|  Author | Topic: Earthquakes II (Read 6,326 times) |
Big Bunny
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|  | Re: Earthquakes II
« Reply #15 on Oct 11, 2008, 11:14am » | |
Latest significant seismic activity:
DATE LAT LON MAG DEPTH REGION
11-OCT-2008 10:40:14 19.15 -64.81 6.1 29.3 VIRGIN ISLANDS
http://www.iris.edu/seismon/
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"All truth passes through three stages. First, it is ridiculed, second it is violently opposed, and third, it is accepted as self-evident."
Arthur Schopenhauer, Philosopher, 1788-1860
"In the final analysis, our most basic common link is that we all inhabit this small planet, breathe the same air, and we all cherish our children’s future."
John F. Kennedy |
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Big Bunny
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| | Re: Earthquakes II
« Reply #16 on Oct 16, 2008, 5:14pm » | |
Latest significant seismic activity:
DATE LAT LON MAG DEPTH REGION
16-OCT-2008 19:41:32 14.56 -92.41 6.5 75.2 NEAR COAST OF CHIAPAS, MEXICO
10-OCT-2008 10:30:34 11.20 -86.54 4.8 75.1 NEAR COAST OF NICARAGUA
04-OCT-2008 18:50:35 14.61 -93.03 4.6 69.0 NEAR COAST OF CHIAPAS, MEXICO
http://www.iris.edu/seismon/
|
"All truth passes through three stages. First, it is ridiculed, second it is violently opposed, and third, it is accepted as self-evident."
Arthur Schopenhauer, Philosopher, 1788-1860
"In the final analysis, our most basic common link is that we all inhabit this small planet, breathe the same air, and we all cherish our children’s future."
John F. Kennedy |
|
Big Bunny
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| | Re: Earthquakes II
« Reply #17 on Oct 19, 2008, 7:16am » | |
Latest significant seismic activity:
DATE LAT LON MAG DEPTH REGION
19-OCT-2008 05:10:36 -21.75 -173.91 7.1 42.6 TONGA ISLANDS
18-OCT-2008 10:26:41 -20.52 -177.89 4.7 535.7 FIJI ISLANDS REGION
14-OCT-2008 16:52:52 -21.49 -178.14 5.0 404.1 FIJI ISLANDS REGION
13-OCT-2008 15:56:53 -20.77 -178.91 4.8 607.5 FIJI ISLANDS REGION
13-OCT-2008 12:07:48 -21.20 -174.66 5.1 46.4 TONGA ISLANDS
http://www.iris.edu/seismon/
|
"All truth passes through three stages. First, it is ridiculed, second it is violently opposed, and third, it is accepted as self-evident."
Arthur Schopenhauer, Philosopher, 1788-1860
"In the final analysis, our most basic common link is that we all inhabit this small planet, breathe the same air, and we all cherish our children’s future."
John F. Kennedy |
|
Big Bunny
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| | Re: Earthquakes II
« Reply #18 on Oct 19, 2008, 9:34am » | |
Mathematicians Put Forward Model For Studying Submarine Avalanches And Tsunamis
ScienceDaily (Oct. 16, 2008) — A team of Andalucian and French scientists has put forward a mathematical model that enables submarine avalanches and certain types of tsunamis to be studied using equations, according to a recent article. Mathematicians are already applying the model to analyse landslides on the island of Alborón (Almería).
“The model we have developed can be used to predict tsunamis that form following the sudden fall of sediments near the coast”, Enrique D. Fernández Nieto explains, who is one of the authors of the study and is from the Department of Applied Mathematics from the University of Seville. Rock-fall can be favoured by the existence of an abrupt slope at the bottom of the rock-fall, by an accumulation of material, or by a strong surge that destabilises the layer of sediments and causes it to fall.
The study uses equations known as “Savage-Hutter equations” named after the two scientists who proposed these in order to study rock avalanches. “However, for the first time we are addressing the need to take into account the coupling between the two layers implicated in the processes of submarine avalanches: water and rocks”. This is how Fernández describes it and also considers that studying this two-layer coupling “is complicated, but fundamental to the total dynamic, because rock movements cause the water to move, and possibly the tides of water that can displace granular material”.
Like columns of water and sand
In order to derive the model, the mathematicians took into account the porosity of the sediments, the forces that interact in the process and the “Coulomb friction term”, which refers to the parameters of the equation that are opposed to the movement of the mass of rock when it falls.
