Satellite measurements reveal gravity dip from ice loss in West Antarctica

Although not designed to map changes in Earth's gravity over time, ESA's extraordinary GOCE satellite has shown that the ice lost from West Antarctica over the last few years has left its signature.

More than doubling its planned life in orbit, GOCE spent four years measuring Earth's gravity in unprecedented detail.

Scientists are now armed with the most accurate gravity model ever produced. This is leading to a much better understanding of many facets of our planet -- from the boundary between Earth's crust and upper mantle to the density of the upper atmosphere.

The strength of gravity at Earth's surface varies subtly from place to place owing to factors such as the planet's rotation and the position of mountains and ocean trenches.

Changes in the mass of large ice sheets can also cause small local variations in gravity.

Recently, the high-resolution measurements from GOCE over Antarctica between November 2009 and June 2012 have been analysed by scientists from the German Geodetic Research Institute, Delft University of Technology in the Netherlands, the Jet Propulsion Lab in USA and the Technical University of Munich in Germany.

Remarkably, they found that the decrease in the mass of ice during this period was mirrored in GOCE's measurements, even though the mission was not designed to detect changes over time.

Using gravity data to assess changes in ice mass is not new. The NASA-German Grace satellite, which was designed to measure change, has been providing this information for over 10 years.

However, measurements from Grace are much coarser than those of GOCE, so they cannot be used to look at features such as Antarctica's smaller 'catchment basins'.

For scientific purposes, the Antarctic ice sheet is often divided into catchment basins so that comparative measurements can be taken to work out how the ice in each basin is changing and discharging ice to the oceans. Some basins are much bigger than others.

By combining GOCE's high-resolution measurements with information from Grace, scientists can now look at changes in ice mass in small glacial systems -- offering even greater insight into the dynamics of Antarctica's different basins.

They have found that that the loss of ice from West Antarctica between 2009 and 2012 caused a dip in the gravity field over the region.

In addition, GOCE data could be used to help validate satellite altimetry measurements for an even clearer understanding of ice-sheet and sea-level change.

ESA's CryoSat satellite, which carries a radar altimeter, has recently shown that since 2009 the rate at which ice is been lost from the West Antarctic Ice Sheet every year has increased by a factor of three.

And, between 2011 and 2014, Antarctica as a whole has been shrinking in volume by 125 cubic kilometres a year.

Johannes Bouman from the German Geodetic Research Institute said, "We are now working in an interdisciplinary team to extend the analysis of GOCE's data to all of Antarctica.

"This will help us gain further comparison with results from CryoSat for an even more reliable picture of actual changes in ice mass."

This new research into GOCE's gravity data revealing ice loss over time is being carried out through ESA's Earth Observation Support to Science Element.

Fascinating Facts

What is the deepest part of the ocean?

The average depth of the oceans is about five times the average elevation of the land. In general, the continents stand about three miles above the ocean floor. According to the National Geographic Atlas, the deepest-known part of the ocean measures 10,924 meters (35,839 feet), in the Marianas Trench near Guam. If the world's highest mountain, Mount Everest (29,141 feet), were to be placed into this trench, it would be covered by over 1.25 miles of water.

Which countries have the largest area?

1	Russia - 6.6 million sq.mi (17 million sq.km)
2	Canada - 3.9 million sq.mi (9.9 million sq.km)
3	China - 3.7 million sq.mi (9.6 million sq.km)
4	United States- 3.7 million sq.mi (9.6 million sq.km)
5	Brazil - 3.3 million sq.mi (8.5 million sq.km)
6	Australia - 3 million sq.mi (7.6 million sq.km)
7	India 1.2 million sq.mi (3 million sq.km)
8	Argentina 1.1 million sq.mi (2.7 million sq.km)
9	Kazakhstan 1,050,000 sq.mi (2.7 million sq.km)
	10 Sudan 966,000 sq.mi (2.4 million sq.km) What is geography? Geography is much more than a list of the countries of the world. It is so much more than that. As it is defined by the American Heritage dictionary, geography is the study of the earth and its features and of the distribution of life on the earth, including human life and the effects of human activity. How fast is the world's population growing? The world's current growth rate is about 1.3%, representing a doubling time of 54 years. We can expect the world's population of approximately 6 billion to become 12 billion by 2054 if the current rate of growth continues. The world's growth rate peaked in the 1960s at 2% and a doubling time of 35 years. What is the tallest mountain (highest point) on each continent? The tallest mountain on earth is Mount Everest in Nepal at 29,035 feet. The tallest mountian on each continent is as follows: Mount Everest , Asia - 29,035 feet Cerro Aconcagua, South America - 22,834 feet Mount McKinley (Denali), North America - 20,320 feet Kilimanjaro, Africa - 19,340 feet El'brus, Europe - 18,510 feet Vinson Massif, Antarctica - 16,067 feet Mount Kosciuszko, Australia - 7,310 feet I hope you like these facts and please share this with all your friends!

Life in the Arctic

http://www.bbc.co.uk/programmes/p0115dl0

Life in the Arctic is tough. Find out more in this short video about how people live and adapt to harsh environments!

