Exclusion Zone Set Up Around Indonesia’s Anak Krakatau (Child of Krakatoa)

By MARK DUNPHY – Fri Oct 07, 2011

On July 31, 2011, a wispy ash plume rose above the volcano and drifted west (up in the below image). The natural-colour satellite image was acquired by the Advanced Land Imager (ALI) aboard Earth Observing-1 (EO-1). Dark gray areas of Anak Krakatau are composed principally of lava flows deposited in the 1970s, ’80s, and ’90s. These flows are topped by a young cinder cone near the center of the island. Green vegetation covers older lavas along the eastern coastline.  Image NASA. Instrument:  EO-1 – ALI

On July 31, 2011, a wispy ash plume rose above the volcano and drifted west (up in the below image). The natural-colour satellite image was acquired by the Advanced Land Imager (ALI) aboard Earth Observing-1 (EO-1). Dark gray areas of Anak Krakatau are composed principally of lava flows deposited in the 1970s, ’80s, and ’90s. These flows are topped by a young cinder cone near the center of the island. Green vegetation covers older lavas along the eastern coastline. Image NASA. Instrument: EO-1 – ALI

Anak Krakatau’s alert level has been raised to the second-highest level after the number of volcanic tremors soared from 200 a day to 7,200.  A 2-kilometre exclusion zone has also been established around the Indonesian volcano prohibiting tourists and fishermen from getting close to the volcanic island, located in the Sunda Strait between the islands of Java and Sumatra in Indonesia.

Indonesia’s Volcanology and Geology Disaster Mitigation Centre has expressed concern that an eruption could send incandescent rocks down its slopes and a considerable distance into surrounding waters.  The Center indicated, however, that a major eruption like that experienced in 1883 is unlikely.

Anak Krakatau, which is Indonesian for ‘Child of Krakatoa’, erupted briefly on Tuesday sending columns of ash and rock hurtling high into the air. The eruption was the biggest since January 2011 when ash was emitted more than 600 m into the air, forcing the evacuation of tens of thousands of residents. The volcano also erupted on 29th October 2010 leading Indonesian authorities to issue a level 2 alert.

The island exploded in 1883, killing approximately 40,000 people, although some estimates put the death toll much higher. The explosion is considered to be the loudest sound ever heard in modern history, with reports of it being heard nearly 3,000 miles (4,800 km) from its point of origin. The shock wave from the explosion was recorded on barographs around the globe.

http://www.irishweatheronline.com/news/earth-science/geology/exclusion-zone-set-up-around-indonesias-anak-krakatau-child-of-krakatoa/41012.html

Reykjanes Ridge Earthquakes Coincide With Rise In Seismic Activity At Katla Volcano

By MARK DUNPHY – Fri Oct 07, 12:05 pm

Reykjanes Ridge and Katla marked on Google Earth

Reykjanes Ridge and Katla marked on Google Earth

The Reykjanes Ridge, the part of the Mid-Atlantic Ridge that rises up to the ocean surface to the southwest of Iceland, has been hit by a series of earthquakes during the past 48 hours. The quakes have coincided with a surge in seismic activity in the vicinity of the Katla volcano in the south of Iceland.

The European Mediterranean Seismological Center (EMSC) has recorded at least eight subsea earthquakes about 850 kilometres southwest of the Icelandic capital of SW Reykjavík (pop 113,906).

The strongest of the quakes, a magnitude 5.7, was located 892 km southwest of the Icelandic capital Reykjavík. It hit at 00:39 GMT and was measured at a depth of just 10km, according to the EMSC.

Meanwhile, the Icelandic Meteorological Office noted that an earthquake swarm occurred underneath theMýrdalsjökull glacier in south Iceland on Wednesday and Thursday.

Approximately 30-40  earthquakes were recorded on Wednesday and Thursday. The strongest earthquake measured ML3.55 and was measured to have hit at a depth of 1 kilometre.  Seismic activity has since subsided. Only six earthquakes have been recorded at Mýrdalsjökull between 0000hrs and 1200hrs on Friday.

Geophysicist Benedikt Ófeigsson told visir.is said that while the situation is being constantly monitored, it has not been considered necessary to alert Iceland’s Civil Defense Department.

