information about: Katla volcano

 

I am starting to feel a little excited! 

 

Karyo

[john pike]

There are indications that a small glacial outburst flood is occurring in the river Múlakvísl, which originates in Mýrdalsjökull glacier, where the volcano Katla is located.

The Civic Protection Department of the National Commissioner of the Icelandic Police declared yesterday a level of uncertainty because of the flood, which is believed to have started on July 2.

Employees of the Icelandic Met Office have placed sensors on the new bridge that is being built across Múlakvísl to measure the water flow and conductivity in the river. The uncertainty level does not affect the bridge’s construction, ruv.is reports.

There are a number of calderas near Katla, created by geothermal heat, but it is uncertain where the flood originates. Hydrogen sulfide is being carried into Múlakvísl and travelers are asked not to stop by the river because of dangerous gases, mbl.is reports.

Conductivity has also increased in the river Jökulsá, which originates in the Mýrdalsjökull glacial tongue Sólheimajökull, a popular tourist destination.

“It isn’t unusual that a leak or minor flood of this kind comes from Mýrdalsjökull in the summer and it’s possible that the flow of water will increase,†a statement from the Met Office reads.

“Data doesn’t indicate any bigger events following the flood but it is possible that a larger flood could happen suddenly with little notice.â€

A small glacial outburst flood occurred in Múlakvísl last year as well but exactly three years ago to the date a major flood occurred in the river, destroying the old bridge and tearing a hole in the Ring Road which interrupted the tourist season.

 

http://icelandreview.com/news/2014/07/09/small-glacial-outburst-flood-south-iceland

 

http://ruv.is/frett/verdur-sennilega-litid-hlaup

 

click on link above for v short video

Edited July 9, 2014 by john pike

[john pike]

http://en.vedur.is/about-imo/news/nr/2917

 

more re katla at present

 

also just had another 2.2 quake

 

http://en.vedur.is/earthquakes-and-volcanism/earthquakes/myrdalsjokull/#view=table

 

cannot call this.

 

all we can do is watch to see what happens next

[john pike]

Volcanoes Today, 10 Jul 2014: Stromboli, Veniaminof, Sinabung, Zhupanovsky, Kilauea

Thursday Jul 10, 2014 09:00 AM |

Lava flow on Stromboli this morning

SO2 plume from Zhupanovsky volcano this morning (ESA)

Small pyroclastic flow at Sinabung this morning

This before and after comparison from the USGS webcam east of Puʻu ʻŌʻŠshows the dramatic change to the skyline that this new lava shield has created.

Stromboli (Eolian Islands, Italy): Two new lava (over-)flows occurred from the NE vent last evening and this morning. Similar as during the previous episodes, the flows were the result of surges in magma supply, quickly descended the upper part of the Sciara del Fuoco, and then stopped:

It almost appears that these peaks of activity are following each other at intervals of 2-3 days.

 

 

Zhupanovsky (Kamchatka, Russia): Eruptions continue or have resumed at the volcano. Ash and SO2 plumes rising to approx. 6 km altitude and drifting east have been detected on satellite data this morning.

Sinabung (Sumatra, Indonesia): A small pyroclastic flow occurred on the slope of the volcano this morning. The flow was confined to the slope of the summit cone and did not reach the devastated areas at the SE base.

Similarly as during other such events in the past weeks, it originated from a moderate collapse on the upper part of the still active viscous lava lobe.

Kilauea (Hawai'i): The June 27 breakout has remained active over the past week, emitting short lava flows from the vent on PuÊ»u ʻŌʻÅ's northeast flank. These flows have stacked upon one another creating a lava shield, which now hosts a lava pond.

