Lubricating Rock Trigger Earthquakes

The marine geology researchers from the University of California found that lubricants rock had lubricate the movement of tectonic plates that cause earthquakes. Not only affects the earthquake, these materials are also involved in the phenomenon of volcanic explosions. The study is published in the journal Nature.

For decades scientists have debated the forces and circumstances that allow the planet's tectonic plates to slide across the earth's mantle. Studies have shown that dissolved water in mantle minerals results in a more ductile mantle that would facilitate tectonic plate motions, but for many years clear images and data required to confirm or deny this idea were lacking. (Picture from: http://www.terradaily.com/)

Lubricant rock is melted rock that is located in the Earth's mantle layer. The material is a liquid foundation that makes shifting tectonic plates horizontally. "It lies at the confluence of the plate makes this material is important in understanding the geological activity," said Kerry Key, researchers from the Scripps Institution of Oceanography at University of California.

The study was conducted as a team of experts to follow marine expedition across the Central American trench off the coast of Nicaragua in 2010. They mapped the sea floor and the layers beneath it using a new technique discovered by Scripps researchers.

The device consists of an electromagnetic wave catcher held on the seabed. The sensor is very sensitive to the instrument detect vibrations produced natural movement of the earth's crust and mantle. The data they collect is sent back to the research vessel Melville.

The orange colored area enclosed by a dashed line denotes a magma layer that scientists believe is facilitating the motion of the Cocos plate off Nicaragua. The blue areas represent the Cocos plate sliding across the mantle and eventually diving beneath the Central American continent, while the black dots signify earthquake locations. The discovery was made by analyzing data collected by an array of seafloor electromagnetic instruments, shown as inverted triangles. (Picture from: http://www.natureworldnews.com/)

Through wave catcher tool, researchers can look like a "see-through" to a depth of 25 kilometers below the seabed. At this depth, the researchers saw a thick layer of molten rock, which support the Cocos plate, place of establishment of the Central American mainland.

"What is rock melting-boggling," he said. Prior to this discovery, the researchers argue about the cause of the length of plate movement in the Earth's mantle. One theory put forward is the seepage of water into the mantle minerals can turn into clay. This is a pave layer of plate movement. Over the years, investigators never found evidence to confirm or undermine this theory.

According to Key, the researchers did not find the presence of water to soften the coat. Lubricants plate, he said, produced by melting of mantle that is tough and quite slippery, and causes a horizontal shift. *** [EKA | FROM VARIOUS SOURCES | UNIVERSITY OF CALIFORNIA | ANTON WILLIAM | KORAN TEMPO 4177]

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Indonesian Volcanoes known "grumpy"

Who does not know Mt. Merapi? Almost all over of the world know it, because the volcano's  virulence when erupted in 2010 ago. Many world's volcanology experts come to study character changes when this volcano will erupt.

Mt. Merapi is touted as the world's most active volcanoes. Since 1548, this mountain has erupted 68 times as much. (Picture from: http://www.republika.co.id/)

Or with Mt. Tambora on Sumbawa Island? The volcano eruptions in 1815 became the largest eruption in the world of all time. The eruption was heard as far as 2,600 km, and ash fell at least up to 300 km. Darkness visible as far as 600 km from the mountain summit for more than two days. Pyroclastic flows spread at least 20 km from the summit. The Tambora eruption got the scale of seven on Volcanic Explosivity Index (VEI), which means was four times more powerful than the Krakatoa eruption in 1883. An estimated 100 km3 of ppyroclastic trakiandesit out and created caldera measuring 6 to 7 km with depth of 600 to 700 m. Before the eruption, Mt. Tambora height approximately 4,300 m, and after the eruption, the mountain height was left as high as 2,851 m.

Illustration of the eruption of Mount Tambora in 1815. (Picture from: http://anehcuy.blogspot.com/)

Map depicting the coverage area of volcanic ash fall Mt. Tambora eruption in 1815. (Picture from: http://strukturawam.wordpress.com/)

Geologists from the Bandung Institute of Technology (Institut Teknologi Bandung / ITB), Budi Brahmantyo, saying that Indonesian volcanoes are known as the "grumpy" volcanoes because of the nature of the activity and the relatively large eruptions. Moreover, Indonesia is included in the Pacific ring of fire.

