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Earthquake - Image of the fault line image..not comforting

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  • #16
    Re: Earthquake - Image of the fault line image..not comforting

    <span style="font-family: 'Arial Black'">Ancient, pre-historic of Jamaica</span>
    <span style="font-style: italic">published: Thursday | March 20, 2008</span>

    <span style="font-style: italic">Mona Institute of Applied Sciences (MIAS), Eye on Science, Palaeoseismology, Contributor</span>


    <span style="font-style: italic">St Thomas plains (foreground) with mountains in the background. The Plantain Garden Fault lies within the mid-ground of this photo.</span>

    In science there are a number of words that begin with the prefix palaeo- (English) or paleo- (North American) such as palaeomagnetism, palaeontology, palaeoclimate, and paleoseismology. Synonyms of palaeo- are old, ancient and pre-historic. Palaeoseismology is the science of finding past earthquakes, the art of literally uncovering when and where ancient earthquakes occurred and the likely magnitudes of the events.

    Given the late 20th-century surge in instrumental detection, recording and analysis of earthquakes, and remote-sensing methods, it is interesting that seismology had to revert to basic arduous and dirty geological field work, albeit with a difference, for some of the most pertinent discoveries on earthquake recurrence and seismic hazard, which indeed no modern seismogram can disclose. Emerging only in the last 20 or so years of the 20th century the scientists who specialise in such work are palaeoseismologists, essentially geologists trained to look for ancient earthquakes in the walls of trenches dug across or along fault lines.

    <span style="font-family: 'Arial Black'">The first step</span>


    <span style="font-style: italic">Trench exposing sediments across a terrace riser at Serge Island.</span>

    The first step in any palaeoseismic study involves searching for suitable places to dig. Digging is expensive in cost and time, and not possible nor practical everywhere along the fault. It is therefore worth the time and effort to study the area very carefully using small scale maps, aerial photographs, Google Earth and even fly-overs in light aircraft or by helicopter, anything that gives a good view of the terrain and helps to narrow the search for prospective successful trench sites. What exactly is one looking for? Faults when they move, particularly in larger earthquakes, offset topographic and riverine features like spurs and ridges and river terraces, creating risers and notches and other distortions of the land. Once these features exist at the surface, the underlying layers should show corresponding disruptions. Geologists infer what the subsurface looks like by mapping rock types and attitudes at the surface. Palaeoseismologists conduct digs, much like archaeologists, to expose relics of fault activity. Dating of carbon samples and sediments taken from the trench are used to constrain the age of the deformation and hence the time of occurrence of the earthquake(s). The record of movements can cover hundreds to tens of thousands of years, well beyond the historical records, and the recurrence of large earthquakes can usually be demonstrated. Trenching can also target secondary features of large earthquakes, such as sand blows and lateral spreads caused by liquefaction, that may be preserved in the sediments and are not directly on the fault. Trenching can reveal the frequency of tsunamis. At low tide, on the tidal flats of Patagonia, Chile trenches a mere four feet deep show vast deposits of sand that was scooped off the sea floor during the 1960 tsunami caused by the world's largest known earthquake, and repeated events going back a thousand years.

    In January, a team of earth scientists from the universities of Texas, Wisconsin and the West Indies, the United States Geological Survey and the Petroleum Corporation of Jamaica conducted the first palaeoseismic studies along Jamaica's south coast and Plantain Garden Faults. These faults are probable sources of Jamaica's earliest and largest known earthquake, that of June 7, 1692, that wrecked the city of Port Royal never to be rebuilt. So little is known about the source of that event that the goal of the study was to look for evidence of that and other major earthquakes predating 1692. The search began at the National Land Agency on Charles Street to obtain maps and aerial photos, continued at the Mines and Geology Division and the Department of Geography and Geology, all of which have those resources. Along the way there were useful discussions with other Jamaican geologists. The staff at all these agencies were very helpful in assisting us to find the material needed. The first week was spent tracking the south coast fault from Salt River, Clarendon west to Kemp's Hill, Round Hill, Canoe Valley to Alligator Pond, Manchester and Port Kaiser in St Elizabeth. A number of features were noted in the vicinity of Round Hill and the cane fields to the east, but the sediments were still saturated with the island just coming out of the prolonged wet season at the end of 2007, so no trenching was attempted, possibly postponed for a later date. So the focus shifted to St Thomas and back to the various agencies to get the relevant maps and air photos.

    <span style="font-family: 'Arial Black'">Site search</span>


    <span style="font-style: italic">Trench on the east arm of the Morant River showing possible fault or a splay.</span>

    The search for sites led to the Serge Island Dairy Farms, an abandoned pasture where a number of river terraces and risers were plain to see. The first trench was dug courtesy of the company who allowed us to use their backhoe for a day. Disappointed that the trenches dug on the farm revealed no relict fault processes, the team moved on to the east arm of the Morant River in the vicinity of the village of Hillside following a flyover of the fault from Morant Bay to Morant Point afforded us by the JDF air wing. Two trenches were dug at this locality using a rented backhoe across what appeared to be the trace or a splay (like a tributary is to a river) of the PGF. Samples of carbon and other sediments were sent for dating and obvious offsets of sediments were noted. Time constraints of team members precluded proper mapping and logging of the trench and trenching at other selected sites. All trenches were back filled with the material removed.

