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|  | Earthquakes II
« Thread Started on Sept 16, 2008, 9:46am » | |
New Geomorphological Index Created For Studying Active Tectonics Of Mountains
ScienceDaily (Sep. 16, 2008) — To build a hospital, nuclear power station or a large dam you need to know the possible earthquake risks of the terrain. Now, researchers from the Universities of Granada and Jaen, alongside scientists from the University of California (Santa Barbara, USA), have developed, based on relief data from the southern edge of the Sierra Nevada, a geomorphological index that analyses land form in relation to active tectonics, applicable to any mountain chain on the planet.
Active tectonics comprise the most up-to-date deformation processes that affect the Earth's crust, resulting in earthquakes or recent deformations in the planet’s faults and folds. This phenomena is analysed in geology research carried out before commencing engineering works.
Depending on the type of project (nuclear power stations or power stations, radioactive storage, natural gas or CO2, large dams and tunnels, hydroelectricity projects...) and the type of earthquake (single or multiple), the time period for evaluating active tectonics varies between 10,000 and 100,000 years for studies prior to beginning construction work.
The study, which is now published in the magazine Geomorphology and is the result of the doctoral thesis of Rachid El Hamdouni, Professor of the Departament of Civil Engineering at the University of Granada, defines a new geomorphological index called Relative Active Tectonics Indexpos, which identifies four classes of active tectonics (from low to very high) and uses six geomorphological indicators.
“The main use of this new index is that it establishes a close relationship between this, the land forms, and direct evidence of active faults”, El Hamdouni explained.
A seismic map for southern Spain
The indices are calculated with the help of Geographical Information Systems and teledetection programs in large areas which identify geomorphological anomalies possibly related to active tectonics. “This is really useful in southern Spain where studies on active tectonics are not very widely distributed”, Chacón pointed out.
The study has focused on the Padul-Dúrcal fault and a series of associated fault structures on the edge of the Sierra Nevada, where over the last 30 years seismic activity has been recorded by the Observatory of the Andalusian Institute of Geophysics and Prevention of Seismic Disasters. Chacón explained that the map obtained with the new index depends exclusively on the land forms and divides the area studied into four parts, “of which two thirds of the total area is classed as having high or very high tectonic activity”.
The Sierra Nevada is an Alpine mountain chain “with variable active tectonic gradients caused by the collision of Africa with Europe which has given rise to anticlines aligned from east to west, as well as the transverse extension with variable vertical gradients around 0.5 mm/year in normal faults”, Chacón specified.
http://www.sciencedaily.com/releases/2008/09/080911142421.htm
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"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."
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Big Bunny
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| | Re: Earthquakes II
« Reply #1 on Sept 17, 2008, 8:04am » | |
Earth Structure: Lowermost Mantle Has Materials With Unexpected Properties
ScienceDaily (Sep. 17, 2008) — Materials deep inside Earth have unexpected atomic properties that might force earth scientists to revise their models of Earth’s internal processes, a team of researchers has discovered.
The researchers recreated in the lab the materials, crushing pressures and infernal temperatures they believe exist in the lowermost mantle, nearly 2,900 kilometers (1,800 miles) below Earth’s surface. They report in the journal Nature Geoscience the materials exhibit rare and unexpected atomic properties that might influence how heat is transferred within Earth’s mantle, how columns of hot rock called superplumes form, and how the magnetic field and heat generated in Earth’s core travel to the planet’s surface.
The planetary building blocks magnesium, silicon, oxygen and iron are the most abundant minerals in the lowermost mantle. A team of scientists led by Jung-Fu Lin at The University of Texas at Austin’s Jackson School of Geosciences synthesized materials from these building blocks in a diamond anvil cell, a device containing two interlocking diamond pieces that squeeze the sample like a vice. They subjected the sample to more than 1.3 million times standard atmospheric pressure. Shining a laser through the transparent diamonds, they then heated the sample to almost 3,000 degrees Celsius (5,400 degrees Fahrenheit) for several days.
The scientists used the nation’s most powerful source of X-rays, a facility at Argonne National Laboratory called a synchrotron light source, to reveal the sample’s electronic and atomic structure. They determined the high pressures had caused some of the electrons in the sample’s iron, which normally repel each other, to “pair up” or become bound to each other. Earlier experiments by Lin and others had found evidence for areas in the lower mantle in which electrons were either mostly paired up or were mostly unpaired. This was the first evidence of a broad region in the subsurface with what scientists describe as “intermediate-spin state,” or partially paired iron electrons.
