1. Mick West

    Mick West Administrator Staff Member

    Apocalyptic sounding headlines have accompanied this story about a large crack in the Earth in Mexico.

    20140823-113430-o4id7.

    Firstly is seems almost certain that this is nothing at all to do with earthquake activity, as many headlines have suggested. The earth has not simply "split open", as the ground on both side of the crack has stayed exactly where it started. We can see here that the fence posts have not moved, instead the ground has been removed from underneath.

    [​IMG]

    Instead, as you can partially see from what looks like a muddy stream in the top image, the culprit is water, as was somewhat explained in the Mexican press.

    http://www.excelsior.com.mx/nacional/2014/08/21/977513
    There actually seems to be two things going on here:
    1. A subsidence fissure, where irrigation caused wet areas of the region to pull away from dry areas due to differential compaction, leading to a narrow but deep fissure.
    2. Gully erosion, where heavy water flow, likely from rain, rapidly eroded the fissure into the shape we see above. This may happen long after the original fissure has formed.

    The crack is in a region of newly constructed irrigation ditches and ponds, and recent heavy rains had saturated the ground. The translation from the Spanish scientists suggests some kind of underground flow creating the crack. Certainly there has been some flow erosion. But the initial cause of the fissure seems more likely to be differential compaction. Differences in irrigation, or water extraction, combined with differences in the level of the underground bedrock, creates differences in compaction and rates of settling, eventually causing fissures, often partially or fully underground. These fissures then grow rapidly as water flows though them. It's not that uncommon, and these type of fissure have been well studied here in the US, particularly in Arizona, as in this USGS page:
    http://water.usgs.gov/edu/gallery/landsubsidence-lakelucern.html
    [​IMG]

    And there's a detailed explanation in this white paper from the Arizona Land Subsidence Group
    http://azgs.az.gov/Earth Fissures/CR-07-C.pdf
    [​IMG]
    [​IMG]

    The sudden widening of the fissure coincided with heavy rains in August, as reported on local TV. This image is from roughly the same general area. Heavy summer rains and flooding are very common in the Sonora region.
    [​IMG]

    And this was the flooding August 18th 2014, in Carborca, about 100 miles to the north of the fissure.
    http://www.elimparcial.com/EdicionE...an-Carretera-de-la-Muerte-por-inundacion.html
    [​IMG]

    And it's not something limited to the desert. Heavy rain on a steep hillside in the UK led to very similar looking cracks earlier this year. In this case the trigger was not thought to be a fissure, but something like a rabbit burrow that allowed the rain to get a start:
    http://www.dailymail.co.uk/news/art...ld-without-crops-prior-heavy-winter-rain.html
    [​IMG]

    Another misconception in the press is the location of the crack, as typified here:
    http://www.news.com.au/technology/e...earthquake-fears/story-e6frflp0-1227032868718
    And the Daily Mail:
    http://www.dailymail.co.uk/news/art...splits-earth-open-rural-northwest-Mexico.html
    Now that would be very significant, as highway 26 is a major route in the region, a paved two lane highway. However, in the image above all we can see is a dirt road. And if we go to the source, we see there's been a bit of a mistranslation somewhere.

    http://www.excelsior.com.mx/nacional/2014/08/21/977513
    The problem here is that La Candelaria is a very small town that does not show up on Google maps, so it seem that by a process of Chinese whispers, the road became Hwy 26, and the town became Hermosillo.

    Geolocating photos is an interesting challenge, so I though I'd have a go at this one. Starting with this photo of the crack from the drone footage:
    [​IMG]

    This proved a little tricky, as the fields are new, and don't show up in Google Earth. But I was eventually able to track it down by knowing which road it was on, and by looking at the pattern of brush. In particular there's four small bushes in a line just south of the road, to the right of center. And then on the other side there's four larger bushes in a line leading up to the small mound of rocks.
    20140823-123638-icigc.
    With this, I was able to find the precise location of the crack.
    20140823-115845-9alsa.
    [​IMG]
    I've attached a Google Earth .kmz file with this overlay and location.
     