Veniaminof (Alaska Peninsula, USA): Signs of volcanic activity have been absent for a while and the Due to the recent decrease in seismic activity and absence of detectable volcanic activity, the Alaska Volcano Observatory (AVO) lowered the alert level back to normal:

"Seismic activity, indicative of unrest, at Veniaminof has decreased to near background levels during the past week. Clear eruptive activity has not been observed since October of 2013. Thus AVO is lowering the Aviation Color Code to Green and the Volcano Alert Level to Normal. Occasional steam plumes and weakly elevated surface temperatures may continue to be seen in satellite and webcam imagery as lava flows cool.

It is possible that this is only a temporary pause of activity in the eruption that began in June 2013, and that the eruption could resume. Pauses in eruptive activity are not uncommon at this volcano. AVO will continue to monitor the volcano closely." (AVO)

[karyo]

http://en.vedur.is/about-imo/news/nr/2917

 

more re katla at present

 

also just had another 2.2 quake

 

http://en.vedur.is/earthquakes-and-volcanism/earthquakes/myrdalsjokull/#view=table

 

cannot call this.

 

all we can do is watch to see what happens next

The latest quake is very shallow so probably due to the ice melting and re-positioning. 

 

Karyo

[john pike]

hi karyo

 

at 1.2 km deep i would call that magma movement related.

 

still facinating to see what happens next

 

[karyo]

I hope you are right but I feel we may be heading to an event similar to summer 2011 when there was a glacial flood and a collapsed bridge but no proper eruption.

 

Unless of course, the quakes increase and she goes bang!

 

Karyo

[Buriedundersnow]

certainly interesting to see katla hiccupping away hopefully it will really come to life soon but would prefer to see more quakes going on.

 

here's one for you roads melting in Yellowstone due to heat wave well is it really the heat its only been in the low 80's and surely that isn't enough to melt the road like that as it doesn't in other parts of the world plus why have hikers to stay away from the affected area a bit suspect in my eyes

 

http://www.accuweather.com/en/weather-news/yellowstone-heat-road-melts/30238184

[Buriedundersnow]

for anyone interested tonight on discovery science channel 219 on virgin don't know what it is on other networks at 8pm theres a program called timebomb Iceland about the eruption of 2010 and what could come next from Icelands volcanoes may be an interesting watch it is repeated after at 9pm on the +1 channel

Edited July 17, 2014 by Buriedundersnow

[Yarmy]

for anyone interested tonight on discovery science channel 219 on virgin don't know what it is on other networks at 8pm theres a program called timebomb Iceland about the eruption of 2010 and what could come next from Icelands volcanoes may be an interesting watch it is repeated after at 9pm on the +1 channel

 

Cheers. It's 525 on Sky, or 557 for the +1.

[john pike]

Volcanoes Today, 20 Jul 2014: Stromboli, Ubinas, Slamet

Sunday Jul 20, 2014 08:00 AM |

Lava flow on Stromboli 17 July evening

Explosion at Ubinas volcano 17 July (IGP)

Stromboli (Eolian Islands, Italy): Overall, activity remains similar. Several smaller and larger, but all short-lived lava overflows occurred from the second NE vent over the past days.

The most significant of these lava flows was in the evening of 17 July.

Time-lapse video 15-20 July:

 

Slamet (Central Java): Ash emissions were observed again today, producing plumes rising a few 100 m above the volcano's summit. The strombolian activity in the summit crater is continuing, at least intermittently.

Ubinas (Peru): A relatively powerful explosion occurred yesterday at 08:15 local time, producing an ash plume rising 5 km above the volcano's crater.

[john pike]

Recent Kilauea Status Reports, Updates, and Information Releases HAWAIIAN VOLCANO OBSERVATORY DAILY UPDATE Monday, July 21, 2014 7:31 AM HST (Monday, July 21, 2014 17:31 UTC)

This report on the status of Kilauea volcanic activity, in addition to maps, photos, and Webcam images (available at http://hvo.wr.usgs.gov/activity/kilaueastatus.php), was prepared by the USGS Hawaiian Volcano Observatory (HVO). All times are Hawai`i Standard Time.