“We were surprised to find partially paired electrons,” said Lin. “That doesn’t normally occur in other geological materials that we know about.”
The degree of electron pairing, also known as electronic spin state, can affect how well the materials conduct heat and electricity. Lin said modelers who make computer simulations of mantle dynamics will now have to go back and try to determine how this intermediate-spin state might affect the way heat is transferred within Earth, how superplumes form, how convection occurs in the mantle and how Earth’s magnetic field might radiate from the core.
The electronic spin state can also affect the speed of seismic waves traveling through material in the deep mantle. As a result, seismic images of the lowermost mantle—collected when earthquake vibrations travel through and reflect off of material in the subsurface—may have to be reinterpreted.
Lin’s co-authors include Heather Watson and William J. Evans at Lawrence Livermore National Laboratory; György Vankó at KFKI Research Institute for Particle and Nuclear Physics in Budapest, Hungary; Esen E. Alp and Jiyong Zhao at Argonne National Laboratory; Vitali B. Prakapenka, Przemek Dera and Atsushi Kubo at the University of Chicago; Viktor V. Struzhkin at Carnegie Institution of Washington; and Catherine McCammon at Universität Bayreuth in Germany.
Journal reference:
1. Lin et al. Intermediate-spin ferrous iron in lowermost mantle post-perovskite and perovskite. Nature Geoscience, October 2008 edition and online Sept. 14,2008 DOI: 10.1038/ngeo310
http://www.sciencedaily.com/releases/2008/09/080916105720.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 #2 on Sept 24, 2008, 6:21am » | |
Latest significant seismic activity:
DATE LAT LON MAG DEPTH REGION
24-SEP-2008 02:33:11 17.83 -105.49 6.4 41.7 OFF COAST OF JALISCO, MEXICO
23-SEP-2008 22:46:23 16.86 -99.83 4.9 45.7 NEAR COAST OF GUERRERO, MEXICO
22-SEP-2008 15:44:11 8.40 -103.56 4.5 10.0 NORTHERN EAST PACIFIC RISE
22-SEP-2008 05:55:58 16.89 -99.79 4.6 42.5 NEAR COAST OF GUERRERO, MEXICO
21-SEP-2008 16:50:55 8.85 -102.86 4.6 10.0 NORTHERN EAST PACIFIC RISE
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 #3 on Sept 25, 2008, 6:30am » | |
Boulders on Tonga may have been dumped by tsunami
Posted 2008/09/24 at 6:39 pm EDT
WASHINGTON, Sep. 24, 2008 (Reuters) — Seven monstrous chunks of coral lined up on the western shore of Tonga may be evidence of a powerful volcano-triggered tsunami, researchers said on Wednesday.
The house-sized boulders, some as high as 30 feet high and weighing up to 3.5 million pounds (1.6 million kg), appear to have been carried ashore several thousand years ago by a wave rivaling the tsunami generated by Indonesia's Krakatoa volcano in 1883.
"These could be the largest boulders displaced by a tsunami, worldwide," Matthew Hornbach of the University of Texas Institute for Geophysics said in a statement.
Hornbach, whose team is preparing a report on the boulders for a meeting of the Geological Society of America in Houston next month, said they are so unusual that tales of their origins appear in Tongan folklore.
According to one legend, the god Maui hurled the boulders ashore in an attempt to kill a giant human-eating fowl.
"We think studying erratic boulders is one way of getting better statistics on mega-tsunamis," Hornbach said. "There are a lot of places that have similar underwater volcanoes and people haven't paid much attention to the threat."
http://www.newsdaily.com/stories/tre48n92v-us-tsunami-boulders-science/
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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 #4 on Sept 25, 2008, 9:35am » | |
Stalagmites May Predict Next Big One Along The New Madrid Seismic Zone
![[image]](http://img529.imageshack.us/img529/1086/080924185742large278138sz5.jpg "[image]")
Small white stalagmites. Insert: one stalagmite cut vertically in half, showing generations of growth with the white one on top. (Credit: Courtesy of K. Hackley)
ScienceDaily (Sep. 24, 2008) — Small white stalagmites lining caves in the Midwest may help scientists chronicle the history of the New Madrid Seismic Zone (NMSZ) – and even predict when the next big earthquake may strike, say researchers at the Illinois State Geological Survey and the University of Illinois at Urbana-Champaign.
