A new chain of barrier islands has been discovered in one the highest wave energy environments on Earth. The 90-km-long chain of sandy barrier islands flanks the western shore of Scotland's Western Isles (Outer Hebrides). Uniquely among barrier islands, these are migrating over a solid bedrock surface and the shape of the underlying surface is fundamental in controlling their response to rising sea level. In some parts, the islands resemble typical barrier islands with tidal inlets and deltas, but where the bedrock surface is high, the islands enclose perched lagoons and lack tidal deltas. The planar bedrock surface is crucial in permitting barrier islands to form in such high energy settings -- it reduces incoming wave energy to the point that islands can stabilize.
Early signals of new volcanic unrest at Campi Flegrei caldera? Insights from geochemical data and physical simulations
Giovanni Chiodini et al., Istituto Nazionale di Geofisica e Vulcanologia, Osservatorio Vesuviano, via Diocleziano 328, 80124 Naples, Italy. Posted online 23 July 2012; doi: 10.1130/G33251.1.
Many hundreds of thousands people live at Campi Flegrei, a caldera located near Naples, Italy, which had a large ground inflation in 1982-1984 followed by twenty years of subsidence. Recently, the behavior of the volcano has changed: the fumaroles have increased in activity; swarms of low-magnitude earthquakes have become more frequent; and the ground started a new general uplifting trend, indicating that the system is undergoing repeated injections of magmatic fluid. Physical simulations of the process show that total injected fluid masses are the same order of magnitude as those emitted during small to medium size volcanic eruptions, and their cumulative curve highlights a current period of increasing activity.
Upper plate tectonic stress state may influence interseismic cou
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Geological Society of America