Iceland and Philippine volcanoes shaken by earthquakes

July 18, 2011MANILA – The Philippine Institute of Volcanology and Seismology (Phivolcs) said quakes rocked Taal Volcano in Batangas and Negros Occidental province in Western Visayas on Monday. Phivolcs said a magnitude-5 quake jolted Negros Occidental province in Western Visayas Monday morning, nearly a week after a magnitude-6.2 quake hit the area. Meanwhile, at least five volcanic quakes were recorded at restive Taal Volcano in Batangas in the last 24 hours, Phivolcs said. Phivolcs said the quake was recorded at 8:43 a.m. and was tectonic in origin. In its bulletin, Phivolcs said the epicenter was 61 km southwest of Cauayan, Negros Occidental. Authorities issued a warning that the public, however, is reminded that the Main Crater should be strictly off-limits to the public because sudden steam explosions may occur and high concentrations of toxic gases may accumulate.  –GMA News


Iceland: A small earthquake swarm was also detected under the Katla volcano. The swarm was led by the most powerful earthquake in the series which measured a 3.8 in magnitude and occurred at the shallow depth of about 1 km below the volcano. Activity has been increasing at the volcano over the last two week. –The Extinction Protocol
contribution Luisport
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6 Responses to Iceland and Philippine volcanoes shaken by earthquakes

  1. Dennis says:

    Alvin: Dennis here with an off-post question regarding magma.
    This my question. Disregarding Yellowstone and other places in the Western US that geologists know where that there is magma, to your knowledge, is there any other place in the US that a magma chamber has been located or magma is moving to? For example, Midwest USA, Northeast USA, you know.



    • Since magma is under all the Earth’ it has more direct access points through what we call magma plumes or ‘hotspots’ though magma can snake its way anywhere from no discernable chamber. The Long Valley Caldera in California is one example of that. The source of its magma is unknown. We find volcanoes by studying the past…and that has been the basis of our research in geology. If there never was an eruption or quakes now; it’s possible one could be dormant but since Earth’s past history had high geological activity, most volcanoes have left foot-prints from prior activity. The La Garita caldera (super-volcano), which was one of the largest eruptions thought to have ever occurred on Earth, similarly had no distinct magma chamber plume.


  2. luisport says:
    Helgi Björnsson geophysicist says there is every reason to monitor the area of Mýrdalsjökull glacier well, there are daily changes going on.
    The area where the 3,8 earthquake hit was overflown by a helicopter. There are no signs of eruption or upheaval at that spot. However there have been considerable changes in the glacier in the days since the flooding in Múlakvísl took place.
    The calderas have become deeper and the cracks or crevises around them larger.


  3. luisport says:

    Katla seismicity

    By Heidi Soosalu

    The Katla volcano under the Mýrdalsjökull glacier is known to have seasonal seismic activity – earthquakes concentrate to the latter part of the year. The seismicity is interpreted to be related to the deloading of the thin crust above the magma chamber due to the summer melting of the ice cap, and to high groundwater pressure in the caldera roof at the same time.

    There are two distinct seismic areas under Mýrdalsjökull. The most active area is located at the Goðabunga rise in the western part of the glacier, and the other one in the Katla caldera in the middle part. The earthquakes in both of the places are volcanic in nature. They start with rather high frequencies, and the onset can be anything from clearly impulsive to emergent. The continuation of the signal consists of lower frequencies only. No clear S-wave are seen in most of the seismic records, especially not in the signals from Goðabunga.

    Due to the nature of the Katla events it is somewhat difficult to estimate their magnitudes. However, they are seldom larger than local magnitude (ML) 4. It is worth noticing that the local population rarely feels Katla earthquakes, though inhabited areas are situated quite near. The depths of the Katla events are difficult to estimate, as well, but they seem to be shallow, within 0-5 km.

    Since 1999 Katla has been showing signs of unrest. In July 1999 a small glacial flood lasting less than 24 hours was observed. It is possible that it was caused by an intrusion of magma or even a small subglacial eruption. So far this has not been followed by further eruptive activity. The seismicity in the year 1999, on the other hand, had the typical seasonal pattern and was not exceptional. During the year 2002 the seismic activity in the Katla area has risen dramatically. In the spring the earthquakes of the fall 2001 did not cease to occur in a typical manner, but continued throughout the year on a daily basis. Their magnitudes have been mostly below 2.5, but a couple of events larger than ML 3 have been observed.


  4. Girls says:

    This surely makes perfect sense to anyone!!


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