Earth Watch Report – Saturday August 25th, 2012
August 25, 2012 by desertrose
Earthquakes
RSOE EDIS
| Date/Time (UTC) | Magnitude | Area | Country | State/Prov./Gov. | Location | Risk | Source | Details | ||
| 25.08.2012 10:45:36 | 2.9 | North America | United States | California | Cobb |  |
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USGS-RSOE |  |
| 25.08.2012 10:50:23 | 2.3 | Europe | Italy | Calabria | Salerni | |
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EMSC | |
| 25.08.2012 10:35:34 | 2.1 | North America | United States | Alaska | Sterling | |
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USGS-RSOE | |
| 25.08.2012 10:50:47 | 2.4 | Europe | Italy | Calabria | Salerni | |
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EMSC | |
| 25.08.2012 10:40:33 | 3.4 | Caribbean | British Virgin Islands | Road Town | |
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USGS-RSOE | |
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| 25.08.2012 09:50:19 | 4.1 | Asia | Turkey | Manisa | Golmarmara | |
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EMSC | |
| 25.08.2012 09:20:57 | 2.3 | North America | United States | California | Big Bear Lake | |
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USGS-RSOE | |
| 25.08.2012 10:00:30 | 4.0 | Caribbean | British Virgin Islands | Road Town | |
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USGS-RSOE | |
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| 25.08.2012 10:51:10 | 4.0 | Caribbean Sea | British Virgin Islands | Road Town | |
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EMSC | |
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| 25.08.2012 10:52:02 | 3.9 | Caribbean | British Virgin Islands | Road Town | |
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USGS-RSOE | |
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| 25.08.2012 08:52:29 | 2.3 | North America | United States | California | Saratoga | |
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USGS-RSOE | |
| 25.08.2012 08:30:56 | 2.8 | North America | United States | Utah | Big Water | |
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USGS-RSOE | |
| 25.08.2012 08:50:20 | 3.8 | Europe | Greece | Central Greece | Roviai | |
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EMSC | |
| 25.08.2012 08:50:51 | 2.9 | Europe | Greece | Crete | Kissamos | |
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EMSC | |
| 25.08.2012 08:51:34 | 2.4 | Europe | Bosnia and Herzegovina | Federation of Bosnia and Herzegovina | Vitez | |
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EMSC | |
| 25.08.2012 07:50:18 | 2.4 | Europe | Greece | North Aegean | Mithymna | |
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EMSC | |
| 25.08.2012 06:45:26 | 3.1 | South-America | Chile | Región Metropolitana | La Pintana | |
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EMSC | |
| 25.08.2012 05:55:33 | 2.8 | North America | United States | California | Avalon | |
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USGS-RSOE | |
| 25.08.2012 07:50:43 | 2.3 | Asia | Turkey | Amasya | Dedekoy | |
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EMSC | |
| 25.08.2012 07:51:04 | 3.8 | Europe | Russia | Tyva | Sukpak | |
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EMSC | |
| 25.08.2012 07:51:25 | 2.6 | Asia | Turkey | Antalya | Kalkan | |
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EMSC | |
| 25.08.2012 05:50:28 | 4.4 | Pacific Ocean – West | Vanuatu | Torba | Sola | |
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USGS-RSOE | |
| 25.08.2012 06:45:45 | 4.4 | Pacific Ocean – West | Vanuatu | Torba | Sola | |
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EMSC | |
| 25.08.2012 06:46:03 | 2.8 | Asia | Turkey | Amasya | Dedekoy | |
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EMSC | |
| 25.08.2012 05:40:37 | 2.8 | Asia | Turkey | Amasya | Dedekoy | |
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EMSC | |
| 25.08.2012 06:46:22 | 2.2 | Asia | Turkey | Amasya | Dedekoy | |
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EMSC | |