    Attached Files:

    Last edited: Aug 24, 2014
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  2. solrey

    solrey Senior Member

    [Admin: The following post was created independently of the above at about the same time, and has been merged here to avoid duplicate discussion threads]

    A large Earth Fissure was recently created in the Costa de la Hermosillo region of Sonora, Mexico. True to form, dutchsinse has claimed he predicted "major movement" in the area and the crack is his confirmation (bias). The truth is something else entirely. The region is in the Sonoran Desert, very arid and heavily irrigated. Over pumping of the aquifer has been an issue throughout the Sonoran Desert for decades, which leads to subsidence which can create earth fissures especially after heavy rains. This has been confirmed to be the case by a geologist from the Universidad de Sonora so I thought I'd post this debunk since his video has nearly 200,000 views... and honestly, he earned it.

    youtube.com/watch?v=MmS3dhGISHU&list=UUHE92x768p8h-fMrqhsnE1Q

    I tried to tell dutchsinse that the fissure was consistent with subsidence before it was confirmed by a geologist. His response:

    *It's been over 48 hours and so far... NADA*

    Grieta means crack/crevice/fissure, whereas a geological fault in spanish is falla. A couple of the articles mention earthquake as a metaphor, as in the crack appeared "as if it had been the result of an earthquake". None of them say anything about soon expecting any sort of quake. What they're saying is the crack occurred after heavy rains, as stated in one of his own links. :rolleyes:

    Since then the geologist from the Universidad de Sonora has summarily discounted the idea that an earthquake or "major movement" created the fissure and confirmed it was indeed caused by subsidence and groundwater intrusion, vindicating my "water hypothesis". According to the geologist the fissure begins at a small dam under construction for agricultural purposes. Heavy rains infiltrated what was likely a small subsidence induced crack, undercutting the surface where it collapsed to create a large earth fissure.

    http://www.excelsior.com.mx/nacional/2014/08/21/977513

    https://translate.google.com/translate?hl=en&sl=auto&tl=en&u=http://www.excelsior.com.mx/nacional/2014/08/21/977513

    A good concise explanation of earth fissures:

    http://cwanamaker.hubpages.com/hub/Geologic-Hazards-What-You-Need-to-Know-About-Earth-Fissures

    More info on earth fissure and aquifer depletion:

    http://geology.utah.gov/utahgeo/hazards/ground_cracks/fissures.htm

    http://ag.arizona.edu/oals/IALC/sonoran/documents/nabhan/db_groundwater.html

    http://www.sciencedirect.com/science/article/pii/S0167564808705367

    http://link.springer.com/article/10.1007/s100400050172#page-1

    http://enviro.doe.gov.my/lib/digital/1386315252-1-s2.0-S0167564808705367-main.pdf

    http://link.springer.com/article/10.1186/2194-6434-1-7/fulltext.html
     
    Last edited by a moderator: Aug 26, 2014
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  3. Mackdog

    Mackdog Active Member

    There was also a huge sinkhole that opened up under the national corvette museum in Louisville Kentucky back in February, caused by a collapse sinkhole that happened to be right under the museum. This is due to this area being in a karst landscape. Different than the one in New Mexico because the N.M. fissure was caused by water leaving the sub-surface and the sinkhole in kentucky as caused by too much water washing through the sub-surface. Actually went and visited the museum last week and took some pics. I think people that spread theories like this just don't want to look at how many other places in the world experience similar incidents. IMG_0644.JPG IMG_0647.JPG
     
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  4. Jason

    Jason Senior Member

    NASA developed remote sensing technology to hopefully predict 'sink holes'.
     
