28 comments on “Halmahera: JAILOLO EARTHQUAKE SWARMS – volcanic or tectonic?

  1. reminds me of the swarm at Matata that was long thought to be just tectonic (it’s on the western edge of the Whakatane graben) but was later found to be caused by a sill developing.
    http://www.radionz.co.nz/news/national/305592/magma-buildup-blamed-for-quakes

    M5 seems very large though and strike-slip also doesn’t sound too much like a sill forming. Given the bizarre tectonic environment, there may be something else happening like a transform fault developing or something.
    OTOH the depth does seem to be relatively constant over the entire length of the sequence.
    Very intriguing!

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  2. Nicely done, Guys. Gut reaction is we are seeing a magma chamber being charged. Probably completely wrong. Sure would like to see a low velocity zone map of the region. Half expecting to see something interesting.

    Given the jumbled tectonics of the surrounding area, I wonder what they resolve to. In other words, what happens over the millions of years to such a jumbled region? Western Antarctica started out as 4 – 5 microplates jostling one another, but there is very little tectonic movement and they kind of froze into place. E of Sulawesi moves a lot as it is being squeezed from all sides, primarily from the south via the Australian Plate on its way north to China. What a mess. What a fascinating mess. Cheers –

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  3. Whoa, the geology of the spot seems really very complex.

    Plus the data is hard to come by – for instance only one quake show for the Agung area (just in case you’d ask -:) )
    Thanks to Granyia for pointing me out to the catalog. Unfortunalety this is not iceland or Spain and data is not as complete, there are only the higher intensity quakes.

    Please be indulgent this is my first shot while using Python, as my previous Octave/Matlab scripts do not work anymore because of an obscure graph engine problems in Linux.

    I’ll try to better the plot system in the weeks to come, but I’m travelling for work right now, so it’s not easy.

    Cheers and thanks for a great article (I’ll need some time to digest it)

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  4. Plus I see some paywalled article – if you want them I have a way to get them, most of the time, just say

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    • I have only difficulties (sometimes) finding very new papers of, say, the last week or so. Otherwise I use http://sci-hub.cc/, which is also pretty good and can deliver most of the papers, even pre-releases. – Also, a new browser extension has been developed earlier this year – Unpaywall – but I find it not being very effective yet. Perhaps it needs some more time becoming known to authors and building up a good database. http://unpaywall.org/. Thank you for offering help!

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      • I know of the first one, but there are others.

        Meanwhile in La Palma….

        As the pythoncode is done it is relatelively easy to adapt.

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        • Now this is one neat intrusion, coming up straight from depth as one would expect! Is this when the swarm began, early October, or just the time when the bulk of the quakes appeared? Most of them at 20-25 km deep, way to go. But that most shallow one came up last, so the dike is still progressing upwards. Thank you, dfm, and keep at it!

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          • Hi Granyia

            it’s since the beginning of October.
            Neat intrusion, but nothing to fear for the moment we will see what happens next.
            I’ll try to perfect the code as we go. I’ll probably do some updates if there are some new developments.

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  5. Nature paper on volcanic impact on Nile flooding over the last 2400 years. Despite the headlines blaming this on Russian, Alaskan and Greenland volcanoes, I could find no specific volcanoes mentioned. At first glance, looks like the work is based on models, ice core data, and a record of Nile water levels called the Nilometer. Link to actual paper follows. Cheers –

    https://www.nature.com/articles/s41467-017-00957-y

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  6. First tornillos and HT starting to show up on the Agung plot. Still very sporadic but a good sign that magma is getting shallow enough for bubbles to start forming in it and allow resonance to occur in the conduit(s)/dykes (he says, sounding like he knows what he is talking about but doesn’t) 😉

    Has anyone heard of any recent inflation data?

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  7. For comparison:
    Left: GEarth image of Agung crater from 03/08/2014
    Right: One of the first 400 images of a drone flight over crater on 2017/10/19. The crack in the E part (left side) reportedly widened. – Both images enhanced (sharpness, contrast) by me. To be honest, I can’t spot the cracks…

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  8. The Bali Expat reports that today a decision was expected on whether or not to downgrade the alert level from 4 to 3, based on declining seismicity. But no announcement has come through in the media so far, and it’s past midnight in ID now.