KILAUEA VOLCANO (VNUM #332010)

19°25'16" N 155°17'13" W, Summit Elevation 4091 ft (1247 m)

Current Volcano Alert Level: WATCH

Current Aviation Color Code: ORANGE

Activity Summary: Kīlauea continued to erupt at its summit and within the East Rift Zone, and gas emissions remained elevated. There was no significant change in tilt recorded at the summit, and the lava lake level was relatively steady. At the middle East Rift Zone, lava flows continued to erupt from the northeast flank of Puʻu ʻŌʻŠcone, spreading to the northeast.

Recent Summit Observations: Summit tiltmeters recorded no significant change in tilt over the past 24 hours. The lava lake level fluctuated gently between about 30 and 35 m below the Overlook crater rim. Seismic tremor varied between hours-long periods of low tremor and tremor dropouts. Fifteen earthquakes were strong enough to be located beneath KÄ«lauea Volcano: 1 beneath the summit, 5 in the East Rift Zone, 5 on south flank faults, 1 northeast of the summit, and 3 in the KaÊ»Åiki Pali area. GPS receivers spanning the summit caldera recorded variations of up to about 1 cm since early July, but little overall change in length. During the week ending on 07/15/14, the elevated summit SO2 emission rate was 4,200-6,300 tonnes/day (see caveat below), and a tiny amount of particulate material was carried aloft by the plume.

Recent East Rift Zone Observations: Lava flows from the June 27th breakout continued to spread toward the northeast in two main lobes, reaching about 2 km from the vent on the northeast flank of PuÊ»u ʻŌʻÅ. Rainfall at PuÊ»u ʻŌʻŠover the past day prevents meaningful interpretation of the tilt signal recorded there. Small lava ponds were present within the two southeastern pits in the crater floor, and glow above the other two pits indicated lava was at least close to the surface there as well. The most recent sulfur-dioxide emission-rate measurement was 500 tonnes per day (from all East Rift Zone sources) on July 3, 2014; emission rates have typically ranged between 150 and 450 t/d since July 2012.

 

http://hvo.wr.usgs.gov/activity/kilaueastatus.php

 

 

 

Recent Mauna Loa Status Reports, Updates, and Information Releases HAWAIIAN VOLCANO OBSERVATORY MONTHLY UPDATE Monday, July 21, 2014 7:30 AM PDT (Monday, July 21, 2014 14:30 UTC)

MAUNA LOA VOLCANO (VNUM #332020)

19°28'30" N 155°36'29" W, Summit Elevation 13681 ft (4170 m)

Current Volcano Alert Level: NORMAL

Current Aviation Color Code: GREEN

No significant changes were recorded through May 2014.

Seismicity: Seismicity continued to be elevated over the average rates of the past 25 years-12 shallow events below summit area, 6 events to the west of MokuÊ»Äweoweo Crater (<13 km), 5 events to the north of MokuÊ»Äweoweo Crater, 16 shallow events on the Upper Southwest Rift (Sulfur Cone), 4 shallow events on the Lower Southwest Rift, 2 shallow events on the NE Rift Zone.

Deformation: GPS and tilt networks did not record any changes in deformation rates or patterns that were significantly above the error of the measurements during June. Southeasterly motion of the south flank continued.

Gas: No significant changes in SO2, CO2 were recorded by the Mokuaweoweo gas and temperature monitors in May. Daily average fumarole temperature during the month declined from 76 to 75 degrees C, still not back down though to the 71.7 degrees average of several months ago.

Background: Re-inflation of Mauna Loa's shallow magma storage reservoirs started immediately following the most recent eruption in 1984, then turned to deflation for almost a decade. In mid-2002, inflation started again, just after a brief swarm of deep long-period (LP) earthquakes. A more intense swarm of several thousand deep Long Period (LP) earthquakes occurred in late 2004, immediately preceding a dramatic increase in inflation rate. Inflation slowed again in 2006, ceased altogether in late 2009, and resumed slowly in late 2010.