Mt. Krakatoa caused catastrophic explosion in 1883 had global repercussions and left only remnants which continue shown seismic activity until today. (Picture from: http://fajaryusufrock.blogspot.com/)

"The Indonesian volcanoes are 'fierce' because they have relatively viscous of magma. Especially Indonesia's typical stratovolcano. Means that it is composed of volcanic rock eruption of the type of eruption varies so as to produce a multi-layered arrangement of some rock types. So when they erupting that came out not only the lava material but also the rocks. The outside visual of stratovolcano, the form of mountain is large or giant cone, sometimes has irregular shape because eruption that happen several hundred times," said Budi Brahmantyo.

Mt. Soputan in Southeast Minahasa district, in North Sulawesi province, which remove ash and heat clouds on July 3, 2011. (Picture from: http://noenkcahyana.blogspot.com/)

According to Budi, the type of volcano in Indonesia is different from the volcano in the Hawaiian Islands where the volcano directly contact with the Earth's mantle as a source of lava. Therefore, when they erupted that comes out only the lava, no rocks or pyroclastic because the lava did not have time to freeze. "Almost all Indonesian volcanoes are stratovolcano. Rarely does Indonesian volcano that have type like Hawaiian volcano that directly connected to the Earth's mantle," he adds.

A time exposure on September 6, 2010 shows a plume of volcanic ash rising from the crater of Mt. Sinabung as seen from Tanah Karo district in North Sumatra province, some two hours before its eruption. (Picture from: http://www.theepochtimes.com/)

Meanwhile, based on the level of activity, the Indonesian volcanoes are divided into three types, namely A, B, and C-type. A-type Volcano is a volcano that recorded has erupted at least one times since 1600, and in Indonesia the A-type volcano there are 79. Meanwhile, B-type is the volcano after the year 1600 have not been recorded again has magmatic eruption, but it is still showing volcanic activity symptoms such as solfatara activity. In Indonesia there are 29 volcanoes with this type. And C-type is the volcano has the unknown eruption history, but there are still signs of past events such as solfatara field or fumarola at the weak level. In Indonesia there are 21 volcanoes with this type.

Mt. Semeru is one of the A-type volcano in Indonesia. (Picture from: http://indonesiantraveldestination.blogspot.com/)

In Java Island itself, the volcanoes that included in A-type are Mt. Gede, Salak, Tangkubanparahu, Papandayan, Galunggung, Guntur, Cereme, Slamet, Butak Petarangan, Dieng, Sundoro, Sumbing, Merapi, Merbabu, Kelud, Arjuno Welirang, Semeru, Bromo, Lamongan, Raung, and Kawah Ijen. 

Mt. Iyang Argopura is one of the B-type volcano in Indonesia. (Picture from: http://greatadventureindonesia.blogspot.com/)

And the B-type volcanoes are Mt. Pulosari, Karang, Patuha, Wayang Windu, Talagabodas, Ungaran, Lawu, Wilis, and Iyang Argapura. And the volcanoes on Java Island that included in C-type, namely Mt. Kiaraberes Gagak, Perbakti, Kawahmanuk, Kawah Kamojang and Kawah Karaha.

Mt. Perbakti is one of the C-type volcano in Indonesia. (Picture from: http://www.panoramio.com/)

"Like Mt. Sinabung, before it included in the classification as B-type volcano because it never recorded erupted since 1600. However, when erupted in 2010, then Sinabung classified as A-type volcano," said Budi explained.

The Volcanoes in the World

Overall, an active volcano in the world amount 500 to 600. The volcanoes are mostly found on the mainland, which is about 83 percent, while the rest are spread as underwater volcanoes or called submarine volcano.

Inside of the ring of fire zone which are shaped like horseshoe and covers an area of ​​40,000 km2 along from New Zealand, Indonesia, to Chile, in South America, there were 550 active volcanoes.

Pacific Ring of Fire. (Picture from: http://membacafirst.wordpress.com/)

Approximately 62 percent of the world volcano is located in the Pacific Ocean where 45 percent of the Pacific islands scattered in the West and 17 percent in the suburbs of the North Pacific and the South Pacific. Indonesia itself "contributed" 14 percent of the world's volcanoes to form a line extending along the mountains current 7,000 to 7,500 km and a width of 50 to 200 km, from Aceh in the west end to Halmahera in the east end.