While the 1811-12, magnitude 8 New Madrid earthquake altered the course of the Mississippi River and rung church bells in major cities along the East Coast, records of the seismic zone’s previous movements are scarce. Thick layers of sediment have buried the trace of the NMSZ and scientists must search for rare sand blows and liquefaction features, small mounds of liquefied sand that squirt to the surface through fractures during earthquakes, to record past events. That’s where the stalagmites come in.
The sand blows are few and far between, said Keith Hackley, an isotope geochemist with the Illinois State Geological Survey. In contrast, caves throughout the region are lined with abundant stalagmites, which could provide a better record of past quakes. “We’re trying to see if the initiation of these stalagmites might be fault-induced, recording very large earthquakes that have occurred along the NMSZ,” he said.
Hackley and co-workers used U-Th dating techniques to determine the age of stalagmites from Illinois Caverns and Fogelpole Cave in southwestern Illinois. They discovered that some of the young stalagmites began to form at the time of the 1811-12 earthquake.
Hackley is scheduled to present preliminary results of the study in a poster at the 2008 Joint Meeting of the Geological Society of America (GSA), Soil Science Society of America (SSSA), American Society of Agronomy (ASA), Crop Science Society of America (CSSA), and Gulf Coast Association of Geological Societies (GCAGS), in Houston, Texas, USA.*
Water slowly trickles through crevices in the ceiling of a cave and drips onto the floor. Each calcium carbonate-loaded drip falls on the last, and a stalagmite slowly grows from the bottom up. Time is typically recorded in alternating light and dark layers – each pair represents a year.
When a large earthquake shakes the ground, old cracks may seal and new ones open. As a result, some groundwater seeping through the cave ceiling traces a new pattern of drips – and, eventually, stalagmites – on the cave floor. Thus it is possible that each new generation of stalagmites records the latest earthquake.
The scientists use fine drills, much like those used by dentists, to burrow into the stalagmites to collect material for dating. In addition to the 1811-12 earthquake, their investigation has recorded seven historic earthquakes dating as far back as almost 18,000 years before the present. Understanding the NMSZ’s past, including whether quakes recur with any regularity, will help the scientists predict the potential timing of future quakes.
In coming months, Hackley and his colleagues plan to expand the study, collecting stalagmites from caves across Indiana, Missouri and Kentucky. They hope that the new data will help to fill in more of the missing history of the NMSZ.
*On 5 October the Paper 147-8: “Paleo-Seismic Activity from the New Madrid Seismic Zone Recorded in Stalagmites. A New Tool for Paleo-Seismic History”will be presented at the Joint Meeting.
http://www.sciencedaily.com/releases/2008/09/080924185742.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 #5 on Sept 25, 2008, 9:51am » | |
World’s Largest Tsunami Debris Discovered
![[image]](http://img220.imageshack.us/img220/4018/080924185324large374048ix0.jpg "[image]")
Tongatapu boulder. (Credit: Courtesy of M. Hornbach)
ScienceDaily (Sep. 25, 2008) — A line of massive boulders on the western shore of Tonga may be evidence of the most powerful volcano-triggered tsunami found to date. Up to 9 meters (30 feet) high and weighing up to 1.6 million kilograms (3.5 million pounds), the seven coral boulders are located 100 to 400 meters (300 to 1,300 feet) from the coast.
The house-sized boulders were likely flung ashore by a wave rivaling the 1883 Krakatau tsunami, which is estimated to have towered 35 meters (115 feet) high.
“These could be the largest boulders displaced by a tsunami, worldwide,” says Matthew Hornbach of the University of Texas Institute for Geophysics. “Krakatau’s tsunami was probably not a one-off event.” Hornbach and his colleagues will discuss these findings at the Joint Annual Meeting of the Geological Society of America (GSA), Soil Science Society of America (SSSA), American Society of Agronomy (ASA), Crop Science Society of America (CSSA), and the Gulf Coast Association of Geological Societies (GCAGS), in Houston, Texas, USA.*
Called erratic boulders, these giant coral rocks did not form at their present location on Tongatapu, Tonga’s main island. Because the island is flat, the boulders could not have rolled downhill from elsewhere. The boulders are made of the same reef material found just offshore, which is quite distinct from the island’s volcanic soil. In fact, satellite photos show a clear break in the reef opposite one of the biggest boulders. And some of the boulders’ coral animals are oriented upside down or sideways instead of toward the sun, as they are on the reef.