In order to understand this concept, Fernández cites the example of a column of water in a container, the door of which is opened: the liquid spills out and is directed towards a horizontal, constant and still surface. However, when the same experiment is performed with a column of sand grains, the final state has the shape of a bell. The terms that produce this resulting slope, which is no longer horizontal, due to the friction between the particles, is what is referred to as the “Coulomb friction term”.
In addition to the internal friction angles and at the bottom, the mathematicians evaluate other parameters such as the flotability of the submerged material, the topography of the land, the initial direction of the water and its height. Once all these data have been obtained, the mathematicians introduce these into a computer programme and by using animations analyse and visualise the evolution of the submarine avalanches and tsunamis.
The researchers have established the effectiveness of their equations using data from a very well documented tsunami that occurred in Papua New Guinea in 1998. In partnership with geologists from the Spanish Institute of Oceanography (IEO) and by means of a joint project financed by the Junta de Andalucia, the researchers are studying the period during which certain landslides occurred in the past in the vicinity of the Island of Alborán (Almería), and are also evaluating the likelihood of their recurring in the future in the Alborán marine basin.
Scientists from the University of Seville, the University of Malaga, the Escuela Normal Superior in Paris, the University of Savoie, also in France, and from the Seismology Team from the Institute of Physics from the Globe of Paris have all participated in the study.
Journal reference:
1. Fernandeznieto et al. A new Savage-Hutter type model for submarine avalanches and generated tsunami. Journal of Computational Physics, 2008; 227 (16): 7720 DOI: 10.1016/j.jcp.2008.04.039
http://www.sciencedaily.com/releases/2008/10/081016084059.htm
|
"All truth passes through three stages. First, it is ridiculed, second it is violently opposed, and third, it is accepted as self-evident."
Arthur Schopenhauer, Philosopher, 1788-1860
"In the final analysis, our most basic common link is that we all inhabit this small planet, breathe the same air, and we all cherish our children’s future."
John F. Kennedy |
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Big Bunny
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| | Re: Earthquakes II
« Reply #19 on Oct 20, 2008, 3:29am » | |
Latest significant seismic activity:
DATE LAT LON MAG DEPTH REGION
20-OCT-2008 04:54:20 0.10 120.69 6.0 105.4 MINAHASSA PENINSULA, SULAWESI
15-OCT-2008 16:35:51 -6.52 129.51 4.6 172.3 BANDA SEA
http://www.iris.edu/seismon/
|
"All truth passes through three stages. First, it is ridiculed, second it is violently opposed, and third, it is accepted as self-evident."
Arthur Schopenhauer, Philosopher, 1788-1860
"In the final analysis, our most basic common link is that we all inhabit this small planet, breathe the same air, and we all cherish our children’s future."
John F. Kennedy |
|
Big Bunny
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| | Re: Earthquakes II
« Reply #20 on Oct 22, 2008, 7:21pm » | |
Latest significant seismic activity:
DATE LAT LON MAG DEPTH REGION
22-OCT-2008 17:03:47 -24.65 -178.84 5.2 373.5 SOUTH OF FIJI ISLANDS
22-OCT-2008 12:55:57 -18.38 -175.40 6.3 227.4 TONGA ISLANDS
22-OCT-2008 09:10:39 -26.08 -177.60 4.8 168.5 SOUTH OF FIJI ISLANDS
19-OCT-2008 14:14:39 -21.86 -173.84 4.9 68.1 TONGA ISLANDS
19-OCT-2008 12:55:05 -21.94 -173.73 5.8 35.0 TONGA ISLANDS
19-OCT-2008 05:10:36 -21.75 -173.91 7.1 42.6 TONGA ISLANDS
18-OCT-2008 10:26:41 -20.52 -177.89 4.7 535.7 FIJI ISLANDS REGION
14-OCT-2008 16:52:52 -21.49 -178.14 5.0 404.1 FIJI ISLANDS REGION
13-OCT-2008 15:56:53 -20.77 -178.91 4.8 607.5 FIJI ISLANDS REGION
13-OCT-2008 12:07:48 -21.20 -174.66 5.1 46.4 TONGA ISLANDS
http://www.iris.edu/seismon/
|
"All truth passes through three stages. First, it is ridiculed, second it is violently opposed, and third, it is accepted as self-evident."
Arthur Schopenhauer, Philosopher, 1788-1860
"In the final analysis, our most basic common link is that we all inhabit this small planet, breathe the same air, and we all cherish our children’s future."
