Sunday, June 30, 2013

GLOBAL VOLCANISM: Kilauea's Eruption Continues Apace With Two Ocean Entry Points!

June 30, 2013 - HAWAII - Breakouts from the Kahaualea 2 lava flow burned forest areas north of Kilauea’s middle east rift zone today as eruption activity continued with little change. Tiltmeters at the Kilauea summit recorded only minor fluctuations, according to the U.S. Geological Survey’s Hawaiian Volcano Observatory. Seismic tremor levels were also low, according to the observatory.




The tiltmeter at Puu Oo cone in the middle east rift zone also recorded only minor fluctuations. According to the observatory, the northeast spatter cone continued to feed the Kahaualea 2 flow, which extended about 1.6 miles to the north. Breakouts fro the flow burned forest at the north edge of a flow field created between 1983 and 1986.

A second active front, about 1.2 miles north-northwest of Puu Oo, expanded to the west and burned the edge of the forest to the north, the observatory reported. Meanwhile, the so-called Peace Day flow fed a pair of ocean entries via lava tubes. The main entry area was just east of the Hawaii Volcanoes National Park boundary; a smaller entry was located just inside the park.

Lava lakes are large volumes of molten lava, usually basaltic, contained in a volcanic vent, crater, or broad depression. The term is used to describe both lava lakes that are wholly or partly molten and those that are solidified (sometimes referred to as frozen lava lakes in this case).

There is a lava lake in Marum crater, Ambrym in Vanuatu. Hawaii’s Kilauea has the distinction of having two persistent lava lakes: one in the Halemaʻumaʻu vent cavity within the summit caldera, and another located within the Puʻu ʻŌʻō cone located on the east rift zone of the volcano.

The number of lava lakes being reported in volcanoes has increased dramatically in the last 25 years, suggesting more magma from the planet’s interior is seeping towards the surface. - Star Advertiser.






GLOBAL VOLCANISM: New Research - Mega-Quakes Caused Volcanoes In Earth's Subduction Zones To Sink!

June 30, 2013 - EARTH - Massive earthquakes can cause distant volcanoes to sink, according to research in Japan and Chile published on Sunday. The magnitude 9.0 tsunami-generating quake that occurred off northeastern Japan in 2011 caused subsidence of up to 15 centimeters (9.3 inches) in a string of volcanoes on the island of Honshu as much as 200 kilometers (120 miles) from the epicenter, a Japanese study said.




And the 8.8 magnitude Maule quake in Chile in 2010 caused a similar degree of sinking in five volcanic regions located up to 220km (130 miles) away, according to a US-led paper. It was not clear whether the phenomenon boosted eruption risk, the authors wrote. Both the Japan and Chile quakes were of the subduction type, caused when one part of Earth’s crust slides beneath another. If the movement is not smooth, tension can build up over decades or centuries before it is suddenly released, sometimes with catastrophic effect. In both cases, the sinking occurred in mountain ranges running horizontally to the quake.

The 2011 quake “caused east-west tension in eastern Japan,” Youichiro Takada of the Disaster Prevention Research Institute at Kyoto University told AFP in an email. “Hot and soft rocks beneath the volcanoes, with magma at the centre, were horizontally stretched and vertically flattened. This deformation caused the volcanoes to subside.” The researchers for the Chilean volcanoes said subsidence occurred along a stretch spanning 400km (250 miles).

As in Japan, the ground deformation in Chile occurred in huge ellipse-shaped divots up to 15km by 30km (nine miles by 18 miles) in size, although the cause appears to be different. Pockets of hot hydrothermal fluids that underpinned the volcanic areas may have escaped through rock that had been stretched and made permeable by the quake.

Two earthquakes in the Chilean subduction zone in 1906 and 1960 were followed by eruptions in the Andean southern volcanic zone within a year of their occurrence. However, no big eruptions in this volcanic hotspot can be associated with the 2010 temblor, says the study led by Matthew Pritchard of Cornell University in New York. Takada said the impact of the 2011 quake on volcano risk on Honshu was unclear.

“At this stage we do not know the relation between volcanic eruption and the subsidence we found. Further understanding of the magmatic movement would be necessary,” he said. The subsidence in Japan was spotted at the volcanoes Akitakoma, which last erupted in 1971; Kurikoma (1950); Zao (1940); Azuma (1977); and Nasu (1963). The studies, published in the journal Nature Geoscience, used data from satellite radar which mapped terrain before and after the quakes. - Times of India.