The rest of the other volcanoes in the world that scattered in the island arc and suburban America in the Pacific such as Hawaii and Samoa, and in the islands of the Indian Ocean, the Atlantic such as the Azores, Cape Verde Island, Canada, and Medeira that are the underwater volcanoes, and in the Mediterranean region and Asia Minor in the north and center of the continent, known as the African Rift System.

Sicily’s Mount Etna, the current tallest active volcano in Europe, erupted on 2011 that spewing out ash and shooting spectacular bursts of lava high into the air in the process. (Picture from: http://www.inquisitr.com/)

"For volcanoes are located in subduction on ring of fire zone, the average included in stratovolcano type, which has huge eruption. Including the volcanoes in Japan, which also includes in this type. But Mount Etna that erupted some time ago and Vesuvius's at 1979 in Italy was also included in it, although there are more magma rather than rocks and pyroclastic," said Budi added. *** [EKA | FROM VARIOUS SOURCES | FEBY SYARIFAH | PIKIRAN RAKYAT 14032013]
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The Tidal Lake in Semangko Fault

Andang Bachtiar, former Chairman of the Indonesian Geologists Association (Ikatan Ahli Geologi Indonesia / IAGI), was amazed when he was in around Tarusan Kamang Lake. Understandably, the lake is located in the Kamang Mudiak village, Agam regency, West Sumatra, it may subside for a year, then ​​38 hectares area becoming a stretch of grassland.

Tarusan Kamang Lake. (Picture from: http://www.antarasumbar.com/)

At one time, the water suddenly gushed freely from limestone crevices. The meadow was drowned and a lake which is where the locals could get fish and shrimp with fishing pole and nets. For several months, even up to two years, the lake was not receding.

Imran Malin Mudo (50 years) a resident of Babukik, Kamang Mudiak, explains, since he lived on the banks, the lake can survive pooled maximum of two years. "It can't be expected when the water disappeared," he said. According to the story the old people in the village, the lake could be in a dry condition maximum of 3.5 years. "It happened when the Japanese invaded Indonesia," he said.

Andang Bachtiar. (Picture from:  
http://www.wartablora.com/)

The area of ​​the Tarusan Kamang Lake is not too large. Using an engined-rubber boat, it only takes about 15 minutes to surround it. In some parts of the lake has a depth of less than 2 meters. On the other can reach 10 meters.

For locals, the ebb and flow of water in the Tarusan Kamang Lake is a natural phenomenon ordinary. However, this rare occurrence in the lake that makes the geologists interested in doing research on February 23, 2013. "This is a very interesting phenomenon. Many karst lakes in other parts of Indonesia, but only Tarusan Kamang Lake that have a direct connection with the underground river," said Andang Bachtiar, who is currently the Chairman of the Advisory Board of IAGI. With Nofrins Napilus and Kurnia Chahk, Andang conduct preliminary research on Tarusan Kamang Lake. Also accompany with Indra Catri, the Regent of Agam.

From initial observations, Andang concluded that Tarusan Kamang Lake, as well as karst lakes, is a separate-strain  tectonic lake associated with the Sumatra fault. The fault named Semangko, this great fault divide Sumatra Island. Thus, the lake is located in the Semangko fault zone (Jump to Semangko fault related article).

Tarusan Kamang Lake, when full of water and dry. (Picture from: http://izzawa.wordpress.com/)

The karst lakes, also called doline is the lake that located in the rocky limestone. This type of lake formed by erosion or dissolution of limestone. Former erosion formed basin, which then filled with water, and forming the lake.

"It is certain karst lake because it is below the old age limestone hills, which is 300-400 million years old, older than the age limestone in Java," said Andang. In addition, he found that the lake plains, the grassy green is an alluvial fan that is characteristic of the morphology of the normal active faults.

Northwest-southeast fault, which is part of the Sumatra fault, paired with the east-west fault, which limits the southern part of the lake. Evidence of the presence of an east-west fault this is the direction of fracturing in areas of limestone that is in the lake and alluvial fan that has smaller dimensions.