John F. Kennedy |
|
Big Bunny
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| | Re: Earthquakes II
« Reply #21 on Oct 23, 2008, 11:36pm » | |
Latest significant seismic activity:
DATE LAT LON MAG DEPTH REGION
23-OCT-2008 10:04:36 -2.61 145.64 6.2 10.0 ADMIRALTY ISLANDS REGION, P.N.G.
22-OCT-2008 04:51:54 -7.29 154.83 5.0 102.1 SOLOMON ISLANDS
20-OCT-2008 23:15:46 -3.38 149.99 5.0 35.0 BISMARCK SEA
19-OCT-2008 23:29:15 -3.53 140.00 4.9 65.8 IRIAN JAYA, INDONESIA
18-OCT-2008 00:54:41 -6.95 147.25 5.8 87.1 EASTERN NEW GUINEA REG., P.N.G.
16-OCT-2008 23:24:43 -3.74 150.43 5.0 35.0 NEW IRELAND REGION, P.N.G.
16-OCT-2008 16:02:00 -3.98 150.61 4.8 71.2 NEW IRELAND REGION, P.N.G.
16-OCT-2008 16:00:10 -4.08 150.55 4.7 85.1 NEW BRITAIN REGION, P.N.G.
16-OCT-2008 15:58:22 -4.00 150.45 4.6 86.0 NEW BRITAIN REGION, P.N.G.
http://www.iris.edu/seismon/
|
"All truth passes through three stages. First, it is ridiculed, second it is violently opposed, and third, it is accepted as self-evident."
Arthur Schopenhauer, Philosopher, 1788-1860
"In the final analysis, our most basic common link is that we all inhabit this small planet, breathe the same air, and we all cherish our children’s future."
John F. Kennedy |
|
Big Bunny
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| | Re: Earthquakes II
« Reply #22 on Oct 24, 2008, 12:33am » | |
North Pole Exploration: Large Sliding Masses Close Beneath The Seafloor Of East-Siberian Continental Shelf Discovered
![[image]](http://img243.imageshack.us/img243/4172/081020120045large617580am6.jpg "[image]")
Aerial view of the ice-breaker "Polarstern“ (Credit: Alfred Wegener Institute)
ScienceDaily (Oct. 20, 2008) — The German research vessel Polarstern has returned today to Bremerhaven from the Arctic Sea. It has cruised as the first research vessel ever both the Northeast and the Northwest Passages and thereby circled the North Pole. The third part of the research vessel's 23rd Arctic expedition, operated by the Alfred Wegener Institute in the Helmholtz Association, started its journey on August 12th in Reykjavik and ended it on October 17th in Bremerhaven. The ship travelled a distance of 10.800 nautical miles, equivalent to 20.000 kilometres.
On board were 47 researchers from 12 nations, for example from Belgium, Germany, France, Japan, Canada, Korea, the Netherlands, Russia and the USA. Because of the small ice cover, the expedition members were able to research hitherto uncharted waters. The small sea ice cover presents a cause for concern regarding climate change in the Arctic Ocean. The aim of this expedition was to gather data on the development of the geology of the Arctic area.
The researchers around cruise leader Dr. Wilfried Jokat, geophysicist at the Alfred Wegener Institute, have discovered large sliding masses close beneath the seafloor of the East-Siberian continental shelf by means of sediment-acoustic parasound measurements. "Sliding masses are witnesses of great sediment relocations which appear, for instance, when large amounts of sediments are deposited", explains Jokat.
The continental slope becomes instable and sediments slide down. Such a large amount of sediments causing a shift can only have one reason: the sediments were frozen in the ice masses of the East-Siberian mainland, thawed during an interglacial and unloaded their sediments with the melt water into the ocean. "This is a spectacular finding. Large-scale glaciations in eastern Siberia within the younger geological past of 60.000 years and older are so far unknown", explains Prof. Dr. Rüdiger Stein, geologist at the Alfred Wegener Institute. Additional acoustic (seismic) data show that the East-Siberian Shelf was covered with ice over the last three million years only during a few glacial periods.
Further investigations are necessary to confirm this finding and particularly to time the reported events chronologically. The scientists have brought material in the form of sediment cores to Bremerhaven to achieve this. 16 soil samples could be taken on a transect of 700 kilometres from the Canada Basin via the Mendeleev Ridge into the Makarov Basin. The analysis will allow for the first time to compare the glacial history of the Northern USA and Canada with Siberia and to elaborate differences and parallels in detail. Furthermore, the data from the sediment cores can deliver information on the temporal and spatial changes of ocean currents and the extent of sea ice in the central Arctic Ocean. "We expect from these investigations important new insights into the control procedures of long and short term climate changes in the Arctic", says a delighted Stein.