| 25.08.2012 04:56:05 | 2.5 | North America | United States | California | Indianola | |
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USGS-RSOE | |
| 25.08.2012 05:41:44 | 3.1 | Europe | Greece | Crete | Yialos | |
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EMSC | |
| 25.08.2012 04:40:50 | 2.3 | North America | United States | Alaska | Petersville | |
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USGS-RSOE | |
| 25.08.2012 04:40:21 | 2.5 | Europe | Italy | Sicily | Saponara Villafranca | |
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EMSC | |
| 25.08.2012 03:40:20 | 2.7 | Europe | Romania | Mehedin?i | Svinita | |
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EMSC | |
| 25.08.2012 03:40:44 | 3.5 | Europe | Greece | Peloponnese | Elafonisos | |
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EMSC | |
| 25.08.2012 02:45:55 | 3.1 | Caribbean | U.S. Virgin Islands | Saint Thomas Island | Charlotte Amalie | |
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USGS-RSOE | |
| 25.08.2012 03:41:10 | 4.1 | Africa | Algeria | Chlef | Sidi Akkacha | |
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EMSC | |
| 25.08.2012 01:16:21 | 2.1 | North America | United States | California | Big Bear City | |
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USGS-RSOE | |
| 25.08.2012 06:16:00 | 2.2 | North America | United States | Oregon | Paisley | |
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USGS-RSOE | |
| 25.08.2012 01:40:18 | 4.6 | Indonesian Archipelago | Indonesia | Bengkulu | Curup | |
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EMSC | |
| 25.08.2012 01:41:38 | 4.7 | Indonesian archipelago | Indonesia | Bengkulu | Curup | |
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USGS-RSOE | |
| 25.08.2012 01:40:46 | 2.4 | Europe | Italy | Calabria | Nicastro | |
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EMSC | |
| 25.08.2012 01:41:11 | 4.4 | South-America | Chile | Valparaíso | San Antonio | |
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EMSC | |
| 25.08.2012 00:50:57 | 4.7 | South America | Chile | Valparaíso | San Antonio | |
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USGS-RSOE | |
| 25.08.2012 00:35:26 | 2.4 | Europe | Italy | Abruzzo | Balsorano Vecchio | |
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EMSC | |
| 25.08.2012 00:35:51 | 3.0 | Europe | Greece | North Aegean | Agia Paraskevi | |
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EMSC | |
| 25.08.2012 00:36:13 | 2.0 | Europe | Italy | Lombardy | Ospitaletto | |
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EMSC | |
| 25.08.2012 00:05:27 | 3.9 | North America | United States | Alaska | Healy | |
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USGS-RSOE | |
| 25.08.2012 00:36:34 | 4.7 | Indonesian Archipelago | Indonesia | Aceh | Meulaboh | |
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EMSC | |
| 25.08.2012 00:10:26 | 4.7 | Indonesian archipelago | Indonesia | Aceh | Meulaboh | |
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USGS-RSOE | |
| 25.08.2012 00:36:55 | 2.6 | Europe | Italy | Emilia-Romagna | San Prospero | |
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EMSC | |
| 25.08.2012 06:46:42 | 2.0 | Asia | Turkey | Van | Toyga | |
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EMSC | |
| 25.08.2012 00:37:17 | 2.7 | Asia | Turkey | Afyonkarahisar | Kiziloren | |
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EMSC | |
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Four quakes rock Nepal in past 12 hours
National Seismological Centre has its stations across the country.
KESHAV P. KOIRALA
KATHMANDU: Four consecutive earthquakes — two of them powerful ones — rocked western Nepal in past 12 hours.
With their epicentres in the border area of Rolpa and Rukum districts, the tremors of the first quake were felt in Kathmandu at 10:15 pm last night.
Its magnitude was 5.6 on the Richter Scale, according to Dilli Ram Tiwari, survey officer at National Seismological Centre (NSC) in Kathmandu.
The second quake was measured at 10:27 pm yesterday, and it was 4.4 in magnitude.