"This reinforces the notion that Tarusan Kamang Lake, in addition to having properties karst lake, the lake has a component-separating tectonic rift," said Andang. He also took samples of lake sediments, to investigate the age of the lake.

The phenomenon of the dried and filled of the lake's water follow the relating vessel law. This vessel connecting underground rivers, which are at a depth of cliffs and limestone ridges to the east and south of the lake, with low or basin formed from fragments. When the underground water level receded to a level lower than the bottom of the lake, the lake dried up. If the river water level rises, the lake was filled.

In a further observation, Andang was climb as high as 300 meters up the hill, goes into the cave in the karst, and saw the hole water ingress. According to him, at the height of the 100 meters, there is a water hole. In it appears there was an underground river.

When the waters receded, the lake will be dry. If the river water level rises, the lake will be filled. So that needs to be investigated is what the factors that controled the rise and fall of the river water. "There needs to be mapping the caves and underground river underneath it," said Andang.

Underground rivers and Tarusan Kamang lake considered essential for the conservation of water. "So this automated monitoring tool. If the lake rises, it is the absorption of water up to the back of the Bukit Barisan goes well. If the mountain was denuded, will no longer have water up and down," said Andang.

Relationship of Tarusan Kamang Lake with an underground river beneath it. (Picture from: KORAN TEMPO 4160)

Because of the region's unspoiled and full of lush trees, the caves under the hills are still active. In the western part of the lake, right at the foot of the hill, still visible seven aisle and out of the water into the underground river.

Although the lake could dry up at any time, there are still some types of fish and shrimp that inhabit the lake. Fish are considered native of Tarusan Kamang Lake is pantau fish and white bada fish. Pantau fish shape like the tin heads fish. While white bada fish resembling a small fish in the Maninjau Lake. However, both the body color of family Cyprinidae fish are more transparent.

"Both of these fish can adapt to its environment. Therefore, with more transparent body color," said Hafrijal Syandri, a fisheries expert from the Bung Hatta University, Padang. "When the water receded, they were in the hallway of water in the basement and living microorganisms, worms or insects in the cave." While the shrimp are able to live in the waters of the cave as well as eating detritus or micro-organism.

To breed, when to spawn or reproduce, the fish began to fully take advantage of the lake to spawn. This type of fish does not need a substrate to attach eggs and live on the lake to raise a child. "After the fry have more big sizes while the lake dried up, these fish back into the halls of the river," said Hafrijal.

The number of fish and shrimp in the Tarusan Kamang Lake were enough. These animals are commonly captured by citizens and served as side dishes for daily meals. There are also another fishs that entered the lake, such as tilapia and carp. Therefore, at low tide there pools are not deliberately formed and used to preserve fish. *** [FEBRIANTI | KORAN TEMPO 4160]

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Climate Change Could Triggers Volcanism

Recent research shows climate change is causing increased volcanic activity by enabling fault. Marion Jegen and colleagues at GEOMAR Helmholtz Centre for Ocean Research Kiel, Germany, continues to observe the amount of data that appears on a computer screen.

Computers make global warming scenarios related to the melting of polar ice caps and some mountains. German geophysicist also include the results of drilling the seabed at a subduction zone, the waters of Central and South America. "What we found was the opposite of the view of all people today," Jegen said to Livescience on Wednesday (January 2, 2013).

Jegen and geological research team found indications that climate change has increased the frequency of volcanic eruptions. This finding is the opposite of all this research that a volcanic eruption is dramatically changing the climate.

Rapid global warming has
caused an increase in volcanic 
eruptions in the past, a new study 
finds less slippery. (Picture from:
http://www.livescience.com/)

For example, the mass extinction of living things at the end of the Permian period, millions of years ago. Experts believe it happened after the eruption of super-volcanoes that constantly and cool climate and poisoned the atmosphere and oceans.

Climate change is very rapid since a few million years ago. Today, we are entering the end era of of the Ice Age. These changes make the continental glaciers melt and raising sea levels. For example, Sundas began sinking since 10 thousand years so now the Java Sea.

From computer models, glaciers seen melting that reduce pressure on the continent. While sea level rise increases the pressure on the earth's crust on the seafloor. Pressure changes that trigger an increase in volcanic activity.