Another focal point of this cruise was on the geological development of the Arctic Ocean during the last 90 million years. Seismic, an acoustic measurement method, allows peeking into the deep layers under the ocean floor down to 4.000 metres depth. "The collected data show that the ocean basin between the two Arctic ridge systems, the Lomonossov and the Mendeleev Ridge, are considerably older than estimated so far. Thus, the basins in the old part of the Arctic Ocean, the Makarov and the Canada Basin, have developed at about the same", reports Jokat. "The following detachment of the Lomonossov Ridge from the East-Siberian Shelf took place 60 million years ago – not without massive changes to the environment. The data present evidence of strong relocation processes in the deep-sea sediments", continues the geophysicist. "Many model representations about the development of the Arctic Ocean must be rethought on the basis of the new data", concludes Jokat.
Oceanographers regularly collect data on water temperature, density and salinity from the ship. Additionally, they brought out buoys on ice floes which autonomously conduct these measurements over one or two years. The oceanographers can thereby better understand how the water masses circulate in the Arctic Ocean. Integrated into long-term measurements, they can describe changing water temperatures and sea ice cover regarding climate change.
Biologists on board investigated the occurrence and distribution of the copepod Oithona similis in the Arctic Ocean. This small crab is an important part of the food web. It feeds, among other things, on small algae and animals and serves on its part as food for fish larvae. Another biological programme is aimed at collecting data on the distribution of birds, seals, whales and polar bears along the route. An almost continuous measurement of the seafloor and a programme for water probes rounded off the interdisciplinary scientific programme.
The measurements contribute to research within the framework of the International Polar Year, the European project DAMOCLES and the North Atlantic project of the German Federal Ministry of Education and Research. After the usual maintenance and repair work, Polarstern will leave on October 31st with the destination Cape town. There begins the Antarctic season 2008/09.
http://www.sciencedaily.com/releases/2008/10/081020120045.htm
|
"All truth passes through three stages. First, it is ridiculed, second it is violently opposed, and third, it is accepted as self-evident."
Arthur Schopenhauer, Philosopher, 1788-1860
"In the final analysis, our most basic common link is that we all inhabit this small planet, breathe the same air, and we all cherish our children’s future."
John F. Kennedy |
|
Big Bunny
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| | Re: Earthquakes II
« Reply #23 on Oct 27, 2008, 6:11pm » | |
21st Century Detective Work Reveals How Ancient Rock Got Off To A Hot Start
![[image]](http://img509.imageshack.us/img509/4746/0810151441317764255wz8.jpg "[image]")
Komatiites are formed from super hot molten rock. (Credit: Image courtesy of Imperial College London)
ScienceDaily (Oct. 27, 2008) — A new technique using X-rays has enabled scientists to play 'detective' and solve the debate about the origins of a three billion year old rock fragment.
In the study, published in the journal Nature, a scientist describes the new technique and shows how it can be used to analyse tiny samples of molten rock called magma, yielding important clues about the Earth's early history.
Working in conjunction with Australian and US scientists, an Imperial College London researcher analysed a magma using the Chicago synchrotron, a kilometre sized circular particle accelerator that is commonly used to probe the structure of materials.
In this case, the team used its X-rays to investigate the chemistry of a rare type of magmatic rock called a komatiite which was preserved for billions of years in crystals.
It has previously been difficult to discover how these komatiites formed because earlier analytical techniques lacked the power to provide key pieces of information.
Now, thanks to the new technique, the team has found that komatiites were formed in the Earth's mantle, a region between the crust and the core, at temperatures of around 1,700 degrees Celsius, more than 2.7 billion years ago.
These findings dispel a long held alternative theory which suggested that komatiites were formed at much cooler temperatures, and also yields an important clue about the mantle's early history. They found that the mantle has cooled by 300 degrees Celsius over the 2.7 billion year period
Lead researcher, Dr Andrew Berry, from Imperial College London's Department of Earth Science and Engineering, says more research needs to be done to understand fully the implications of this finding. However, he believes this new technique will enable scientists to uncover more details about the Earth's early history. He says:
"It has long been a 'holy grail' in geology to find a technique that analyses the chemical state of tiny rock fragments, because they provide important geological evidence to explain conditions inside the early Earth. This research resolves the controversy about the origin of komatiites and opens the door to the possibility of new discoveries about our planet's past."