The NSC has recorded two earthquakes this morning also.
The quakes at 6:02 am and 9.40 am were 4.4 and 5.2 on the Richter Scale, Tiwari said.
It is yet to learn whether the quakes caused any damage in the areas near epicentre.
Courtesy: National Seismological Centre, Lainchaur
Antarctic Ice Sheet Quakes Shed Light On Ice Movement and Earthquakes
ScienceDaily
Analysis of small, repeating earthquakes in an Antarctic ice sheet may not only lead to an understanding of glacial movement, but may also shed light on stick slip earthquakes like those on the San Andreas fault or in Haiti, according to Penn State geoscientists.
“No one has ever seen anything with such regularity,” said Lucas K. Zoet, recent Penn State Ph. D. recipient, now a postdoctoral fellow at Iowa State University. “An earthquake every 25 minutes for a year.”
The researchers looked at seismic activity recorded during the Transantarctic Mountains Seismic Experiment from 2002 to 2003 on the David Glacier in Antarctica, coupled with data from the Global Seismic Network station Vanda. They found that the local earthquakes on the David Glacier, about 20,000 identified, were predominantly the same and occurred every 25 minutes give or take five minutes.
The researchers note in the current Nature Geoscience that, “The remarkable similarity of the waveforms … indicates that they share the same source location and source mechanisms.” They suggest that “the same subglacial asperity repeatedly ruptures in response to steady loading from the overlying ice, which is modulated by stress from the tide at the glacier front.”
“Our leading idea is that part of the bedrock is poking through the ductile till layer beneath the glacier,” said Zoet.
The researchers have determined that the asperity — or hill — is about a half mile in diameter.
The glacier, passing over the hill, creates a stick slip situation much like that on the San Andreas fault. The ice sticks on the hill and stress gradually builds until the energy behind the obstruction is high enough to move the ice forward. The ice moves in a step-by-step manner rather than smoothly.
But motion toward the sea is not the only thing acting on the ice streaming from David glacier. Like most glaciers near oceans, the edge of the ice floats out over the water and the floating ice is subject to the action of tides.
“When the tide comes in it pushes back on the ice, making the time between slips slightly longer,” said Sridhar Anandakrishnan, professor of geoscience. “When the tide goes out, the time between slips decreases.”
However, the researchers note that the tides are acting at the ground line, a long way from the location of the asperity and therefore the effects that shorten or lengthen the stick slip cycle are delayed.
“This was something we didn’t expect to see,” said Richard B. Alley, Evan Pugh Professor of Geosciences. “Seeing it is making us reevaluate the basics.”
He also noted that these glacial earthquakes, besides helping glaciologists understand the way ice moves, can provide a simple model for the stick slip earthquakes that occur between landmasses.
“We have not completely explained how ice sheets flow unless we can reproduce this effect,” said Alley. “We can use this as a probe and look into the physics so we better understand how glaciers move.”
Before 2002, this area of the David glacier flowed smoothly, but then for nearly a year the 20-minute earthquake intervals occurred and then stopped. Something occurred at the base of the ice to start and then stop these earthquakes.
“The best idea we have is that during those 300 days, a dirty patch of ice was in contact with the mount, changing the way stress was transferred,” said Zoet. “The glacier is experiencing earthquakes again, although at a different rate. It would be nice to study that.”
Unfortunately, the seismographic instruments that were on the glacier in 2002 no longer exist, and information is coming from only one source at the moment.
Tectonic Shoving Match Formed Caribbean Island Arc
OurAmazingPlanet Staff
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| The image shows how the Caribbean plate is pushed to the east relative to the South American plate, causing the Caribbean Islands’ distinctive arc shape. CREDIT: Courtesy of Meghan Miller and Thorsten Becker |
The movement of Earth’s viscous mantle against South America has pushed the Caribbean islands east over the last 50 million years, according to a study published Monday (Aug. 20) in the journal Nature Geoscience.