In recent weeks residents of Vik (population 300 approx.), located at the foot of Katla, have participated in emergency evacuation drills in the event of a volcanic eruption and subsequent glacial floods  affecting the small coastal town.

Read more: http://www.irishweatheronline.com/news/earth-science/geology/reykjanes-ridge-earthquakes-coincide-with-rise-in-seismic-activity-at-katla-volcano/40983.html

Rena oil spill an unfortunate lesson

Blogpost by Nathan Argent – October 7, 2011 at 16:40

The Container ship Rena inexplicably crashed into the Astrolabe Reef, about seven kilometres north of Motiti Island, near Tauranga early on Wednesday. It is carrying 1700 tonnes of heavy fuel oil, some of which has already started to leak into the sea.

Since then, fears of a potential environment disaster have grown as the leaking oil has spread threatening wildlife, including whales, birds and seals. Indeed, Environment Minister Nick Smith was quoted as saying that the spill from the ship “had the potential to be New Zealand’s most significant maritime pollution disaster in decades”. This is very disturbing news.

Oiled seabirds have already been found dead close to the Rena and more birds have been spotted in the water, covered in oil. It is also potentially disastrous for the blue whales and dolphins presently calving in the area, as well as numerous other marine species.

Response teams have so far been unable to deploy oil booms to contain the spill. The response so far as been to use a dispersant called Corexit  9500 – which is being sprayed on the water to disperse the oil. Corexit is the same chemical used in the Gulf of Mexico to deal with the oil from BP’s Deepwater Horizon spill.

Unfortunately ‘dispersal’ essentially means never cleaning up the oil. It will just stay out there and continue to pollute the marine environment. The reason being that Corexit acts like a surfactant and attracts the oil. The oil then forms globules and sinks to the bottom.

Some studies have shown that Corexit 9500 is four times as toxic as the oil itself.  Both are now going into the ocean water. It’s not a good situation.

As the authorities battle to get the spill under control and mitigate against the worst environmental effects, we also hope that this incident gives the Government pause for thought with regards to it’s deepwater oil drilling plans. This accident is an unfortunate reminder of just how difficult it is to deal with oil spills at sea. It’s a slow spill in a relatively accessible place, and the weather and sea conditions have been favourable yet even so, it is testing NZ’s response capability to the limits.

It’s shaping up to be a significant disaster but, bad as it is, it will be a walk in the park compared to what would happen if we had a Deepwater Horizon type spill.

Greenpeace has offered Maritime NZ the support of our inflatable boats, experienced drivers and volunteers to assist in the oil clean up and the New Zealand Wildlife Health Centre is calling for volunteers to assist in the recovery and rehabilitation of oiled wildlife but as yet there is little anyone can do.

Despite the best intentions, the oil spill response team in Tauranga will not be able to do enough. There is no ‘enough’.

The tools we have to respond to oil spills are orders of magnitude too small to combat the damage they do. We can’t fix oil spills; we can only prevent them. And we can only prevent the really catastrophic spills by saying no to deep sea oil drilling.

Sign the no deep sea oil petition here

http://www.greenpeace.org/new-zealand/en/news/blog/rena-oil-spill-an-unfortunate-lesson/blog/37226/

M 6.5 – SOUTH OF KERMADEC ISLANDS

A magnitude 6.5 ( downgraded to 6.1 by USGS) struck South of the Kermedic Islands.

Mw 6.5RegionSOUTH OF KERMADEC ISLANDSDate time2011-10-07 08:58:25.0 UTCLocation32.39 S ; 178.84 WDepth10 kmDistances746 km NE Tauranga (pop 110,338 ; local time 21:58:25.8 2011-10-07)
727 km NE Whakatane (pop 18,602 ; local time 21:58:25.8 2011-10-07)
702 km NE Whitianga (pop 3,367 ; local time 20:58:25.8 2011-10-07)

http://www.emsc-csem.org/Earthquake/earthquake.php?id=238314

Sharp Series of Earthquakes in Katla Volcano

A sharp series of earthquakes began shortly before 3 am last night in the northern Katla caldera below Mýrdalsjökull glacier in south Iceland with the first quake measuring well over three points on the Richter scale, according to geophysicist Benedikt Ófeigsson who was called out to the Icelandic Meteorological Office.

myrdalsjokull02_go

Mýrdalsjökull. Photo by Geir Ólafsson.