Ash layers in cores from the Pacific seafloor. (Picture from: http://www.gizmag.com/)

The research team reviewed the results of deep-sea drilling South and Central America. Sediment obtained indicate, within a period of 1 million years there have been drastic changes in the climate.

Every time there is global warming, a layer of volcanic ash (tephra) in the sediments. "In some places, such as in Costa Rica, increased volcanic activity reaches 5-10 times after a period of glaciers melting," said Jegen.

This study did not assess whether modern climate change (referred to as a result of human activity) affect the increased frequency of volcanic eruptions. Although in theory, Jegen said, it's possible.

Worldwide volcanic activity 
increases 1875-1993. (Picture from:
http://bibliotecapleyades.lege.net/)

Jegen explained, will not necessarily climate change followed by a volcanic eruption. He predicts a lag of about 2,500 years. If we change the climate, he said, would not really be certain things happen in a few thousand years later.

Before Jegen and colleagues released the results of their study, the study by the Research Center of the University College London Hazard also concluded the same thing. In August 2007, Bill McGuire from the agency wrote in the Guardian Unlimited. According to McGuire, one of the features that can change the balance of power in the Earth's crust is a layer of ice, in the form of glaciers. This ice sheet covered most of the earth around the poles, plus mountains at all latitudes.

The mass of the ice crust that is pressing on the backfoot. When the ice melts, the crust was no longer have anything on it so it can clamp quickly enough. Rebound is actually happening now, as a result of the end of the last Ice Age.

Areas crust could change and rebound the stresses and enable the fault / fracture and volcanoes. McGuire pointed Iceland, which has a layer of ice in the mountains of the Eyjafjallajokull volcano. "Unloading effects could trigger an eruption," he said.

Average Earth Surface Temperature Changes from
1870 to 1899). (Picture from: https://www.meted.ucar.edu/)

With the dynamics of changes in the earth's crust, faults become unstable. This brings other problems. "It's not just about volcanoes. If you load and unload an active faults, you are responsible for the actions of triggering earthquakes," McGuire said.

He showed some evidence in the event of climate change of the past. At the end of the Ice Age, he said, there was increse massive of seismicity along the edge of the Scandinavian ice sheet. This sparked a large underwater landslide that produced a tsunami.

Roland Burgmann, a geologist at the University of California, Berkeley, agreed that changes in ice cover can have a significant effect on the earth's crust. But he hopes there is more research to explain this phenomenon. And now Marion Jegen and his friends have been answering Burgmann's questions. ***  [EKA |  FROM VARIOUS SOURCES | GIZMAG | [LIVESCIENCE | UNTUNG WIDYANTO | KORAN TEMPO 4108]

Water Pressure

The melting ice raises additional consequences because of all the water eventually empties into the sea. Global warming causes rising sea surface temperatures and the water expands, so-called thermal expansion process.

Improved water mass puts stress on fault / fracture near the shoreline. Added weight of the water on the Earth's crust caused tensional and compression conditions. "Just like when you bend a plank of wood," said Bill McGuire of University College London Research Centre Hazard.

The compression power can push out any magma in the kitchen and triggered the eruption of the volcano. This mechanism is believed to be the cause of the eruption of Pavlof volcano seasonally in Alaska. This mountain erupts every winter when the sea level higher.

McGuire conducted a study published in the journal Nature in 1997. He attributed the relationship between sea level rise and volcanic activity in the Mediterranean over the last 80 thousand years. He found that, when the sea level rose quickly, volcanic eruptions has increased 300 percent.

Global warming is causing the melting of glaciers and sea levels rose so quickly. This geological catastrophe, he is comparable to an increase in sea surface quickly seeara we have seen in the past 15 thousand years. *** [EKA |  FROM VARIOUS SOURCES | GIZMAG | [LIVESCIENCE | UWD | KORAN TEMPO 4108]

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Toba Supervolcano

Walls of the long-since-collapsed Toba volcano on Sumatra island rise behind rice fields. (Picture from: http://news.nationalgeographic.com/)

About 74 thousand years ago, the Toba volcano in Sumatra erupted explosively and cause a global catastrophe. The impact made ​​the Toba eruption of the volcano are classified as supervolcano. Not only ash, Toba send enough sulfuric acid into the atmosphere to create acid rain in the polar regions of the earth.