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          • Yeah, that’s what it is, you can wait for the earthquakes coming in when you see it pouring on the webcams. I remember when Ubinas’ activity started a few years ago, they said, oh, it’s nothing, just rainwater causing little steam explosions, don’t worry. Ubinas has had some sizeable ashy phreatic eruptions in the following months and years.

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  9. Even the rough Ggl-translation makes it clear that there must have been a harsh discussion in Bali over the alert status of G. Agung. Mr. Kasbani (PVMBG/ESDM) confirmed that the status of Gunung Agung remains at Level IV (Awas).

    He said in a press conference today: Our institution will not be rushed to change the status of Mount Agung, because the volcano’s activity is still high and fluctuating. Although currently the seismicity shows a decrease compared with previous days, the deformation data still show the opposite, i.e. there is still inflation. This means that this is not the right time to reduce the status of Mount Agung. We still have to watch its development, if all parameters show consistent slow decline, including the deformation, and when also the visual observation activities have decreased, it can be our guide to decrease the status of G. Agung. That means, the status is not made by me but by the information we get from the mountain itself.

    Well spoken!

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    • Good on him! I really don’t envy volcanologists in that position. there are no doubt huge pressures on them to reduce no-go zones when an “imminent” eruption decides to take its time and people feel their lives are being unduly disrupted.
      But only going on the signs we can see (the seismogram, the fumaroles, and the reports of inflation) it most definitely looks like magma has risen to shallow levels and this development is on the back of a long and sustained intrusion. It certainly hasn’t stopped yet and certainly has the potential to culminate in a life-threatening eruption. Just because the last eruption started with lava flows before ramping up into an explosive eruption doesn’t mean it is going to do the same again this time.

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      • PS there is much more pronounced gas and fluid activity on the seismogram in the last 7 hours.

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        • Plus, there are so many other factors in a seismic record, for one example that in some volcanoes earthquakes cease altogether shortly before an eruption.

          But, as to the small noise (“thickening” of the lines) I believe that could be human activity as it begins abt. 8 am and diminishes after abt. 7pm. Don’t know if wind plays a role as well, depends how sensitive the sensor is.

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  10. Another volcano (that unanimously “roared to life” in various newspapers) erupted in the Solomon Islands yesterday: Tinakula is a 3.5-km-wide, now uninhabited island at the NW end of the Santa Cruz island group – and the exposed top of a large andesitic stratovolcano. It produced an 11 km high ash plume (acc. to Wellington VAAC) yesterday. More ash advisories have been issued since, so the eruption seems to continue.

    The volcano sent black ash into nearby communities when it started erupting early Saturday morning, and authorities do not have a scientific way to monitor the situation and determine when it will end (SIBC, 22/10). – Tinakula is described to closely resemble Stromboli volcano as it has a breached summit crater, forming a scree slope from the summit to below sea level. Last activity was in 2012.


    The northern side of Tinakula volcano.
    (Image: GSSI, courtesy of CSIRO)


    Tinakula: White patches of steam/gas (‘vapour trails’) were caused by red-hot boulders bouncing down the slope. (observation by Cook and others in 2012, via GVP).

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    • Howdy Granyia –

      I remember seeing fumaroles on the flanks of Pinatubo in Jan 1979.

      There were post eruption fumaroles in the crater around the crater lake following the eruption. Don’t know how their activity has declined over time. Will poke around a bit and see if I can find more current photos. Cheers –

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  11. This must be the study which the press had hyped up about a few weeks ago, and Erik wrote a blog post to straighten things out.

    Probing Magma Reservoirs to Improve Volcano Forecasts … using the Yellowstone plateau as an example, we review current understanding of magma storage regions as relevant to volcanic hazards. We focus on two popular techniques for characterizing magma reservoirs, one geophysical (seismic tomography) and the other petrological (geospeedometry). We then suggest a third option—scientific drilling—that has the potential to dramatically improve our understanding of magma dynamics…” – Highly interesting read!

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  12. sustained tremor now on the Agung plot. there is a rain shower going through so it might just be water entering the system and boiling.

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