Hornbach says the Tongatapu boulders may have reached dry land within the past few thousand years. Though their corals formed roughly 122,000 years ago, they are capped by a sparse layer of soil. And the thick volcanic soils that cover most of western Tongatapu are quite thin near the boulders. This suggests the area was scoured clean by waves in the recent past. Finally, there is no limestone pedestal at the base of the boulders, which should have formed as rain dissolved the coral if the boulders were much older.
Many tsunamis, like the one that struck the Indian Ocean in 2004, are caused by earthquakes. But the boulders’ location makes an underwater eruption or submarine slide a more likely culprit. A chain of sunken volcanoes lies just 30 kilometers (20 miles) west of Tongatapu. An explosion or the collapse of the side of a volcano such as that seen at the famous Krakatau eruption in 1883 could trigger a tremendous tsunami.
Another possibility is that a storm surge could have brought the boulders ashore. But that scenario isn’t likely. No storms on record have moved rocks this big. Another possibility is that a monster undersea landslide caused the tsunami. But Hornbach’s analyses of adjacent seafloor topography point to a volcanic flank collapse as the most probable source of such a wave.
“We think studying erratic boulders is one way of getting better statistics on mega-tsunamis,” Hornbach says. “There are a lot of places that have similar underwater volcanoes and people haven’t paid much attention to the threat.” The researchers have already received reports of more erratic boulders from islands around the Pacific. Future study could indicate how frequently these monster waves occur and which areas are at risk for future tsunamis.
The boulders are such an unusual part of the Tongan landscape that tales of their origins appear in local folklore. According to one legend, the god Maui hurled the boulders ashore in an attempt to kill a giant man-eating fowl.
And though many other Pacific islanders follow the custom of heading uphill after earthquakes, Tongans have no such teachings. Such lore may be useless for near-shore volcanically-generated tsunamis, which arrive too quickly for people to evacuate. Instead, most of Tongatapu’s settlements are huddled together on the northern side of the island—away from the brunt of the tsunami threat.
*The abstract “Unraveling the Source of Large Erratic Boulders on Tonga: Implications for Geohazards and Mega-Tsunamis” will be presented on 5 October 2008.
http://www.sciencedaily.com/releases/2008/09/080924185324.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 #6 on Sept 27, 2008, 12:05am » | |
Latest significant seismic activity:
DATE LAT LON MAG DEPTH REGION
27-SEP-2008 03:09:13 13.40 120.48 6.1 77.1 MINDORO, PHILIPPINE ISLANDS
27-SEP-2008 03:05:00 13.39 120.49 5.6 82.0 MINDORO, PHILIPPINE ISLANDS
13-SEP-2008 02:52:43 7.69 123.90 4.5 599.0 MINDANAO, PHILIPPINE 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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tenger
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| | Re: Earthquakes II
« Reply #7 on Sept 29, 2008, 8:03pm » | |
http://earthquake.usgs.gov/eqcenter/recenteqsww/Quakes/us2008xna6.php
Magnitude 7.0
Date-Time Monday, September 29, 2008 at 15:19:31 UTC
Tuesday, September 30, 2008 at 03:19:31 AM at epicenter
Time of Earthquake in other Time Zones
Location 29.872°S, 177.684°W
Depth 35 km (21.7 miles) set by location program
Region KERMADEC ISLANDS, NEW ZEALAND
Distances 70 km (45 miles) SSE of Raoul Island, Kermadec Islands
210 km (130 miles) NE of L'Esperance Rock, Kermadec Islands
1050 km (650 miles) NE of Auckland, New Zealand
1440 km (890 miles) NNE of WELLINGTON, New Zealand
Location Uncertainty horizontal +/- 6.8 km (4.2 miles); depth fixed by location program
Parameters NST=295, Nph=295, Dmin=>999 km, Rmss=1.04 sec, Gp= 32°,
M-type=regional moment magnitude (Mw), Version=Q
Source USGS NEIC (WDCS-D)
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Big Bunny
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| | Re: Earthquakes II
« Reply #8 on Oct 5, 2008, 1:31pm » | |
Thanks, Tenger - in other seismic activity today:
DATE LAT LON MAG DEPTH REGION
05-OCT-2008 22:56:33 33.95 69.48 6.0 35.0 AFGHANISTAN
05-OCT-2008 18:27:41 39.53 73.87 5.1 35.0 TAJIKISTAN-XINJIANG BORDER REG.