Rising gradually to more than 4 km above sea level, Mauna Loa is the largest active volcano on our planet. Its long submarine flanks descend to the sea floor an additional 5 km, and the sea floor in turn is depressed by Mauna Loa's great mass another 8 km. This makes the volcano's summit about 17 km (56,000 ft) above its base! The enormous volcano covers half of the Island of Hawai`i and by itself amounts to about 85 percent of all the other Hawaiian Islands combined.

 

http://hvo.wr.usgs.gov/activity/maunaloastatus.php

 

plus alaska updates in link below

 

http://www.avo.alaska.edu/

[john pike]

Navigation.

A very large rockslide fell into lake Öskjuvatn, from the SE rim of Askja.

Rockslide into Askja caldera

23.7.2014

An very large rockslide fell into lake Öskjuvatn, from the southeastern rim of Askja, at 23:24 on Monday evening 21 July 2014.

Askja is a central volcano and a large caldera situated in a remote part of the central highlands of Iceland. It has a lake in its smaller caldera, which resulted from an 1875 eruption. It is the youngest of such formations on Earth.

As a consequence of the rockslide, a small tsunami traversed the lake and into Víti, a smaller explosion crater on the northeastern shore of Öskjuvatn. Tremors were detected for 20 minutes on seismometers in the area. A witness saw a plume rise from Askja, light in colour, but its origin or composition is not clear.

The weather has been warm. Temperatures have been rather high with more frequent rainfall than usually and a lot of snowmelt has taken place which might have triggered this event, catastrophic in proportions but without any damage or casualty because no tourists nor scientists were present. Parts of the caldera‘s rim might still be unstable and more material might fall into the lake.

The situation was reviewed this morning by scientists from IMO, the University of Iceland and the Civil Protection System of the Icelandic police. Scientists are now on the way to Askja to evaluate the impact of the rockslide and any remaining hazards. Traffic in the area is restricted until further notice. The responsible authority for the Askja region is the police in Húsavík.

A video is available from RÚV, The Icelandic National Broadcasting Service.

Askja rockslide

The southeast slope of Askja, where the slide originated. Photo: Kristján Einarsson.

Plume of unknown origin

Askja from a distance. A plume was seen 21 July 2014 at 23:27 but its origin and composition are unknown. Photo: Kolbeinn Helgi Gíslason.

[john pike]

Volcanic activity worldwide 23 Jul 2014: Semeru, Askja, Santiaguito, Fuego, Reventador, Ubinas, Aso,...

Wednesday Jul 23, 2014 15:57 PM |

Glow at Aso's Nakadake crater this morning

Glow from Semeru's summit at night (VSI webcam)

MODIS hot spots at Shishaldin (MODVOLC, Univ. Hawaii)

Current seismic activity (CEAP station / AVO)

Tremor amplitude at Chaparrastique volcano over the past weeks (MARN)

Small ash emission at Reventador yesterday

Gas plume from Ubinas with possibly some ash this morning

Zhupanovsky (Kamchatka, Russia): Several small ash emissions occurred at the volcano during 16-21 July. The resulting plumes dissipated quickly. Aviation color code is at orange.

Aso (Kyushu): Activity remains elevated at Asosan volcano. Although no new ash emissions were reported recently, the Nakadake crater shows intense degassing and bright glow from hot fumaroles is visible at night. It seems that the crater lake which usually occupied the bottom of the crater has evaporated.

Semeru (East Java, Indonesia): Activity, weak during the past months, seems to have picked up. A new lava flow has started to slowly descend the southeastern slope.

Since the intense explosive phase of activity in February 2012, accompanied by pyroclastic flows down the southern slope, a lava dome has been growing slowly inside the breached summit crater. This dome now started to form a more or less coherent lava lobe that began descending through the notch onto the upper southern slope. Weak glow is visible at night.

As a comparison of satellite images between 7 June and 16 July, compiled by Culture Volcan shows the progression of a tongue of hot material inside the ravine, likely a lava flow reaching 1,5-2 km length.