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  5. Mackdog

    Mackdog Active Member

    I'll have to read more about that new sensor. I'm actually studying remote sensing right now as part of my degree (Geography/GIS). I did an internship this past summer with NASA and got to work with a variety of remotely sensed data from JPL as part of a project to study California forest fires and using hyper-spectral imagery to assess post fire vegetation loss. I'm not surprised that they have the ability to detect ground elevation changes via satellite..also they are using more UAV's to monitor small areas of the earth such as farm fields and damage caused by earthquakes and mudslides. A few years ago, I played at a golf course pretty close to this museum, around mammoth cave in southern Kentucky and there were many subsistence sinkholes (depressions in the ground) on that course because of all of the caves underneath the area. You could see the ground starting to give way..I'm just surprised that there are not more sinkholes that form in this area, like under Interstate 65 or other major roads in the area.
     
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  6. Mackdog

    Mackdog Active Member

    This is also a good video about the Floridian aquifer. Most people don't know that Florida has a vast underground system of dive-able caves that are also the drinking water aquifer for many people in Florida. They are under threat of pollution and contamination and are also the cause of many sinkholes in Florida.

     
  7. WeedWhacker

    WeedWhacker Senior Member

    VERY interesting, thanks! Although I am SCUBA-certified, seems I have a slight irrational fear ('phobia') in the open ocean ('OW')!! (Figures....it would "show-up" after I did all my training!).

    Here's an article that I found:
    http://divermag.com/fear-diving-phobias-afraid-of-scuba-diving/

    I suppose this is veering well off-topic, but the mention of under-sea aquifers, and sinkholes (related to the thread OP) just fired in my brain.
     
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  8. vooke

    vooke Active Member

    Informative thread, but the point was fully made by the second image showing the fencing intact
     
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  9. Jeff D

    Jeff D New Member

    The Mexican scientist referenced early on also stated that there was no difference in the ground level on either side of the fissure. The pictures show this as well. There was no general subsidence on either side, only directly above the water flow. It can be seen that the soil at the bottom of the ditch is still darkened with moister and obvious signs of water flow but there is no evidence of water entering from surface rain water runoff. An article in Saturdays El Imparcial

    http://www.elimparcial.com/EdicionE.../877719-Explican-posible-causa-de-grieta.html

    states that, in addition to the aforementioned subsidence, a nearby well or wells were old and had been infiltrated with sand and that sand had been pumped from the well. This is how the fissure formed. The sand, and water, near the well collapsed and got sucked in first. As ground water moved to the well it dislodged more sand a little further from the well and the soil above that dislodged sand collapsed down into the water table and it all got liquefied and suck into the pump also. This process continues farther and farther away from the well until the base of the gully meets the top of the water table and there is no more flow of water to dislodge any more sand. This is why the gully tapers down the farther it goes until all that is visible is a narrow crack on the surface. Notice that there is no differential subsidence in the area where the gully tapers down to a mere surface crack. The only subsidence was directly above the flow of water to the well. If the well had only let water leach in and not allowed sand to also enter the sand would not have been dislodged and no gully would have formed.
     
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  10. mythlyn

    mythlyn New Member

    I am so glad i logged onto this site already seeing in my facebook the sky is falling and that this was in new mexico on the border. Thank you so much
     
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  11. Mackdog

    Mackdog Active Member

    As a side note, there are actually places where the Earths crust really is splitting apart and separating, though it has been an ongoing process for millions of years. For example, the basin and range province of the western United States (Nevada and parts of Utah and California) is an area where this is occurring. http://geography.about.com/od/physicalgeography/a/basinrange.htm

    Basin&Range_shad_GTOP_1.JPG


    Also the Arabian peninsula and the surrounding Red Sea and Persian Gulf is an example of where parts of the earth are sinking below other parts, because of crustal separation. The low parts in this case are filled with sea water over time and become gulfs or seas. These blocks of earth that either sink or rise are called Horst and Graben. The ones that rise are basically mountain ranges, and the ones that sink are either a desert playa or a sea.

    Horst_Graben_1.24b.
     
    Last edited: Aug 30, 2014
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  12. derrick06

    derrick06 Active Member

    This was a great article! Thanks for clearing up the geography behind this. It's foolish how the media and the net gets pumped with speculation instead of actually inspecting what the likely causes are. Especially since nothing "split." but a collapse. Good stuff as always @Mick West always something great to learn on here :)
     
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