Eruptions


Al-Qider volcano in western Saudi Arabia. Image courtesy of Ahmed Al-Hussaini.

After a week’s worth of worry, it appears that the seismicity in western Saudi Arabia is subsiding. The latest statement from Zuhair Nawab, the head of the SGS, is that over the past four days with fewer and less severe aftershocks. If this continues, people who have evacuated the area around Al Ais might be able to return to their homes in a few days. However, it is important to note that even though officials suggest the seismicity is waning (and there may be indications this is not entirely accurate), the swarm is definitely not “over”.

Rumors/reports of increased radon gas and changes in the chemistry of the well waters near the earthquakes epicenters appear to be unfounded. Saad al Mohlafi, the deputy director of the National Observation Centre, said that “no gases indicating an imminent eruption of a volcano have been found in Alees [Al-Ais].” This contradicts a lot of what was being said earlier last week and would support the idea that these earthquakes might not be directly related to any imminent eruption from Harrat Lunayyir. However, this does not preclude the idea that these earthquake could have been the product of a subvolcanic intrusion of magma underneath the volcano field that did not lead to an eruption. These contradictory reports and rumors have lead to more confusion for the residents of the region.

I am still flabbergasted by comments like this from Zuhair Nawab: “The magma level is still at eight kilometres … I don’t know where the media got this worrying level from.” I have yet to find any information about how the SGS (a) knows what depth there might be melt – i.e., magma and (b) what “magma level” even means. The article linked here (and above) from The National in Abu Dhabi does suffer from a lot of mish-mashed science, such as bring up that, according to the EPA, radon “is reportedly the second-most frequent cause of lung cancer, after cigarette smoking.” How does this help our understanding of any potential precursors to eruption? It really doesn’t, but it does give an false pretense of scientific authority to the article.

I’ll keep an eye on how events might change in western Saudi Arabia – remember, just because seismicity seems to be waning now doesn’t mean this won’t change in the near future. In any case, these earthquakes were a fascinating study in how rumor can effect people’s perceptions of the perceived volcanic danger. If another earthquake swarm were to begin in the next months or years, the reaction might be very different.

Comments

  1. #1 megan
    May 26, 2009

    How does this connect with the seismic activity that recently happened in California, 4point something. All of the plates connect and sent shock waves through the earth’s core and mantles apart from touching each other. Is there a planetary model that predicts and shows the stress points of the globe and where reverberating shocks might show up days weeks later across the globe?

  2. #2 Thomas Donlon
    May 26, 2009

    Megan,

    I’ve seen a report of a study that a 7 earthquake can cause heightened seismic activity at the other side of the world for a few hours. But the strength of the earthquakes in Saudi Arabia weren’t stronger than the typical earthquakes that occur each day. Five magnitude quakes occur on most days somewhere in the world. Some days it might be in the Andes, other days they occur in Indonesia or maybe Kamchatka. Sometimes they occur in Alaska or Europe, or the mid-Atlantic ocean. Volcanic earthquakes are not usually strong.

  3. #3 Perry Debell
    May 27, 2009

    Today’s Seismic Monitor indicates a strong earthquake in Saudi Arabia Wed May 27 10:10:08 GMT 2009

    http://www.iris.edu/seismon/bigmap/index.phtml

  4. #4 robert somerville
    May 27, 2009

    thats weird, neither Iris or
    “European-Mediterranean Seismological Centre”;
    http://www.emsc-csem.org/index.php?page=home ,
    show any now 10:40 May 27( UTC )

  5. #5 Chris
    May 27, 2009

    I see nothing on the USGS web site. There was an earthquake in Iran today. Are you confusing this with Saudi Arabia?

  6. #6 Perry Debell
    May 28, 2009

    My apologies. You guys are right and I am so wrong. I did not apply map reading skills and jumped on the flashing red circle in Iran. Be thankful I am not an airline pilot, otherwise we would now be propaganda I am so mortified that I could not distinguish between the Red Sea and the Persian Gulf.

    Today, it’s the eastern Pacific Rim that is active.

  7. #7 robert somerville
    May 28, 2009

    apparently not the first time this area has scared the Saudis:
    http://www.arabnews.com/?page=1&section=0&article=102500&d=16&m=10&y=2007

  8. #8 megan
    May 28, 2009

    Is this connected as to deeper earth magma and plate movements and shockwaves bouncing?

    [[ 7.1 earthquake topples homes in Honduras, Belize (AP)
    AP - A strong earthquake killed at least one man early Thursday as it collapsed homes in Honduras and Belize and sent people running into the streets in their pajamas as far away as Guatemala City. ]]

  9. #9 Thomas Donlon
    May 29, 2009

    http://www.a1saudiarabia.com/Return-of-tremor-evacuees-postponed/

    Article states, “AL-EIS – Civil Defense officials have postponed the return of evacuees to their homes in Al-Eis and the villages of Omluj until next week after light tremors were felt in the region on Wednesday. Tremors occurred early Wednesday afternoon, with the strongest two recorded at 2.6 and 2.2 on the Richter scale, shortly after the Saudi Geological Survey (SGS) had published its daily report saying that no tremors of over three on the Richter scale had been registered in the previous 24 hours. A Civil Defense official said Wednesday that the return of evacuees would now not take place until after Saturday. – Okaz/SG”

  10. #10 Hank Roberts
    May 29, 2009

    > How does this connect …?
    > Is this connected …?

    Short answer: through the planet, yes, slightly.

    Megan, you probably can get a pointer from one of the scientists about research on connection between quakes far apart. There have been some papers published recently showing slightly more small quakes than expected, even at large distances, during a short time after some large quakes.

    That’s a small signal emerging from a high background noise level — detected in the past few years. Like much else in science, correlation and statistical work were needed to show there is something there. Details? Maybe someone who knows something about it will give you a pointer.

    Try the experiment at home. On the largest table in the house, make a lot of little piles of salt or sand by pouring it out of a small funnel or paper cone, so you have a whole lot of little conical piles. Each will be at the angle of repose for the material.

    Kick one leg of the table. How many of them collapse?

    Elaborate this — make a grid on the table, or use a sewing table cover (preprinted, like graph paper but table size, for those who don’t know).

    Put one of the little cones of material in each square. Kick the table leg. Is there a pattern to which ones collapse?

    Elaborate again — take some pepper, some salt, and some cumin or other spice. Make up three combinations of varying proportions. Throw a die to decide which of your three mixes goes in each square randomly. Kick the table leg.

    My guess — the other table legs will either transfer more of the shaking or stabilize the piles over them. The varying mixes will have different angles of repose.

    Dampen some of the material before making cones; does that make them more or less likely to collapse?

    Lots of variables, far more than this suggests. Yes, one very large remote quake may slightly increase, for a brief period of time, the chance of something nearby, but there’s much more going on.

    We know there will be another earthquake. The rest is probabilities.

  11. #11 robert somerville
    June 1, 2009

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