In particular, Dr Berry believes this technique can now be used to explain Earth's internal processes such as the rate at which its interior has been cooling, how the forces affecting the Earth's crust have changed over time, and the distribution of radioactive elements which internally heat the planet.
He believes this information could then be used to build new detailed models to explain the evolution of the planet. He concludes:
"It is amazing that we can look at a fragment of magma only a fraction of a millimetre in size and use it to determine the temperature of rocks tens of kilometres below the surface billions of years ago. How's that for a piece of detective work?"
Journal reference:
1. Berry et al. Oxidation state of iron in komatiitic melt inclusions indicates hot Archaean mantle. Nature, October 16, 2008; 455 (7215): 960 DOI: 10.1038/nature07377
http://www.sciencedaily.com/releases/2008/10/081015144131.htm
|
"All truth passes through three stages. First, it is ridiculed, second it is violently opposed, and third, it is accepted as self-evident."
Arthur Schopenhauer, Philosopher, 1788-1860
"In the final analysis, our most basic common link is that we all inhabit this small planet, breathe the same air, and we all cherish our children’s future."
John F. Kennedy |
|
Big Bunny
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| | Re: Earthquakes II
« Reply #24 on Oct 28, 2008, 9:12pm » | |
Latest significant seismic activity:
DATE LAT LON MAG DEPTH REGION
28-OCT-2008 16:00:06 -3.58 145.86 6.0 35.0 NEAR N COAST OF NEW GUINEA, PNG.
23-OCT-2008 10:04:36 -2.61 145.64 6.2 10.0 ADMIRALTY ISLANDS REGION, P.N.G.
22-OCT-2008 04:51:54 -7.29 154.83 5.0 102.1 SOLOMON ISLANDS
20-OCT-2008 23:15:46 -3.38 149.99 5.0 35.0 BISMARCK SEA
19-OCT-2008 23:29:15 -3.53 140.00 4.9 65.8 IRIAN JAYA, INDONESIA
18-OCT-2008 00:54:41 -6.95 147.25 5.8 87.1 EASTERN NEW GUINEA REG., P.N.G.
16-OCT-2008 23:24:43 -3.74 150.43 5.0 35.0 NEW IRELAND REGION, P.N.G.
16-OCT-2008 16:02:00 -3.98 150.61 4.8 71.2 NEW IRELAND REGION, P.N.G.
16-OCT-2008 16:00:10 -4.08 150.55 4.7 85.1 NEW BRITAIN REGION, P.N.G.
16-OCT-2008 15:58:22 -4.00 150.45 4.6 86.0 NEW BRITAIN REGION, P.N.G.
http://www.iris.edu/seismon/
|
"All truth passes through three stages. First, it is ridiculed, second it is violently opposed, and third, it is accepted as self-evident."
Arthur Schopenhauer, Philosopher, 1788-1860
"In the final analysis, our most basic common link is that we all inhabit this small planet, breathe the same air, and we all cherish our children’s future."
John F. Kennedy |
|
Big Bunny
Admin
member is offline
Joined: Apr 2003
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Posts: 50,820
Location: Sydney, Australia
| | Re: Earthquakes II
« Reply #25 on Oct 28, 2008, 9:13pm » | |
Latest significant seismic activity:
DATE LAT LON MAG DEPTH REGION
29-OCT-2008 15:32:45 30.38 67.57 4.1 10.0 PAKISTAN
29-OCT-2008 11:32:42 30.54 67.46 6.2 10.0 PAKISTAN
29-OCT-2008 00:31:57 30.62 67.51 4.6 10.0 PAKISTAN
28-OCT-2008 23:54:18 31.05 67.79 4.0 10.0 AFGHANISTAN
28-OCT-2008 23:09:57 30.75 67.34 6.2 10.0 PAKISTAN
28-OCT-2008 22:33:09 30.61 67.44 5.2 12.1 PAKISTAN
26-OCT-2008 01:28:54 36.51 70.64 5.6 189.1 HINDU KUSH REGION, AFGHANISTAN
23-OCT-2008 05:50:51 39.63 74.00 4.9 52.7 SOUTHERN XINJIANG, CHINA
21-OCT-2008 15:09:12 31.62 77.33 4.3 35.4 NORTHERN INDIA
20-OCT-2008 05:21:45 36.18 71.20 4.6 95.0 AFGHANISTAN-TAJIKISTAN BORD REG.