Samosir Island (center) rose
within the now water-filled
crater of the collapsed Toba 
 volcano. (Picture from:
http://news.nationalgeographic.com/)

This information was obtained after scientists dug residual traces of sulfuric acid in polar ice cores. "We keep track of acid rain in the ice sheets in Greenland and Antarctica," says Anders Svensson, glaciologist from the Niels Bohr Institute at the University of Copenhagen, Denmark, Tuesday November 6, 2012.

Ice cores can provide more detailed evidence about the Earth's climate has changed dramatically in just a few years after the massive eruption of Toba. "There is no uniform global cooling caused by the Toba eruption," said Svensson.

According to him, large temperature fluctuations cooling only found in the northern hemisphere, while in the southern hemisphere warmer. "Global cooling occurred within a short period."

This shows the bipolar matching of volcanic 
acidity spikes (sulphate) in Greenland and 
Antarctic ice cores at around the Toba eruption. 
(Pictures from: http://www.sciencedaily.com/)

New evidence found by Svensson and colleagues promising solution for a number of archaeological debate. The Toba eruption occurred at a critical point in the history of early man when Homo sapiens first came out of Africa into Asia. But there is a clear difference of opinion about the fate of mankind. "Are most of the inhabitants of the earth destroyed by the eruption of that?"

He said layers of volcanic ash from the eruption of Toba have been found in most parts of Asia. The material is used as a guide eruption of ancient archaeological represent a very important civilization which is considered too old to do carbon dating. "The position of the Toba eruption on the ice core record will be put in the context of climate archaeological finds. This will help explain the critical period of human history," said Svensson. Detail the research is published in the journal Climate of the Past. *** [LIVESCIENCE | MAHARDIKA SATRIA HADI | KORAN TEMPO 4049]

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Is It True That Human Activity Can Trigger an Earthquake?

Years ago there was an earthquake measuring 5.1 on the Richter scale in Spain that killed nine peoples. Apparently the quake was not caused by a collision of the plates or fracture / fault. The trigger is pumping water for decades of underground water sources near the center of the quake.

"It suggests human activity played a role in moving the earth's crust," said Pablo Gonzalez of the University of Western Ontario, Tuesday, October 23, 2012.

Are we destablising the ground
beneath our feet? (Picture from:
 http://www.newscientist.com/)

Gonzalez and his colleagues examined the link between earthquakes and the decline of groundwater levels in water reservoirs (aquifers) in the basement. For this condition Gonzalez theorized could create pressures that led to the quake.

Research published in the journal Nature Geoscience focused on the earthquake in Lorca, a region in southern Spain, on May 11, 2011. The quake was not large relative strength is not only claimed nine lives, but also damaged many buildings in the farming areas.

To test the theory, Gonzalez and his colleagues used satellite data to see ground deformation caused by the earthquake. They found that the deformation was associated with a shift in the earth's crust due to the natural decline in groundwater levels. "The reduction is as deep as 250 meters during five decades as groundwater extraction," said Gonzalez.

Their findings suggest that the pressure of human activities on faults near Lorca (known as the Alhama de Murcia fault) not only can cause earthquakes. Human intervention also affects how much delivery will slip. Lorca groundwater tapped by the wells in order to irrigate plantations of fruit and vegetables and livestock drinking water.

May 2011: The earthquake in Lorca killed nine people and destroyed hundreds of homes. (Picture from: http://www.telegraph.co.uk/)

Gonzalez said that the study could offer clues about the future earthquake near water sources. "We should be wary of dams, aquifers, and the melting of glaciers that are located close to the tectonic fault," he said.

Nevertheless, at Lorca different phenomena minor earthquakes in Texas for two years. Some of these earthquakes occurred near wastewater disposal wells deep deep underground.

In an accompanying article, Jean-Philippe Avouac of the California Institute of Technology said the implications could be far-reaching "if ever the effect of human-induced stress perturbations on seismicity is fully understood".

"For now, we should remain cautious... we know how to start earthquakes, but we are still far from being able to keep them under control," Avouac wrote.. *** [REUTERS | MAHARDIKA SATRIA HADI | KORAN TEMPO 4036]

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