Dharavi- Facts and Figures

Dharavi, often described as the largest slum in Asia, is a 427 acre triangular stretch of land in central Mumbai, housing more than 600,000 slum dwellers; the unofficial number can go near a million. It is a conglomeration of continuous settlements, separated by a small road or sometimes a wall - constructed hastily at times of conflict. Dharavi is literally sandwiched between the Western and Central suburban railway lines with Mahim and Bandra to its west, Mithi River to the north and Sion and Matunga to its east and south respectively. Mahim, Matunga and Sion railway stations mark its three corners.
Dharavi has had settlements since the beginning of the 18th century, which comprised Kolis or the fisher folk, who lived at the edge of the creek that came in from the Arabian Sea. The Gazetteer of Bombay City and Island in 1909 had mentioned Dharavi as one of the 'six great Koliwadas of Bombay'. It is thought that the present day Dharavi also includes the land obtained by the accidental drying up of the creek that happened over a period of time.

Of the 10 million people living in the mega city Mumbai, 6 million (60%) are living in the slums, many of them living in Dharavi itself.

The Government:

The government of Mumbai are trying to clear the slums but the problem is slum dwellers like where they are, and don’t want to move. For many of them, they haven’t known any other home, it’s what they are used, what they think home is. They don’t want to move because they have communities they don’t want to leave.

The government are offering land developers free land on a deal. If they can offer the slum dwellers living on the land somewhere to call home they can do what they like with the slums. However this is a difficult thing to do because of the slum dwellers who won’t move out.

• The first settlers in Dharavi came there over 300 years ago, and turned marshland into liveable land; today Dharavi is home to over 500,000 people of all religions, castes and economic strata, not just the 'poor'.
• Almost none of the people who live in Dharavi own the land, but a great many own their homes and businesses (some of which they rent out); many houses have electricity which they pay for, and some have running water.
• Nevertheless, infrastructure is poor: few residents have toilets in their homes; open sewer lines spread disease and are a health hazard in the monsoon.
• Home to thousands of industries, including leather, pottery, textiles, food production and now a major hub of recycling, there is over US $600 million of turnover; unfortunately some of these industries pollute the environment and are unsafe for workers.
• The current redevelopment plan will give slum dwellers who own their structure a new 300 sq ft flat in Dharavi for free; those who rent will have to go elsewhere. Business owners will receive 250 sq ft, and will have to pay for anything more than that.
• The redevelopment has been divided into five sectors, which developers will bid for in a competitive process. Developers need to build housing for slum residents, and they will also
  
  be able to build more lucrative residential buildings and commercial properties.

Stop the disasters

I recommend this website, you can play games where you have to protect a city from tsunamis, floods, earthquakes and more... www.stopdisarersgame.org/

Japan 2011 Tsunami and Earthquake Effects

• The effects of this tragic event are:
• On March the 11th of 2011, a magnitude 9 earthquake shook Japan.
• This was felt from Norway through to Antarctica.
• Tsunami debris continues to wash up on North American beaches to this day. 

• Fukushima Power plant suffered a level 7 nuclear meltdown after the tsunami.
• Two years after the quake, 300 000 people are still living in temporary homes because they lost theirs.
• The earthquake only lasted 5 minutes but caused so much damage.
• The tsunami only happened 20 minutes later so people had little time to escape with their lives even with a warning system.
• The tsunami went over the 10m wall in Japan because some of it sunk into the ground because there was so much pressure.
• The unexpected disaster was neither the largest nor deadliest earthquake and tsunami to strike this century. That record goes to the 2004 Banda-Aceh earthquake and tsunami in Sumatra, a magnitude-9.1, which killed more than 230,000 people. But Japan's one-two punch proved especially devastating for the earthquake-savvy country, because few scientists had predicted the country would experience such a large earthquake and tsunami.
  Japan's scientists had predicted a smaller earthquake would strike the northern region of Honshu, the country's main island. Nor did they expect such a large tsunami. But there had been hints of the disaster to come. The areas flooded in 2011 closely matched those of a tsunami that hit Sendai in 869. In the decade before the 2011 Tohoku earthquake, a handful of Japanese geologists had begun to recognize that a large earthquake and tsunami had struck the northern Honshu region in 869. However, their warnings went unheeded by officials responsible for the country's earthquake hazard assessments. Now, tsunami experts from around the world have been asked to assess the history of past tsunamis in Japan, to better predict the country's future earthquake risk.
  

