Axial Seamount Erupts

Posted by matt on 2015-05-01
Posted in: America N, Eruptions-present. Tagged: , , , . 50 Comments
axial_med

Cabled array at Axial seamount

On April 30, 2015, Axial seamount erupted.  The good news is that this volcano is little threat to anyone.  The pressure of the deep ocean above this volcano prevents any explosion from being observed on the surface.  So why is this significant?  The NOAA successfully predicted this eruption. This is the site of the New Millennium Observatory(NeMO), the first underwater volcano observatory, which is linked to land via a cabled array of sensors.  These sensors detected significant inflation at this volcano prior to the eruption, followed by rapid deflation and a significant increase in water temperatures at the time of the eruption.

Axial_geodetic_time_series_2015-Apr-sm

Inflation at Axial seamount… and rapid deflation!

Axial Seamount is geologically interesting, because it is caused by a hotspot beneath a ridge.  This hotspot is responsible for the Cobb–Eickelberg Seamount chain, and it lies directly beneath the Juan de Fuca ridge.  It is also one of the few places where a seamount or a midocean ridge is close enough to land to perform a detailed geological study with modern seismic instruments.  After the last eruption in 2011, we got some interesting pictures, such as one of their instruments being buried by a lava flow.  Hopefully, we will be getting more shortly!

OBH_buried

Hydrophone buried under lava flow after 2011 eruption

Matt

 

50 comments on “Axial Seamount Erupts”

  5. A large earthquake PNG.

    Magnitude Mw 7.4
    Region NEW BRITAIN REGION, P.N.G.
    Date time 2015-05-05 01:44:08.7 UTC
    Location 5.89 S ; 151.90 E
    Depth 40 km

    Followed by a 5.8 10 minutes later.

    Magnitude M 5.8
    Region NEW BRITAIN REGION, P.N.G.
    Date time 2015-05-05 01:53:59.5 UTC
    Location 5.29 S ; 152.04 E
    Depth 10 km

    http://www.emsc-csem.org/#2w

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    • Yes, this must have caused damage too, and the awful lot of strong aftershocks! And they had an M 7 only on May 1st.

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  7. Does anyone know the composition of axial seamount lava?, is it the same basalt that juan de fuca produces?

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    • Found this on the internet hope it helps.

      ..The differences in composition between the Axial seamount lavas and the Juan de Fuca Ridge lavas are attributed to melting processes rather than to any fundamental differences in their mantle source compositions. The higher magma production rates, higher Sr, and lower silica saturation in the seamount lavas relative to the ridge lavas are thought to be a consequence of melt initiation at greater depths. The melting column producing the seamount lavas is thought to be initiated in the stability field of spinel peridotite, whereas the ridge lavas are produced from a melting column initiated at shallower levels, possibly within or close to the stability field of plagioclase peridotite. Implicit in this interpretation is the conclusion that the Juan de Fuca Ridge lavas, and by analogy most MORB, are generated at shallow mantle levels, mostly within the stability field of plagioclase peridotite. This interpretation also requires that for the upwelling mantle to intersect the solidus at different depths, the mantle supplying Axial seamount must be hotter than the rest of the Juan de Fuca Ridge.

      http://www.researchgate.net/publication/255896388_Geochemistry_of_Axial_seamount_lavas_Magmatic_relationship_between_the_Cobb_hotspot_and_the_Juan_de_Fuca_Ridge

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  8. I have checked on the Azores EQ swarm on the link Janet provided, and they had an update on it:
    Seismic activity WNW of Faial (Update 04 May 2015)
    CIVISA reports that since 19 April has been recorded increased seismic activity in the region between 37 and 46 km WNW of Faial, the highest a 4.7 ML. Since May 1 that seismic activity has become persistent with some brief episodes of increased hourly frequency of events, showing no significant changes. During the day, up to 19:00, were recorded 61 events. The number of events recorded since the beginning of seismic activity is about 421.
    Under the geological point of view, the area is located near the extreme north-western border of plates between the Eurasian plate and the African plate (Nubia), in the transition zone to the region dominated by the plate boundary defined by the Mid-Atlantic Ridge. The CIVISA continues to monitor the developments.

    Not that I want to scaremonger, but why would they not take volcanic activity into consideration? I mean, 421 in 2 weeks is quite a lot and all the islands are volcanic. On the other hand… the quaking area is a stretch some 700 km long, this perhaps speaks clearly for a fault releaving stress.

    This is the map from today, and below it a broader view with North America on the west.

    http://www.cvarg.azores.gov.pt/civisa/Paginas/homeCIVISA.aspx

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  9. The PNG area is still taking a pounding from earthquakes .

    Some have stated on the internet whilst earthquakes are normal in this area the pounding PNG is taking from earthquakes at the moment is abnormal.

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    • Hi Janet, it is certainly true that the people living in PNG are abnormally harrassed by the constant shaking. If I were them (the source you cited), I would not use the terms normal – abnormal for geological events, though. We are looking only at a teeny weeny milli second of Earth’s life, and earthquake-wise, we can compare only with what we have experienced/measured a few tens or at best hundreds of years ago. How would we know what’s normal for an area, how many EQs happened there before recorded history? Maybe this time is absolutely un-normal with so few EQs? We don’t know. We just have to take things as they come and try to understand why they come. Perhaps some time in the future we may be able to even predict them.

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      • that shows the power of stastistics. There are a lot more events since a few weeks, but it is not at all linked. Albeit I have read of a greek publication talking about some tides’s influence. I have not read it. But Greece is one of the most active places, at least on Europe for quakes. So “We wonder, yess we wonder”.

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  10. Calbuco a few minutes ago:

    The reports from Sermageomin have not changed over the last days: volcano still in unstable condition, seismicity fluctuating, further eruptions possible, all restrictions and lahar warnings still in place.

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  12. Pingback: Volcanism along the Northern EPR 9.8° – 17° N |

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