05-OCT-2008 17:33:54 39.63 73.83 4.2 35.0 TAJIKISTAN-XINJIANG BORDER REG.
05-OCT-2008 17:12:36 39.22 73.61 4.0 35.0 TAJIKISTAN-XINJIANG BORDER REG.
05-OCT-2008 17:00:30 39.51 73.70 4.1 35.0 TAJIKISTAN-XINJIANG BORDER REG.
05-OCT-2008 16:52:57 39.56 73.77 4.7 35.0 TAJIKISTAN-XINJIANG BORDER REG.
05-OCT-2008 16:51:42 39.33 73.82 4.5 35.0 TAJIKISTAN-XINJIANG BORDER REG.
05-OCT-2008 16:11:11 39.52 73.88 5.7 35.0 TAJIKISTAN-XINJIANG BORDER REG.
05-OCT-2008 15:52:50 39.54 73.77 6.3 35.0 TAJIKISTAN-XINJIANG BORDER REG.
http://www.iris.edu/seismon/
Further:
Deadly earthquake hits Kyrgyzstan
A major earthquake has hit Kyrgyzstan, killing at least 65 people, officials in the Central Asian nation say.
![[image]](http://img412.imageshack.us/img412/3796/45081003kyrgyzosh090814ue9.gif "[image]") ![[image]](http://img511.imageshack.us/img511/5221/4508348853d68f9cbe6842bar3.jpg "[image]")
The 6.6-magnitude quake struck at 2152 local time (1552 GMT) on Sunday, destroying more than 100 buildings in the southern province of Osh.
Rescue workers are still searching for survivors under the rubble, the emergencies ministry said.
Destruction was concentrated in Nura, a village in the mountains close to the border with China.
Health officials said the remote location of the village was hampering rescue efforts.
"The picture we saw was frightening," Emergency Situations Minister Kamchybek Tashiyev was quoted as saying by AFP news agency.
"The village of Nura is fully destroyed, 100%, there are many injured."
Russian condolences
People throughout Central Asia felt the quake.
The US geological survey said its epicentre was in Tajikistan and initially estimated its magnitude at 6.3 - although it later revised that to 6.6.
Officials in China's Xinjiang province reported minor damage to houses, but so far no casualties have been reported there.
In Kyrgyzstan, emergency ministry spokesman Abdusamat Payazov said many areas of the country had experienced the tremor.
"In Osh the quake was registered at 6 in magnitude, in Batken region 5 to 6, and in Bishkek up to 3.5," he told the BBC.
Russian President Dmitry Medvedev, due to visit Kyrgyzstan later this week, sent his condolences in a telegram.
He said that he was ready to provide humanitarian assistance.
Kyrgyzstan is a landlocked nation of five million people.
About 90% of the country is mountainous, and seismological events are common.
Over the past two years there have been two large earthquakes in Osh and Naryn areas.
Story from BBC NEWS:
http://news.bbc.co.uk/go/pr/fr/-/2/hi/asia-pacific/7653979.stm
Published: 2008/10/06 11:33:33 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 #9 on Oct 5, 2008, 8:59pm » | |
How Many Earthquakes Are There?
ScienceDaily (Oct. 2, 2008) — A new method for estimating the capability of a network to detect earthquakes suggests that the seismic monitoring network for Southern California, as an example, does not accurately reflect all earthquakes that register a magnitude of 3.3 or smaller within southern California, thereby giving seismologists an incomplete picture of recent and current seismicity.
The study, published in the October issue of the Bulletin of the Seismological Society of America, provides a new empirically-based approach for seismologists to understand the detection capabilities of seismic networks.
While today's improved seismic networks detect earthquakes down to low magnitudes in regions of the densest coverage, seismologists need to estimate the completeness magnitude which varies in space and time. This magnitude of completeness indicates the magnitude below which the earthquake catalog does not contain all events that occurred..
D. Schorlemmer of the University of Southern California (USC) and J. Woessner of the Swiss Seismological Service present a new approach to estimate the magnitude of completeness which will enable scientists to develop a richer understanding of the distribution of smaller earthquakes. The authors' new approach uses an analysis based on the actual performance of seismic stations rather than a theoretical assessment based on sampling of earthquakes.
