On Wednesday the 11th of February Bernie Joyce, from the University of Melbourne, presented a paper on volcanic hazards at the 17th Australian Geological Convention of the Geological Society of Australia held in Hobart, Tasmania.
Professor Joyce claimed that volcanoes in eastern Australia that have not erupted in thousands of years still pose a threat and emergency services should be better prepared. Volcanoes in Victoria, New South Wales and Queensland could erupt at any time. (I can’t find any proof for the QLD eruptions).
There has been no volcanic activity in Australia in the past few hundred years, and no major eruption since Mt Gambier, on the border of South Australia and Victoria, 4500 years ago. However, a sudden eruption could still catch emergency authorities unprepared for the floods, mud flows and ash falls that could follow, said Joyce.
The kind of eruption expected in Australia is not on the same scale as the Mt Helen's eruption, (which wiped out a large area in the U.S. state of Washington in May 1980). Australia could expect a smaller eruption. "We haven't had much [volcanic] activity in the last few hundred years, so we're not quite sure what it would look like," said Joyce.
However, Joyce’s claims were disputed by Dr Wally Johnson head of the Geohazards division at Geoscience Australia.( A government organisation; think CSIRO and the sacking of scientists who claimed GMO canola would corrupt pure non GMO crops and let’s think about how much we trust information coming from GeoScience Australia.)
"If Mt Gambier did erupt it would impact on local communities," Johnson said. "But any changes to the state of these volcanoes would be noticed early on, either through earthquakes, or in the case of Mt Gambier an increase in the temperature of the water.
"We know that volcanoes do provide a fair bit of warning. In most cases this would be months or even years. You might get a volcano way out in western Victoria where you might not notice the warning signs but in most cases you'll get advance warning from geological phenomena," he said.
Advance warnings could include an increase in seismic activity, a change in the temperature of surface soils, or even smoking fumaroles, small eruptions from the side of a volcano that indicate that a major eruption was imminent.
Could our interesting and completely unexpected recent earth tremors (total conjecture here) be one of those indicators!
According to GeoScience Australia, the earthquakes that were felt in Melbourne first occurred on March 6, “This is the third largest earthquake in the Melbourne-Gippsland region for over twenty years, but an earthquake this large has not occurred this close to Melbourne since 1973. Larger earthquakes occurred at Thomson Reservoir in September 1996 and at Boolarra in August 2000.
“This type of event, called an intra-plate earthquake, occurs due to the build up of stress in the Earth’s crust, caused by the movement of the tectonic plates. This is part of the Earth’s natural dynamic processes. The Australian continent is part of the Indian-Australian plate which is being pushed slowly north-east at approximately 7cm per year, resulting in collisions with the Eurasian, Philippine and Pacific plates. The stress from these collisions is released during an earthquake,” said Dr Cummins Duty Seismologist for GeoScience Australia.
First activity:
06/03/2009 09:55:37(UTC) N of Korumburra VIC
Latitude: -38.39 Longitude: 145.79 Magnitude: 4.6 Depth(km): 8
Further activity was later that day, probably a series of after shocks.
06/03/2009 11:49:42(UTC) Korumburra VIC
Latitude: -38.466 Longitude: 145.829 Magnitude: 2.9 Depth(km): 6
06/03/2009 15:53:12(UTC) Korumburra VIC
Latitude: -38.515 Longitude: 145.771 Magnitude: 3.7 Depth(km): 13
06/03/2009 23:14:36(UTC) Korumburra VIC
Latitude: -38.443 Longitude: 145.833 Magnitude: 3.6 Depth(km): 12
A couple of days later the earthquake epicenter had remained in the same area.
09/03/2009 06:39:05(UTC) Korumburra VIC
Latitude: -38.426 Longitude: 145.829 Magnitude: 3.3 Depth(km): 14
And again four days later more activity, though much clamed
13/03/2009 17:47:09(UTC) Korumburra, VIC
Latitude: -38.423 Longitude: 145.892 Magnitude: 2.8 Depth(km): 10
18/03/2009 11:05:58(UTC) Korumburra, VIC
Latitude: -38.4164 Longitude: 145.8516 Magnitude: 3.1 Depth(km): 0
18/03/2009 08:57:55(UTC) Korumburra, VIC
Latitude: -38.3834 Longitude: 145.9485 Magnitude: 2.7 Depth(km): 2
18/03/2009 05:28:20(UTC) Korumburra, VIC
Latitude: -38.39 Longitude: 145.8 Magnitude: 4.6 Depth(km): 18
This is the one I felt at home with my windows shaking.
So far just this March there have been five volcanic eruptions around the world; Tonga and Indonesia, Chile, Alaska and Columbia. Volcanoes are quite a bit more common than we think and experts now believe that magma flows are transient and could be moving as well as plates, creating a hell of an unstable planet earth. Recent activity in the last two decades like the bombing of atolls in the pacific may be (completely unproven, totally my conjecture) further destabilizing.
Victoria has two dormant, not extinct volcanoes and these are:
Mt Eccles Volcano Victoria, Australia
Mt Eccles National Park is located 10 km west of the town of Macarthur.
It is a composite volcano with a crater lake, spatter cones, lava tubes, and tumuli.
The volcano is considered as dormant, but not yet extinct.
Mt Eccles is 179 m high.
Eruptions of Mt Eccles Volcano
6000 - 19000 years ago
Mt Napier Volcano Victoria, Australia
Mt Napier volcano is located between Mt Eccles and the town of Hamilton.
The volcano rises 150 m above the surrounding plain.
Lava from the volcano covers a large part of the Harman Valley.
Eruptions of Mt Napier Volcano
5000 - 6000 years ago.
A volcano on Australia's remote, tiny and uninhabited McDonald Island in the Southern Ocean began erupting in 1992. The volcano had stayed dormant for 75,000 years before erupting for the first time in 1992.There have been several eruptions since then, the most recent in 2001 when satellite images showed the size of the island had doubled from 1.13 to 2.45 square kilometres.
"The McDonald Island volcano is unusual because unlike most oceanic volcanoes, it sits on a submarine plateau, which means its eruptions are not as wild and fiery as some, instead producing a slow-moving mass of lava that seeps and spreads," said then Environment Minister Ian Campbell.
I ponder again the recent earth tremors. Most interestingly, during my internet searching and Google, I have come to the conclusion that among geologists it is an excepted belief that there may be volcanic activity in Victoria or South Australia possibly in our lifetimes. It is so commonly believed, it is mentioned everywhere and there are many academic sites and articles referring to this possibility. How incredible; it’s all news to me!
From home.iprimus.com.au/
Scientists believe a new Australian volcano is being created.
Geologists suspect an earthquake that originated 50 kilometres from King Island in February 2002 signalled the reawakening of the hot spot, a region in the Earth's crust where the planet expels some of its internal heat.
Australia's hot spot is several hundred kilometres wide and lies under Bass Strait and parts of Victoria and Tasmania.
Wally Johnson, a vulcanologist at Geosciences Australia, said the fact that there were earthquakes taking place in the area "means that geologically, the hot spot has to be regarded as active, even though it hasn't produced volcanic eruptions as such".
He said it could spawn a volcano within 100 years.
No comments:
Post a Comment