The University of Southern California, in announcing the study, said the findings upend previous hypotheses of the seismic activity beneath the Caribbean Sea and provide an important new look at the unique tectonic interactions that are causing the Caribbean plate to tear away from South America.
The Caribbean plate is being pushed eastward due to a thick section of the South American plate called a “cratonic keel.” This section of crust is three times
Meanwhile, part of the South American plate is being pushed beneath the Caribbean plate, a process called subduction. Intense heat and pressure gradually force water-containing magma to rise into the Earth’s mantle and fuel the many active volcanoes in the region.
All of this pushing and pulling formed the distinctive arc shape of the Caribbean islands and has created a very complex system of faults between the two plates, in northern South America, according to the USC statement. The study mapped several of these strike-slip faults, which are similar to California’s San Andreas Fault.
Recent earthquakes in the area helped the two researchers develop an image of the Earth’s deep interior. The earthquake waves move slower or quicker depending on the temperature and composition of the rock.
“Studying the deep earth interior provides insights into how the Earth has evolved into its present form,” researcher Meghan S. Miller said in the statement.
For their study, the researchers used earthquake data to develop 176 computer models, USC said
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Volcanic Activity
Volcano activity of August 23-24, 2012 – Mt. Tongariro, Sotara, Shiveluch, Karymsky, Santiaguito, Fuego, Sakurajima, Batu Tara, Tungurahua, Kilauea and Nevado del Ruiz
By Richard Wilson and Armand Vervaeck
August , 2012 volcano activity
Mount Tongariro volcano (New Zealand) showed some seismicity earlier today (see seismogram below). The activity can only be seen in Oturere and West Tongariro seismograms (close to the Te Maari craters). Below also one of the rara clear view images of Mt. Tongariro with a strongly steaming vent. N report from GNS science about the seismicity however. The Park service has announced that the trekking trails at Mount Tongariro would be reopened. A 3 km hazard and risk zone will remain in place for some time and might be further reduced once new information of the gas and ash composition is known.
According to INGEOMINAS, the Observatorio Vulcanológico and Sismológico de Popayán reported that during 8-14 August seismic activity at Sotará increased. The seismic network recorded 110 magnitude 0.2-1.6 events mainly located in an area 0.1-5 km NE of the peak, at depths of 2-6 km. Inflation was detected in the NE area, coincident with the zone of increased seismicity. Web-camera views showed no morphological changes. The Alert Level was raised to III (Yellow; “changes in the behavior of volcanic activity”), or the second lowest level. (Smithsonian Institute)
KVERT reported moderate seismic activity from Karymsky during 10-20 August. Satellite imagery showed a weak thermal anomaly on the volcano during 10-13, 15, and 18-20 August. The Aviation Color Code remained at Orange.
KVERT reported that during 10-18 August weak seismic activity was detected at Shiveluch. Observers noted gas-and-steam activity during 15-17 August; weather conditions prevented observations of the volcano on the other days. Satellite imagery showed a thermal anomaly on the lava dome during 10, 12-13, and 18-19 August. Seismic activity increased to moderate levels and hot avalanches were observed during 19-20 August. The Aviation Color Code remained at Orange.
Insivumeh reports 2 moderate explosions at Santiaguito (Santa Maria), Guatemala. The other Guatemala volcano, Fuego sends a white plume approx. 50 meter in the air and grumbles every 1 to 3 minutes. See also seismograms from both volcanoes.
Activity observed by satellites
VAAC reports still the same volcanoes which can be dangerous for aviation ; Sakurajima, Batu Tara and a very active Tungurahua
SO2 satellite imagery shows SO2 clouds at the following volcanoes : Etna, Kilauea and Nevado del Ruiz. Clouds of a number of other volcanoes are not defined enough to be sure.
A smoking Nevado del Ruiz yesterday – image courtesy Ingeominas Colombia
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