w orldwatch n Did a Google Maps error spark Nicaraguan invasion?: Reports that an error on Google Maps was to blame for Nicaraguan troops invading and occupying a Costa Rican island were being questioned as Geographical went to press.
n early November, around 50 Nicaraguan soldiers set up camp on Isla Calero, a small island located in the delta of the San Juan River on the Atlantic coast. The soldiers lowered the Costa Rican flag and replaced it with a Nicaraguan flag.
When questioned about the incursion, the group’s commander, Eden Pastora, told Costa Rica’s largest newspaper, La Nacion, that Google Maps was to blame, pointing out that the map on the site clearly placed the island on Nicaragua’s side of the border. Nicaraguan government officials repeated the claim that a ‘bug in Google’ was at fault.
owever, several weeks after the incursion, the soldiers were still occupying the island, and doubts were being raised about the seriousness of the original explanation. Suggestions for an alternative included attempts by Nicaragua’s president, Daniel Ortega, to hold on to power, and a plan by Venezuela, Iran and Nicaragua to create a ‘Nicaragua Canal’ between the Atlantic and Pacific oceans.
he San Juan River marks the eastern third of the border between Nicaragua and Costa Rica; the river itself belongs to Nicaragua, and Costa Rica’s territory begins at its southern bank. Not long before the invasion, Ortega argued that the island should belong to his country, since Nicaragua owns the river and the island is made up of silt from the river.
n New crust being formed in novel way: Scientists at the Woods Hole Oceanographic Institution (WHOI) have observed ocean crust forming almost ten times farther away from an active ocean ridge than previously recorded.
cean crust is usually formed as magma bubbles up through volcano-like openings in a narrow (about five-kilometre-wide) zone along the boundaries between two plates that are pulling away from each other. Working at the Guaymas Basin in the Gulf of California, the WHOI scientists used a sound-wave-emitting air gun, side-scan sonar and ocean-floor cameras to confirm that magma was forming sills within the top one or two kilometres of the thick layer of sediment that fills the basin, about 50 kilometres away from the plate boundary.
he process has important implications for the local marine life, as well as the carbon cycle. The heat from the rising magma releases nutrient-rich fluid from within the sediments that is feeding communities of sea creatures similar to those found around vent sites near deep-water mid-ocean ridges. It also causes the release of significant amounts of carbon from the sediments – around ten times more carbon dioxide and methane than a similar volume of volcanic rock emerging from a vent.
he researchers suspect that the phenomenon is not restricted to the Gulf of California, but is almost certainly taking place in other sites.
Woods Hole Oceanographic Institution scientist examines a sample of ocean crust
Magma movement caused Icelandic eruption
The reawakening and subsequent eruption of Iceland’s Eyjafjallajökull volcano in March and April last year may have been triggered by the explosive meeting of two types of magma flowing beneath the volcano, according to an international team of scientists.
n a paper published in Nature, the researchers describe their analysis of geophysical changes that took place in the long-dormant volcano prior to its eruption. ‘Several months of unrest preceded the eruptions, with magma moving around downstairs in the plumbing and making noise in the form of earthquakes,’ said one of the study’s authors, Kurt Feigl of the University of Wisconsin-Madison.
The researchers used a combination of satellite imagery and GPS surveys to track the deformation of the volcano’s edifice. The results showed that the volcano swelled for 11 weeks before it first began to erupt, expanding by more than 15 centimetres as magma flowed into shallow chambers beneath the mountain.
fter the initial eruption, the researchers believe that the fresh magma came into contact with a different type of magma, perhaps left over from the last eruption, which took place 200 years ago. The differences in temperature, composition and gas content probably triggered the more explosive second eruption.
The researchers are now using data from an array of sensors around the volcano to map the chambers and other structures within it. ‘We’re a long way from being able to predict eruptions, but if we can visualise the magma as it moves upwards inside the volcano, then we’ll improve our understanding of the processes driving volcanic activity,’ Feigel said.
Hole inst/Woods ind
;Tom shut terstock
12 www.geographical.co.uk january 2011
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