18-OCT-2008 09:29:00 39.47 73.63 4.8 10.0 TAJIKISTAN-XINJIANG BORDER REG.
http://www.iris.edu/seismon/
Further:
Heavy casualties reported after quake
Article from: Agence France-Presse
From Islamabad, Pakistan
October 29, 2008 02:41pm
AT least 40 people were killed in a 6.2-magnitude earthquake that struck today in southwestern Pakistan, near its border with Afghanistan, police say.
The quake hit around 70km northeast of the Pakistani city of Quetta and around 185km southeast of the Afghan city of Kandahar early this morning, the US Geological Survey said.
The tremor sent people running screaming from their homes in Quetta, according to witnesses in the city.
Television pictures showed local people outside in the streets, wrapped up against the early morning chill.
The deaths occurred in and around the hilly town of Ziarat, about 50km east of Quetta, in gas-rich Baluchistan province, police official Abdul Khaleq said.
"We have confirmed reports of more than 40 people dead when their homes collapsed in the earthquake,'' he said.
A woman was also killed in Pishin district to the west of Quetta, another police official said.
Several people were injured in the panic in Quetta, with one person hurting their legs after jumping from a first floor window and three people wounded when people fired guns in the air after the quake, hospital officials said.
The Pakistani military said it was still assessing the damage.
"We have received reports of heavy casualties, we can't confirm how many,'' Quetta-based army spokesman Major Shabahat Hussain said.
Army troops and two helicopters have been sent from Quetta to Ziarat and an assessment of the damage was also under way, another military spokesman said.
Ziarat is a historic hill resort famed for its juniper forests.
It receives visitors from all over Pakistan in summer who come to see the holiday residence of the country's founder, Mohammed Ali Jinnah.
Most of the casualties were from two villages on the outskirts of the town which were built on steep ground and badly damaged in landslides triggered by the quake, which struck at a depth of 10km, officials said.
Local government officials said they had called for paramedics and rescuers.
The Pakistan Meteorological Office put the magnitude of the quake at 6.3.
http://www.news.com.au/dailytelegraph/story/0,22049,24570560-5001028,00.html
|
"All truth passes through three stages. First, it is ridiculed, second it is violently opposed, and third, it is accepted as self-evident."
Arthur Schopenhauer, Philosopher, 1788-1860
"In the final analysis, our most basic common link is that we all inhabit this small planet, breathe the same air, and we all cherish our children’s future."
John F. Kennedy |
|
Big Bunny
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| | Re: Earthquakes II
« Reply #26 on Oct 29, 2008, 7:48pm » | |
Tsunami in 2004 'not the first'
By Jason Palmer
Science and Technology reporter, BBC News
![[image]](http://img207.imageshack.us/img207/4316/45153605117601378bb8.jpg "[image]")
Before and after photos show the sediment coverage after the 2004 tsunami
The Indian Ocean tsunami in 2004 was not the first of its size to hit the region, according to new research.
Two international collaborations have sampled the sediments in Thailand and Sumatra to examine tsunami history.
At both sites, there was evidence of sediment laid down by a large tsunami between 600 and 700 years ago, pre-dating written and oral records.
The findings, reported in Nature, could be used to put statistical weight behind estimates of future tsunami.
The surge of a tsunami brings with it a great deal of sediment that rushes inland; the bigger the tsunami, the deeper and further inland the layer of sediment it leaves behind.
In locations where those deposits aren't disturbed by wind or running water, they can be used as a historical record of these powerful events after more layers are added.
The study of these layers in coastal regions has revealed instances of tsunami elsewhere in the world, including a prehistoric event that inundated the Shetland and Orkney islands off Scotland.
To investigate the tsunami record in the Indian Ocean basin, two research groups took core samples that capture the layers of sediment below the surface.
One group, led by Kruawun Jankaew of Chulalongkorn University in Thailand, sampled 150 sites on Phra Thong, a barrier island off the west coast of Thailand. Another group headed up by Katrin Monecke, now at the University of Pittsburgh, sampled 100 sites in the Aceh region in the north of Sumatra.
In both locations, a deep sandy layer was found beneath the surface, matching the top layer of sand left from the 2004 tsunami. By using radiocarbon dating to estimate the age of the buried sand layer, both teams found that they came from 600-700 years ago.
Dr Monecke's team also found evidence of a deeper sandy layer, with a corresponding age of about 1,200 years, suggesting a "recurrence time" for large tsunami of around 600 years.
Those buried layers occurred as far inland as those on the surface, suggesting that the tsunami that deposited them centuries ago was of roughly the same size as the 2004 event.