The presence of this flow has been causing almost constant rockfalls from the front of the flow into the Kembar ravine.

Shishaldin (United States, Aleutian Islands): According to the Alaska Volcano Observatory, weak activity continues. MODIS data show elevated surface temperatures in the summit crater, but there are no visual or other indicators of eruptive activity available.

Semisopochnoi (United States, Aleutian Islands): Earthquakes have decreased but are still above background levels. No eruptive activity has been recorded. Alert level remains yellow.

Santiaguito (Guatemala): No explosions were observed since yesterday, but the lava flow at the eastern rim of the Caliente dome remains active, producing rockfalls into the Nima 1 river canyon. Strong degassing is occurring from the dome.

Fuego (Guatemala): No significant changes in activity have occurred at the volcano. The observatory reported 8 weak and one moderate strombolian-type explosion since yesterday.

Ash plumes rose up to 800 m above the crater, and produced avalanches of glowing material on the upper slope. No lava flow was active.

San Miguel (El Salvador): The volcano continues to produce important gas emissions as well as occasional small ash explosions. Tremor remains at very high levels (20 times above normal), caused by internal fluid movements. The likelihood of new eruptive activity in the near to medium future remains elevated.

Cerro Negro de Mayasquer (Colombia): Seismic unrest continues at the volcanic massif of Chiles and Cerro Negro. However, it decreased during the past week with less than 700 events recorded, compared to 1500-1800 per week during the month before.

Most earthquakes were associated with internal rock fracturing and located at shallow 1-7 km depth in an area 4 km SW of the Chiles dome. Magnitudes reached 2.7 and some quakes were felt.

Slight deformation has been detected at the Chiles dome as well.

Reventador (Ecuador): Intermittent small explosions continue as well as slow lava extrusion at the summit, evidenced by thermal hot spots visible on satellite data.

Ubinas (Peru): The volcano has been relatively calm over the past days, producing mostly a very weak gas plume with dilute ash, as well as sporadic small explosions.

[john pike]

http://icelandreview.com/news/2014/07/23/askja-closed-due-huge-landslide

[john pike]

Navigation.

Askja 22 July 2014.

Seismic signal associated with the Askja rockslide Martin Hensch, Sigþrúðyour Ãrmannsdóttir and Kristín S. Vogfjörð

Veðurstofa Ãslands 24.7.2014

The huge rockslide on the eastern caldera rim of Askja volcano on 21st July 2014 around 23:25 was accompanied by a strong and unusual seismic signal, seen even far away from the source region.

The signal appeared on tremor graphs on all seismometers around Askja. It started with a strong pulse that subsequently decreased over the next 20-25 minutes (see figure 1, enlarge). Similar signals are sometimes seen for strong earthquakes far away from Iceland, however no strong earthquake had been detected by international networks at the same time.

Figure 1

 

Detailed investigation of the signal revealed that its frequency in the initial phase was around 0.05 Hz, which is unusually low. Figure 2 (enlarge) shows seismograms filtered between 0.02 and 0.2 Hz. The onset of the first wave is marked in red. The low frequency signal is followed by higher frequencies of about 1-4 Hz, which slowly fade out over the next twenty minutes. This signal can be seen on all seismometers around Askja, while the low frequency signal can be seen on broadband seismometers throughout the whole country.

The traveltime of the signal from Mókollar (mko) close to Askja to station Ãsbjarnarstaðir (asb) in Borgarfjörðyour is about 55 s; the distance between both stations is about 220 km. This gives the signal an apparent velocity of around 4 km/s, which is characteristic for a surface wave. As no body waves are seen prior to the low frequency onset, this event clearly differs from a normal tectonic earthquake which usually starts with clear onsets of P- and S-waves prior to the surface waves.

