A small number of islands are rising out of the sea when our theory of geological processes suggest they should be sinking beneath the waves . The most dramatic case of this is Santa Maria in the Azores . A young paper provides an explanation for its growth , and possibly that of other islands make ground against the odds .
pelagic islands are pushed up by volcanic activity beneath . finally , the volcanism stops and islands start to lapse from a compounding of erosion and changes to the continental crust on which they lie . Rising ocean level mean that , proportional to the water line , islands worldwide are sinking much faster today .
Although there are a small bit of exceptions around the world , most of these are for rationality we have understood for a while , such as bulge appearing in the seafloor beneath the island in response to things happen elsewhere . In theGeology Society of America Bulletin , a team leave by the University of Bristol’sDr Ricardo Ramalhoexplain Santa Maria ’s anomalous growth to magma intrusions causing a thickening of the crust beneath it .
Ramalho previously attracted attention with the breakthrough that the Cape Verde Islands , far to Santa Maria ’s Dixie , have been struck by tsunamis thesize of skyscraper . His piece of work on Santa Maria is much less striking , but usingArgon / Argon datinghe was able to appraise the island as being 6 million years quondam , younger than premature estimates but still the oldest island in the Azores .
After an initial period of growth , come by subsidence , Ramalho found Santa Maria was partly or totally submerge from 5.3 - 4.1 million years ago . It started rising again 3.5 million geezerhood ago .
Santa Maria ’s upthrust is particularly surprising because beleaguer islands are sinking . After considering , and decree out , a number of other possible explanations for this anomalous rise , Ramalho was leave with one possibility . “ Magma , instead of rising to the surface , started to accumulate below the island , slowly lead to jack the volcano upwards , ” Ramalho explained in astatement .
The determination leaf unanswered the inquiry of what could be causing this accumulation of magma , which is in particular unexpected give the relative youth of the crust on which Santa Maria stand . Ramalho is slap-up to take other locations where interchangeable processes may be come about .
The rate of increase is unconvincing to earmark Santa Maria to outrun ocean point raise over the next few tenner , but with a maximum acme of 580 meters ( 1,900 foot ) , the island ’s 5,500 inhabitants have plenty of place to retreat to if their towns get lap away , and the summons should be a little slower than for people at standardized elevation elsewhere in the world .