The team in Thailand found some suggestion of the 1,200 year-old layer and more substantial evidence for layers corresponding to around 2,000 years ago.
Timely results
Though the earthquakes that drive tsunami don't happen predictably, the results, reported in the journal Nature, suggest that another tsunami of that scale will not occur in the near future.
Roger Musson of the British Geological Survey says that the findings are "not only interesting but useful because from a point of view of understanding the hazard. It's important to know what the recurrence time is."
"Geological data is increasingly being used to back up forecasts of how likely there is to be large earthquakes in the future."
From Dr Monecke's point of view, that kind of information can serve as a basis for tsunami education in the region. That, she says, could contribute to policy decisions in the near term.
"For coastal planners I think it's very important to know this," Dr Monecke told BBC News.
"We saw that whole villages were being relocated 10km [6 miles] inland, and these people are mainly fishermen.
"You have to balance this; would it be better to be that far away so that if in a few generations, another tsunami hits, and they are that far away, or would it be better to stay at the coastline and be prepared for it?"
Story from BBC NEWS:
http://news.bbc.co.uk/go/pr/fr/-/2/hi/science/nature/7697482.stm
Published: 2008/10/29 18:00:46 GMT
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"All truth passes through three stages. First, it is ridiculed, second it is violently opposed, and third, it is accepted as self-evident."
Arthur Schopenhauer, Philosopher, 1788-1860
"In the final analysis, our most basic common link is that we all inhabit this small planet, breathe the same air, and we all cherish our children’s future."
John F. Kennedy |
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Big Bunny
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| | Re: Earthquakes II
« Reply #27 on Oct 30, 2008, 6:54pm » | |
Quakes give trampoline effect: Japanese study
Posted 2008/10/30 at 3:06 pm EDT
HONG KONG, Oct. 30, 2008 (Reuters) — Earthquakes not only shake the ground from side to side, they hoist it up and down as though the earth is bouncing on a trampoline, researchers in Japan found.
The scientists found evidence of the jarring vertical movements from analyzing data recorded by seismographs during a powerful earthquake that struck northern Japan on June 14.
That 7.2 magnitude quake struck a remote hot spring resort, killed at least 9 people and left more than 200 injured.
The scientists likened the vertical movement of the quake to an athlete bouncing on a trampoline.
"There are two forces acting on the athlete, namely the downward-directed gravity and the upward-directed repulsion of the trampoline hit by the athlete," they wrote in the article published in the journal Science.
"The trampoline's repellent force is larger than gravity," they said leading to vertical movements.
They hoped the findings would help engineers design buildings that can withstand strong motion, both horizontal and vertical, in earthquake-prone zones.
http://www.newsdaily.com/stories/tre49t8ja-us-earthquakes-trampoline/
|
"All truth passes through three stages. First, it is ridiculed, second it is violently opposed, and third, it is accepted as self-evident."
Arthur Schopenhauer, Philosopher, 1788-1860
"In the final analysis, our most basic common link is that we all inhabit this small planet, breathe the same air, and we all cherish our children’s future."
John F. Kennedy |
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Big Bunny
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| | Re: Earthquakes II
« Reply #28 on Oct 31, 2008, 11:08am » | |
Indonesian Mud Volcano Triggered By Drilling Of Nearby Gas Exploration Well, Scientists Conclude
![[image]](http://img261.imageshack.us/img261/9738/081030144628large896224uv1.jpg "[image]")
The main vent of the Lusi mud volcano taken within a few months of eruption. (Credit: Durham University)
ScienceDaily (Oct. 30, 2008) — A resounding vote of international petroleum geologists from around the globe concluded that the mud volcano was triggered by drilling of a nearby gas exploration well.
This may have implications for compensation of the local population affected.
Lusi started to erupt in East Java, Indonesia, on May 29th 2006, and is still spewing huge volumes of boiling mud over the surrounding area. It has displaced around 30,000 people from their homes and swamped 12 villages.
The cause of Lusi was considered at a debate this week at an International conference in Cape Town, South Africa, which concluded with a vote between 74 world-leading petroleum scientists who considered the evidence presented by four experts in the field.
Some 42 scientists voted that gas exploration well, Banjar-Panji-1, which was being drilled by oil and gas company called Lapindo Brantas, was the cause.
Only 3 scientists voted for the alternative explanation – that the Yogyakarta earthquake two days before the eruption, whose epicentre was 280km from the mud volcano, was the cause. Some 16 scientists voted that the evidence was inconclusive and 13 that a combination of earthquake and drilling were the cause.