Figure 2

Interpretation

The preliminary interpretation of this signal is that the low frequency waves in the beginning reflect a slow rupture process in the slope of the caldera wall. The peak in tremor is subsequently caused by the debris fall into the lake. The following flood wave in the lake migrated several times back and forth, causing continuing but decreasing tremor that was seen during the next twenty minutes after the rockslide.

 

http://en.vedur.is/earthquakes-and-volcanism/articles/nr/2921

 

info thanks to iceland met office

 

link supplied

[john pike]

Askja Remains Closed as Scientists Research Rockfall

Specialists from the Icelandic Met Office and earth scientists from the University of Iceland were at Askja today to research the rockfall which occurred in the area on Monday night. The scientists are trying to determine the cause of the event and whether it is related to activity in the volcano.

 

http://icelandreview.com/news/2014/07/24/askja-remains-closed-scientists-research-rockfall

 

cannot wait for their results

[john pike]

Etna volcano update: Opening of a new vent at E base of North-East Crater

Saturday Jul 26, 2014 00:41 AM |

Thermal image of the effusive vents at the base of the NE crater with the lava flow (Monte Cagliato webcam, INGV Catania)

The New SE crater with a steam ring (Montagnola webcam, INGV Catania)

Ash emission from the New SE crater (Montagnola webcam, INGV Catania)

A new vent opened yesterday morning at 11:14 local time.

It is located about 150-200 metres north of the two previous vents at the eastern base of the NE crater.

Its activity is characterized by small strombolian explosions while a lava flow continues to be weakly alimented from one of the two other vents

In the meantime sporadic emissions of hot gas sometimes associated with ash emissions continue from the New SE crater .

[*]All news about: Etna volcano

[*]Information about: Etna volcano

[john pike]

Volcanic activity worldwide 28 Jul 2014: Ibu, Reventador, Kilauea, Nishino-shima, Karangetang, Dukon...

Monday Jul 28, 2014 17:19 PM |

Nishinoshima on 23 July (image: Japanese Coast Guard)

MODIS hot spots at Karangetang volcano last week (MODVOLC, Univ. Hawaii)

MODIS hot spots at Ibu volcano (MODVOLC, Univ. Hawaii)

Explosive eruption at Halema'uma'u lava lake on 23 July

Pyroclastic flow from an explosion at Reventador on 26 July evening (IGPEN webcam)

Summary of some of the most significant events during the past days:

Zhupanovsky (Kamchatka, Russia): Intermittent eruptions continue. New ash emissions occurred yesterday from the volcano. VAAC Tokyo spotted an ash plume at estimated 28,000 ft (8 km) altitude drifting north on satellite imagery.####

Nishino-shima (Volcano Islands): Activity at the growing island continues, perhaps even with increased intensity, judging from the recent pictures obtained by the Japanese Coast Guard on 23 July:
They show active lava flows reaching the sea and enlarging the island continuously, most notably towards the east, where a stretch of new land up to 250 m wide was added during only 1 month!

Much of this growth can be attributed to a new effusive vent located near the coast itself (s. second picture). However, it is unclear whether it is a true vent or only a so-called ephemeral vent formed by lava exiting a tube system and ultimately still coming from the central vent.
At the central vent, a prominent cone has grown by ongoing explosive activity, strombolian-type, ejecting lava bombs and ash plumes. The cone now probably surpasses the still official summit height of the island, 38 m, formed by the peak of the older, now small-in-comparison part that formed the island before the current eruption.

 

Karangetang (Siau Island, Sangihe Islands, Indonesia): An comparably small eruption occurred last week at the volcano. Incandescent lava avalanches were reported to descend from the summit lava dome to the SE, towards the area of Batu Awang, during 19-21 July.
It seems to have been a short-lived and relatively small event that did not form the feared pyroclastic flows (which Karangetang is notorious for): avalanches of gas-rich fresh lava that detaches from the dome and/or lava flows and turns into devastating hot turbulent flows that can reach many kilometers distance.

A thermal hot spot visible on MODIS data also suggested that fresh lava was present at the summit dome and on the flanks. The signal disappeared during the past days and no more news about volcanic activity were found.