Ófeigsson said a few other earthquakes measuring around three points on the Richter scale followed but activity then subsided, only to pick up again at 3:30 am and again at 5:30 am, but in both those instances the earthquakes were weaker than during the first series, visir.is reports.

Therefore, it was not considered necessary to alert the Civil Defense Department, Ófeigsson explained, although the events of the night will be reviewed there this morning.

The inhabitants of Vík in south Iceland have drilled evacuation procedures in case of an eruption in Katla, as a glacial outburst from Mýrdalsjökull might flood the town.

http://www.icelandreview.com/icelandreview/daily_news/Sharp_Series_of_Earthquakes_in_Katla_Volcano_0_382875.news.aspx

Volcano alert level not raised despite sulphur smell: Ruapehu

GNS Science says the volcanic alert level at Ruapehu remains at 1, despite the temperature of the crater lake rising towards conditions typical for an eruption.

Skiers on the Whakapapa ski field in the central North Island have reported smelling hydrogen sulphide gas in recent weeks.

Volcanologist Brad Scott says this is because the temperature of the crater lake is cooler, which tends to produce more gas.

The latest Volcanic Alert Bulletin says the lake’s temperature on 29 September was 17.6 degrees Celsius. In March, the temperature peaked at 41 degrees Celsius.

Mr Scott says the lake is heading towards a temperature where volcanic activity typically occurs, but doesn’t always. Ruapehu is an active volcano and future eruptions may occur with little or no warning.

The eruption detection system on the mountain functioned well during a test last week, he says.

Copyright © 2011, Radio New Zealand

http://www.radionz.co.nz/news/national/87322/volcano-alert-level-not-raised-despite-sulphur-smell

Massive Japan Earthquake Altered Earth’s Gravity

Earth gravity map

ESA’s GOCE mission has delivered the most accurate model of the ‘geoid’ ever produced. Red corresponds to points with higher gravity, and blue to points with lower gravity. CREDIT: ESA/HPF/DLR

The devastating earthquake that struck Japan earlier this year was powerful enough to slightly alter the pull of gravity under the affected area, scientists now find.

Anything that has mass has a gravity field that attracts objects toward it. The strength of this field depends on a body’s mass. Since the Earth’s mass is not spread out evenly, this means its gravity field is stronger in some places and weaker in others.

The magnitude 9.0 Tohoku-Oki temblor in March was the most powerful earthquake to hit Japan and the fifth-most powerful quake ever recorded. To see how the temblor might have deformed the Earth there, scientists used the Gravity Recovery and Climate Experiment (GRACE) satellites to analyze the area’s gravity field before and after the quake.

The researchers found the Tohoku-Oki quake reduced the gravity field there by an average of two- millionths of a gal by slightly thinning the Earth’s crust. In comparison, the strength of the gravitational pull at the Earth’s surface is, on average, 980 gals. (The gal, short for Galileo, is a unit of acceleration; one gal is defined as one centimeter per second squared.)

“The most important implication of our findings is that the massive Tohoku-Oki earthquake brings significant changes to not only the ground but also the underground structure of Japan,” researcher Koji Matsuo, a geophysicist at Hokkaido University in Japan, told OurAmazingPlanet.

The GRACE satellites had previously detected gravity changes caused by the magnitude 9.1 to 9.3 2004 Sumatra-Andaman quake, the third-most powerful earthquake ever recorded, and the magnitude 8.8 earthquake that hit Chile in 2010, the eighth-most powerful on record. These reduced the gravity fields in the areas struck in much the same way as the Tohoku-Oki quake, since they were all similar types of earthquakes.

The researchers are now interested in seeing if they can detect post-quake gravity field changes as the crust settles back into place.

Matsuo and his colleague Kosuke Heki detailed their findings online Sept. 22 in the journal Geophysical Research Letters.

http://www.ouramazingplanet.com/japan-earthquake-altered-earth-gravity-2073/

Earthquakes in Australia

BY:EMMA YOUNG | OCTOBER-6-2011

Earthquakes don’t only occur near our neighbours Japan and New Zealand – they’re common in Australia too.