The vote, taken in the last week in October at the American Association of Petroleum Geologists Conference in South Africa, follows months of scientific investigation and analysis published by some of the world's leading experts in their field.
Key reasons supporting drilling rather than the earthquake as the cause include:
* the earthquake was too small and too far away to have had a role.
* the well was being drilled at the same time and only 150 m from the volcano site.
* the well took a huge influx of fluid the day before the eruption, resulting in pressures that the well could not tolerate.
* the pressure measured in the well after the influx provides strong evidence that the well was leaking and even evidence for the initial eruption at the surface.
One of the speakers, leading geologist Professor Richard Davies of Durham University, UK, commented: "The conference allowed us to present new data on the pressures in the well the day before the eruption and these provide a compelling tape recording of the well as it started to leak.''
"We were particularly grateful to Lapindo, the company involved in the drilling, who were widely applauded at the meeting for their willingness to take part in the discussion."
Prof Davies added: "I remain convinced that drilling was the cause of the mud volcano. The opinion of the international scientists at the event in South Africa adds further weight to my conviction and the conclusions of many other leading scientists who have studied Lusi."
Susila Lusiaga a drilling engineer and part of the Indonesian police investigation team said: "There is no question, the pressures in the well went way beyond what it could tolerate – and it triggered the mud volcano."
Michael Manga, Professor of Earth and Planetary Science at the University of California, Berkeley, said: "The key observation from an earthquake perspective is that there were many much larger and quite a bit closer earthquakes that did not trigger an eruption'.
"The Yogyakarta earthquake was simply too small and too far away to initiate an eruption."
Lusi is still flowing at 100,000 cubic metres per day, enough to fill 53 Olympic swimming pools.
Recent research by Durham University UK, and the Institute of Technology Bandung in Indonesia, showed Lusi is collapsing by at about 13 m per year and sometimes 3 m overnight and could subside to depths of more than 140 metres, having a significant environmental impact on the surrounding area for years to come.
http://www.sciencedaily.com/releases/2008/10/081030144628.htm
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"All truth passes through three stages. First, it is ridiculed, second it is violently opposed, and third, it is accepted as self-evident."
Arthur Schopenhauer, Philosopher, 1788-1860
"In the final analysis, our most basic common link is that we all inhabit this small planet, breathe the same air, and we all cherish our children’s future."
John F. Kennedy |
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Big Bunny
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| | Re: Earthquakes II
« Reply #29 on Nov 1, 2008, 4:47am » | |
Latest significant seismic activity:
DATE LAT LON MAG DEPTH REGION
01-NOV-2008 04:07:56 -3.40 148.65 5.0 10.0 BISMARCK SEA
01-NOV-2008 01:13:10 -3.40 148.54 6.0 10.0 BISMARCK SEA
28-OCT-2008 16:00:06 -3.58 145.86 6.0 35.0 NEAR N COAST OF NEW GUINEA, PNG.
23-OCT-2008 10:04:36 -2.61 145.64 6.2 10.0 ADMIRALTY ISLANDS REGION, P.N.G.
22-OCT-2008 04:51:54 -7.29 154.83 5.0 102.1 SOLOMON ISLANDS
20-OCT-2008 23:15:46 -3.38 149.99 5.0 35.0 BISMARCK SEA
19-OCT-2008 23:29:15 -3.53 140.00 4.9 65.8 IRIAN JAYA, INDONESIA
18-OCT-2008 00:54:41 -6.95 147.25 5.8 87.1 EASTERN NEW GUINEA REG., P.N.G.
16-OCT-2008 23:24:43 -3.74 150.43 5.0 35.0 NEW IRELAND REGION, P.N.G.
16-OCT-2008 16:02:00 -3.98 150.61 4.8 71.2 NEW IRELAND REGION, P.N.G.
16-OCT-2008 16:00:10 -4.08 150.55 4.7 85.1 NEW BRITAIN REGION, P.N.G.
16-OCT-2008 15:58:22 -4.00 150.45 4.6 86.0 NEW BRITAIN REGION, P.N.G.
http://www.iris.edu/seismon/
|
"All truth passes through three stages. First, it is ridiculed, second it is violently opposed, and third, it is accepted as self-evident."
Arthur Schopenhauer, Philosopher, 1788-1860
"In the final analysis, our most basic common link is that we all inhabit this small planet, breathe the same air, and we all cherish our children’s future."
John F. Kennedy |
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