Ibu (Halmahera, Indonesia): New thermal signals have been detected recently coming from the northern rim of the volcano's summit crater, suggesting that the volcano has entered a phase of increased activity.####
The rarely visited remote Ibu volcano has been in more or less continuous eruption since 1998, slowly growing a new lava dome as well as producing strombolian to vulcanian-type explosions, with significant variations in intensity. The new thermal signals, in the same area where glowing rockfalls had been reported last year, probably indicate that the (continued) lava extrusion has increased recently.

Dukono (Halmahera): Activity at the volcano continues to be elevated. VAAC Darwin frequently spots ash plumes from relatively strong strombolian to vulcanian activity.####

Kilauea (Hawai'i): A piece of the crater walls of the Halema'uma'u lava lake collapsed on 23 July and triggered a small explosive eruption. Liquid spatter was ejected to the outer perimeter of the pit crater (including webcam position and the closed observation area) and an ash plume was generated.####
The reason for the event was a sudden disturbance of the gas influx and release equilibrium of the lava lake induced by the rockfall, triggering a spontaneous and very strong degassing phase.

Reventador (Ecuador): Activity at the volcano has increased with more frequent small to moderately sized explosions from the growing lava dome in its summit. An explosion on the evening of 26 July generated a pyroclastic flow on the southwestern slope that reached almost 1 km length.###
Seismic activity reflects frequent explosions and tremor, but visual observations are often not possible due to frequent cloud cover. IGPEN characterizes the activity as "moderate". The volcano's activity at the present does not pose a risk for the closest inhabited areas approx. 8 km away. Edited July 28, 2014 by john pike

[john pike]

Tungurahua volcano (Ecuador): increase of activity, ash emission

Tuesday Jul 29, 2014 16:15 PM | BY: T

Ash emission of Tungurahua volcano last Sunday (photo: P. Espín OVT/IG-EPN)

Seismic signal Sunday evening (RETU station, IGPEN)

Deformation at RETU station showing the recent radial inflation (IGPEN)

Following more than 2 months of calm, the volcano is probably about to enter a new eruptive phase, a special bulletin of Ecuador's Geophysical Institute (IGPEN) informs.

Following a steep increase in seismic activity last Sunday afternoon, a small ash emission occurred at 15h49 local time, producing a plume rising approx. 1 km and causing light ash fall.

The black color of the ash suggests that it originated from a new batch of fresh magma that started to arrive in the summit crater.

Since Sunday evening, the volcano's seismic activity has continued to increase, in particular with regards to so-called long period earthquakes, believed to be signs of fluid movements (magma, gasses, water) inside the volcano. The observed seismicity is somewhat similar to the precursor activity that preceded the eruptions of Tungurahua in February and April this year. Surface activity could for most of the time not be observed due to bad weather.

In addition to the increase in seismic activity, significant inflation of the NE flank has occurred over the past weeks, another indication that magma started to rise within the volcano. The volcano observatory mentions that similar inflation patterns were observed shortly before the explosive eruptions on 18 October 2013, 1 February and 4 April this year.

Based on these monitoring observations and the typical behavior of the volcano during past eruptions, it is likely that the volcano is at the beginning of another, potentially violent eruptive phase. This could include persistent strombolian activity, and/or increasingly strong ash emissions as well as sudden and very violent vulcanian-type explosions with the potential of forming dangerous pyroclastic flows.

Significant ash falls could also occur in downwind locations. The most threatened areas include the stretches between Pelileo and Banos and Banos and Penipe.

[*]All news about: Tungurahua volcano

[*]Information about: Tungurahua volcano

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Links / Sources:

[*]INFORME ESPECIAL DEL VOLCÃN TUNGURAHUA N° 16 (IGPEN)

 

 

 

 

http://www.volcanodiscovery.com/tungurahua/news/46456/Tungurahua-volcano-Ecuador-increase-of-activity-ash-emission.html