Earthquakes in Australia are quite common, despite its being in the middle of a tectonic plate. (Michael Payne)
Earthquakes in Australia are quite common, despite its being in the middle of a tectonic plate. (Michael Payne)

WHEN THE GROUND BEGAN to shudder, Gavin Corica didn’t worry about it – at least not at first.

“It’s not uncommon in Kalgoorlie to feel the ground vibrate because of the mining activity,” says the physiotherapist, who until recently had a practice in the West Australian town. “But then I thought that the morning was an unusual time for a blast – and then the ground started to shake sideways.”

A few seconds after that, it felt as though someone was driving a truck through the front of the building, he says. “I could hear all these sounds, like massive three-tonne boulders falling and crashing on the ground, and the lights went out. That’s when I, and the patient I was with, looked at each other and pretty much ran for the doorway.”

It was 8.17am on 20 April 2010, and an earthquake measuring magnitude 5.0 on the Richter scale was ripping apart the earth 10km south-west of Kalgoorlie. People reported feeling the earthquake up to 200km away, and, like Gavin’s building, many others within a 10km radius were badly damaged.

Most of the world’s earthquakes happen at so-called plate boundaries – parts of the planet where tectonic plates are pushing against one another – and about 80 per cent occur around the edge of the Pacific Plate (the ‘Rim of Fire’), affecting New Zealand, Japan, the west coast of North and South America and New Guinea.

A 6.3 earthquake with a shallow epicentre struck 10km south-east of Christchurch on New Zealand’s South Island in February 2011, turning much of the city centre to rubble and killing 181 people, while a huge, magnitude 9.0 quake (possibly the fourth most powerful ever recorded) struck off the coast of Japan in March creating a tsunami that killed an estimated 25,000 people, wiped entire towns off the map, and caused the largest nuclear disaster in history.

Australia doesn’t sit on the edge of a tectonic plate. However, the Indo-Australian plate, at the centre of which our continent lies, is being pushed to the north-east at about 7cm per year. It’s colliding with the Eurasian, Philippine and Pacific plates, causing stress to build up in the 25km-thick upper crust. This build-up of pressure within the plate can cause earthquakes in Australia.

Australia’s earthquakes

In fact, Australia has more quakes than other regions that sit in the middle of plates and are considered relatively stable, such as the eastern USA. “The level of seismicity does seem to be significantly higher here,” says Professor Phil Cummins, an expert on quakes at Geoscience Australia (GA) and the Australian National University’s Centre for Natural Hazards. “But no-one really knows why that is.”

According to recent research by GA, there’s been about one earthquake measuring magnitude 2.0 or greaterevery day in Australia during the past decade. “There are likely to be many more smaller earthquakes that we cannot locate because they’re not recorded on a sufficient number of seismograph stations,” says Clive Collins, a senior GA seismologist.

Western Australia is a quake hotspot, with more quakes than all the other states and territories combined. But the GA data show that Adelaide has the highest risk of any capital. It’s suffered more medium-sized quakes in the past 50 years than any other (including one that struck in March 1954, just before the visit of Queen Elizabeth II) – and that’s because it’s being squeezed sideways.

In regions around plate boundaries, it’s possible to predict roughly when quakes are likely to happen, as scientists know where to look for any build-up of stresses. “We can’t predict with an accuracy that would be valuable for evacuation or early warning,” says Phil, “but we can forecast pretty well that certain parts of the plate boundary might be more likely to experience an earthquake in the next 10-20 years than others.” But for regions that sit in the middle of a plate, like Australia, quakes can strike anywhere, making prediction practically impossible.

Thankfully, most of our quakes are small, and go unnoticed, except by seismologists. But tremors of the size that terrified the residents of Kalgoorlie last August happen about every 1-2 years, and about every five years there’s a potentially devastating quake of magnitude 6.0 or more. The biggest quake ever recorded in Australia was in 1941, at Meeberrie in WA, with an estimated  magnitude of 7.2 – but it struck a remote, largely unpopulated area.

Read more: http://www.australiangeographic.com.au/journal/earthquakes-in-australia-more-common-than-you-think.htm