This advancement is important because one way scientists estimate the number of large, damaging earthquakes is to study the distribution of small earthquakes. Without an accurate understanding of how likely the seismic networks are detecting earthquakes of different magnitudes, scientists may obtain incorrect seismic hazard estimates for an area.
http://www.sciencedaily.com/releases/2008/10/081003081641.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 #10 on Oct 6, 2008, 2:07pm » | |
Latest significant seismic activity:
DATE LAT LON MAG DEPTH REGION
06-OCT-2008 12:10:33 29.60 90.28 5.4 10.0 XIZANG
06-OCT-2008 10:17:11 29.72 90.33 4.9 10.0 XIZANG
06-OCT-2008 08:45:07 29.78 90.18 5.1 10.0 XIZANG
06-OCT-2008 08:30:45 29.76 90.30 6.6 10.0 XIZANG
http://www.iris.edu/seismon/
Further:
Tibetan earthquakes kill dozens
Two quakes which struck the Himalayan region of Tibet have killed at least 30 people, Chinese state media report.
![[image]](http://img505.imageshack.us/img505/2135/4508296965ed928110f64e9mt2.gif "[image]")
The earthquakes struck about 16km (10 miles) and 15 minutes apart in a sparsely populated area about 84km (50 miles) west of Tibet's capital, Lhasa.
The US Geological Survey said the magnitude of the first quake was 6.6 and that of the second - 5.1.
Many houses collapsed near the epicentre in Damxung county, China's Xinhua news agency says.
Buildings shaken
The area has a population of about 42,000 people, mostly herdsmen.
The director of the Tibetan seismological department, Zhu Quan, says the authorities are still trying to determine the exact number of casualties.
Local officials in Damxung county said more people were still buried under debris.
The earthquake shook buildings in Lhasa, prompting office workers to rush out of their buildings into the street.
However, there have been no reported casualties in the city and damage to buildings is minimal.
Shops remain open and train and air links have not been affected.
The tremors in Tibet - at about 1630 (0830 GMT) - came after a 6.6 magnitude earthquake struck neighbouring Kyrgyzstan, near its border with China, killing at least 65 people.
Story from BBC NEWS:
http://news.bbc.co.uk/go/pr/fr/-/2/hi/asia-pacific/7655032.stm
Published: 2008/10/06 14:29:25 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 #11 on Oct 6, 2008, 2:10pm » | |
Latest significant seismic activity:
DATE LAT LON MAG DEPTH REGION
06-OCT-2008 07:50:33 39.64 73.69 4.6 35.0 TAJIKISTAN-XINJIANG BORDER REG.
05-OCT-2008 22:56:33 33.95 69.48 6.0 35.0 AFGHANISTAN
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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Posts: 50,820
Location: Sydney, Australia
| | Re: Earthquakes II
« Reply #12 on Oct 7, 2008, 1:04am » | |
Indonesian volcano spews lava
From correspondents in Jakarta
October 07, 2008 04:42pm
INDONESIA has raised the alert level for a volcano on Sulawesi island after it began spewing hot clouds and lava.
![[image]](http://img257.imageshack.us/img257/6646/06288176009272264av7.jpg "[image]")
Lava from Soputan volcano flowed up to 1km from the crater while white clouds and fiery sparks shot up about 150 metres from the peak, said Surono, the head of the vulcanology centre.
He said the status was raised to the second highest level yesterday and campers had been told to stay away from the volcano, but people living on the slopes are not being evacuated as the lava will not reach that far.
Indonesia has the highest number of active volcanoes of any country, sitting on a belt of intense volcanic and seismic activity known as the "Pacific Ring of Fire".
People often live and farm on the slopes of volcanoes because of the rich volcanic soil.