  The cause

  The 2011 Tohoku earthquake struck offshore of Japan, along a subduction zone where two of Earth's tectonic plates collide. In a subduction zone, one plate slides beneath another into the mantle, the hotter layer beneath the crust. The great plates stick and slip, causing earthquakes. East of Japan, the Pacific plate dives beneath the overriding Eurasian plate. The temblor completely released centuries of built up stress between the two tectonic plates, a recent study found.
  The earthquake started on a Friday at 2:46 p.m. local time (5:46 a.m. UTC). It was centered on the seafloor 45 miles (72 kilometers) east of Tohoku, at a depth of 20 miles (32 km) below the surface. The shaking lasted about six minutes.
  - See more at: http://www.livescience.com/39110-japan-2011-earthquake-tsunami-facts.html#sthash.zyKtaEfU.dpuf
   More than 1,000 aftershocks hit Japan after the earthquake, the largest a magnitude 9.
• About 250 miles of Japan's main island of Honshu moved eastward by 8 feet from the jolt.
• The Pacific plate slid westward near the epicenter by 79 feet.
• The tsunami broke Icebergs off the Sulzberger Ice shelf in Antarctica.
• It happened at 12:46 and killed 19,000 people.
• Areas as far away as Chile and the USA reported a tsunami surge over 6 feet.
• By the time the tsunami reached Hawaii it was so small.
  
  The unexpected disaster was neither the largest nor deadliest earthquake and tsunami to strike this century. That record goes to the 2004 Banda-Aceh earthquake and tsunami in Sumatra, a magnitude-9.1, which killed more than 230,000 people. But Japan's one-two punch proved especially devastating for the earthquake-savvy country, because few scientists had predicted the country would experience such a large earthquake and tsunami.
  Japan's scientists had predicted a smaller earthquake would strike the northern region of Honshu, the country's main island. Nor did they expect such a large tsunami. But there had been hints of the disaster to come. The areas flooded in 2011 closely matched those of a tsunami that hit Sendai in 869. In the decade before the 2011 Tohoku earthquake, a handful of Japanese geologists had begun to recognize that a large earthquake and tsunami had struck the northern Honshu region in 869. However, their warnings went unheeded by officials responsible for the country's earthquake hazard assessments. Now, tsunami experts from around the world have been asked to assess the history of past tsunamis in Japan, to better predict the country's future earthquake risk.
  

  The cause

  The 2011 Tohoku earthquake struck offshore of Japan, along a subduction zone where two of Earth's tectonic plates collide. In a subduction zone, one plate slides beneath another into the mantle, the hotter layer beneath the crust. The great plates stick and slip, causing earthquakes. East of Japan, the Pacific plate dives beneath the overriding Eurasian plate. The temblor completely released centuries of built up stress between the two tectonic plates, a recent study found.
  The earthquake started on a Friday at 2:46 p.m. local time (5:46 a.m. UTC). It was centered on the seafloor 45 miles (72 kilometers) east of Tohoku, at a depth of 20 miles (32 km) below the surface. The shaking lasted about six minutes.
  - See more at: http://www.livescience.com/39110-japan-2011-earthquake-tsunami-facts.html#sthash.zyKtaEfU.dpuf

In Japan, residents are still recovering from the disaster. Radioactive water was recently discovered leaking from the Fukushima Daiichi Nuclear Power Plant, which suffered a level 7 nuclear meltdown after the tsunami. Japan relies on nuclear power, and many of the country's nuclear reactors remain closed because of stricter seismic safety standards since the earthquake. Two years after the quake, about 300,000 people who lost their homes were still living in temporary housing, the Japanese government said. - See more at: http://www.livescience.com/39110-japan-2011-earthquake-tsunami-facts.html#sthash.RfkwIkLG.dpuf

In Japan, residents are still recovering from the disaster. Radioactive water was recently discovered leaking from the Fukushima Daiichi Nuclear Power Plant, which suffered a level 7 nuclear meltdown after the tsunami. Japan relies on nuclear power, and many of the country's nuclear reactors remain closed because of stricter seismic safety standards since the earthquake. Two years after the quake, about 300,000 people who lost their homes were still living in temporary housing, the Japanese government said. - See more at: http://www.livescience.com/39110-japan-2011-earthquake-tsunami-facts.html#sthash.RfkwIkLG.dpuf

On March 11, 2011, a magnitude-9 earthquake shook northeastern Japan, unleashing a savage tsunami.
The effects of the great earthquake were felt around the world, from Norway's fjords to Antarctica's ice sheet. Tsunami debris continues to wash up on North American beaches two years later.
- See more at: http://www.livescience.com/39110-japan-2011-earthquake-tsunami-facts.html#sthash.RfkwIkLG.dpuf

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On March 11, 2011, a magnitude-9 earthquake shook northeastern Japan, unleashing a savage tsunami.
The effects of the great earthquake were felt around the world, from Norway's fjords to Antarctica's ice sheet. Tsunami debris continues to wash up on North American beaches two years later.
- See more at: http://www.livescience.com/39110-japan-2011-earthquake-tsunami-facts.html#sthash.VmWjcwso.dpuf

On March 11, 2011, a magnitude-9 earthquake shook northeastern Japan, unleashing a savage tsunami.
The effects of the great earthquake were felt around the world, from Norway's fjords to Antarctica's ice sheet. Tsunami debris continues to wash up on North American beaches two years later.
- See more at: http://www.livescience.com/39110-japan-2011-earthquake-tsunami-facts.html#sthash.VmWjcwso.dpuf