In the past two years, at least three major volcanoes, including Anak Krakatau, have showed signs of increased activity, but there has been no serious eruption.
http://www.news.com.au/story/0,23599,24460734-23109,00.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
Admin
member is offline
Joined: Apr 2003
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Posts: 50,820
Location: Sydney, Australia
| | Re: Earthquakes II
« Reply #13 on Oct 7, 2008, 10:34am » | |
Latest VERY significant seismic activity:
DATE LAT LON MAG DEPTH REGION
08-OCT-2008 07:57:34 79.82 -115.41 5.3 10.0 ARCTIC OCEAN
07-OCT-2008 19:49:04 79.69 -115.16 4.4 10.0 ARCTIC OCEAN
07-OCT-2008 10:00:48 79.83 -115.23 5.8 10.0 ARCTIC OCEAN
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
Gender: Male
Posts: 50,820
Location: Sydney, Australia
| | Re: Earthquakes II
« Reply #14 on Oct 10, 2008, 5:36am » | |
Deep Magma Matters: Volcanic Eruptions More Complex And Harder To Predict
![[image]](http://img516.imageshack.us/img516/9084/081009144101large485804uv5.jpg "[image]")
Pyroclastic flow across old city of Plymouth from the Soufrière Hills volcano on the island of Montserrat in the Caribbean. (Credit: iStockphoto/Sean Hannah)
ScienceDaily (Oct. 9, 2008) — New research by a team of US and UK scientists into volcanoes has found that they function in a far more complex way than previously thought, making future eruptions even harder to predict.
Although the Soufrière Hills volcano on the Caribbean island of Montserrat exhibits cycles of eruption and quiet, the international team of researchers found that magma is continuously supplied from deep in the crust but that a valve acts below a shallower magma chamber, releasing lava to the surface periodically.
"Continuous records of surface deformation are available for only a few volcanoes," says Derek Elsworth, professor of energy and geo-environmental engineering, Penn State. "The Soufrière Hills volcano has been erupting since 1995 and provides a peek into the processes occurring deep beneath this stratovolcano."
Stratovolcanoes are one of the most common forms of volcano on Earth. They are cone-shaped with steep sides created by episodic eruptions of magma that flow down from the cone a short way and create layer upon layer of volcanic material.
The researchers, who include Elsworth; Barry Voight, professor emeritus of geology and geological engineering, and Joshua Taron, a doctoral student in energy and geo-environmental engineering, Penn State; Glen Mattioli, professor of geosciences, University of Arkansas, and Richard Herd, senior lecturer in geophysical Earth observation, University of East Anglia, UK, report on using measurements of ground inflation and deflation as a window to the transfer of magma deep within the crust. From these observations, "it is apparent that the major changes in magma storage that have supplied the eruption are from depth, with the lower reservoir contributing only a third of the erupted volume," they say in the journal Science.
In 1995, the Soufrière Hills volcano began the current series of eruptions and pauses. The November 1995 event lasted until March 1998, during which time a dome of andesite – a volcanic rock – grew continuously. From March 1998 until November 1999, there was a pause in above ground volcanic activity and the lava dome collapsed from its own weight and inactivity. Beginning in December 1999, the second episode continued until mid-July 2003, followed by a pause until October 2005. The third episode began then and ended in March 2007.
"The pause that began in 2007 apparently ended in August 2008 with the slow extrusion of lava on the western flank of the dome," says Elsworth.
The pattern of eruptions and pauses might suggest that the magma beneath the Earth behaves in a stop-and-start pattern but the data indicate that magma production beneath the volcano is continuous and relatively constant. During eruptive pauses, the magma supply inflates the deep chamber until this stored magma is released into the upper chamber where it forces a renewed eruption. These observations implicate the deep reservoir in setting the timing of eruptions, rather than the shallow chamber, as had previously been considered.
The researchers believe that the upper reservoir is open and that there is a "valve" between it and the lower reservoir because the lower reservoir can refill while the upper reservoir is open and unaffected. It is unknown whether a build-up of heat or the pressure of gas breaches the valve from the lower to upper reservoir.
Analysis of the data collected on the Soufrière Hills volcano also indicates that the periodic eruptions deplete only the lower magma reservoir, not the upper reservoir. During lulls in eruption, the deep reservoir refills but at only half the rate that the magma was lost. Because the pauses between eruptions are shorter than the eruptions, the deep magma chamber does not make up the pre-eruption volume and the deep magma chamber, over time, contains less and less magma.
The National Science Foundation supported this work.
Journal reference:
1. Derek Elsworth, Joshua Taron and Barry Voight (all Penn State University), Richard Herd (University of East Anglia) and Glen Mattioli (University of Arkansas). Implications of Magma Transfer Between Multiple Reservoirs on Eruption Cycling. Science, October 10, 2008
http://www.sciencedaily.com/releases/2008/10/081009144101.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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