    Trenching in Jamaica remains a study to be continued. What happens next will depend on the results of dating the samples collected, the availability of funds and time of the team members, particularly the palaeoseismologist. Other faults on the island worthy of investigation include the Duanvale, Crawle River, Wagwater, Silver Hill, Spur Tree, Santa Cruz and Montpelier faults. Currently, only 316 years of earthquake history for Jamaica is known and this holds just one earthquakes of magnitude greater than seven and two greater than six, not enough to forecast recurrence trends of these damaging events, and what the future might bring. Palaeoseismology could recover perhaps 1,000 years or 10,000 years of earthquake history which when combined with slip rates measured using Global Positioning System and knowledge of current seismicity could provide conclusive results regarding Jamaica's seismic past and future. Members of the team were in alphabetical order, Ms Bryn Benford (PhD student), Dr Charles DeMets (Geophysicist), Omar Josephs (Geologist), Will King (Geology student), Dr Paul Mann (Geologist), Dr Carol Prentice (Palaeoseismologist) and Dr Margaret Wiggins-Grandison (Seismologist).

    Margaret D. Wiggins-Grandison, PhD, research fellow/seismologist

    Address: Earthquake Unit, 2 Plymouth Crescent, University of the West Indies - Mona campus, Kingston 7

    Telephone: (876) 927-2586/935-8249; fax: (876) 977-3575

    email: [email protected].

    <span style="font-family: 'Arial Black'">The MIAS</span>

    The MIAS is a non-profit organisation of the University of the West Indies, Pure and Applied Sciences Department, offering analytical, technical and, web services and specialised science projects. If you have any questions or comments about these articles please email : [email protected] or contact the MIAS Analytical Services Division at 970-2042 or 512-3067 for enquires on services offered.
    <span style="font-weight: bold">0ok</span>

    <span style="font-style: italic">&quot;What good fortune for those in power that people do not think&quot;</span>
    - <span style="font-weight: bold">Adolf Hitler</span>, as quoted by Joachim Fest.

    Comment


    • #17
      Re: Earthquake - Image of the fault line image..not comfort

      sistactry yu knoo wen da fault line release da pressure on part aff de fault line itt increase de likeleewood aff earth quake sumwear else alang da fault line


      still mii doan worry bout ting mii cyaan cantrol. addarwise mii wood affii worree bout asteriods crashinn inna earth, black holes, solar flares inn 2012, life aftah peeps.........etc
      I have no desire to take all black people back to Africa; there are blacks who are no good here and will likewise be no good there.
      Marcus Garvey

      satire protected speech soo more fiyah

      Comment


      • #18
        Re: Earthquake - Image of the fault line image..not comfort

        sobering.

        no offense to everyone but way more than prayers are going to be needed.

        almost makes sense to keep a few large ships well equipped to handle disaster relief, with helicopters, at sea. even though all this relief is getting there and en route, the port is severely damaged- the cranes toppled, etc. at least jamaica has several possible landing sites. and if set up appropriately the ships can disburse aid without having to make use of standard ports.
        a noble stroke he lifted high that hung not but swift with tempest fell On Satan's proud crest- no sight nor swift thought, less could his shield such ruin intercept; 10 paces huge he back recoil'd...

        Comment


        • #19
          Re: Earthquake - Image of the fault line image..not comfort

          <div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: monk</div><div class="ubbcode-body">almost makes sense to keep a few large ships well equipped to handle disaster relief</div></div>

          Two days ago James Moss Solomon was on Nationwide Radio. He sounded mad as hell as he recounted how he had proposed just a solution to regional Governments based upon the Western Caribbean Nations ever looming threat of catastrophic destruction from natural disasters.

          Of course <span style="font-family: 'Arial Black'">reason</span> and <span style="font-family: 'Arial Black'">science</span> faces an uphill struggle when dealing with bible thumpers and inept leaders.
          <span style="font-weight: bold">0ok</span>

          <span style="font-style: italic">&quot;What good fortune for those in power that people do not think&quot;</span>
          - <span style="font-weight: bold">Adolf Hitler</span>, as quoted by Joachim Fest.

          Comment


          • #20
            Re: Earthquake - Image of the fault line image..not comfort

            a true u a talk me breddah, any ting can happen anytime~~
            “Those who know your name will trust in you, for you LORD, have never forsaken those who seek you” (Psalm 9:10)

            Comment


            • #21
              Re: Earthquake - Image of the fault line image..not comforting

              You know how it is already. that is why they hide a lot of facts from the majority of people.
              The planet is covered by lots of broken plates.
              They float on it's molten iron core, and due to the spin of the planet,the gravitational interaction cause them to be forced on each other.
              Ther is a long rift in the pacific, thatis getting deeper.

              and ther is a long submerged mountain in the Atlantic that is getting higher.
              So in the fyuture the may be a mountain range from the Puerto Rico To Green Land amd the Atlantic will be divided, by this vast land mass.
              But we won't even know this.
              Since we will be all gone by then.
              So no reason to worry.
              Haiti had such devastation because it has been kept too poor to build proper housing for it's people.
              Jamaica is almost ther for the same reason.
              countries have been forced into poverty, by developed countries.
              That catastrophe is one of the effects .
              <div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: SistaCtry</div><div class="ubbcode-body">Doc, all this talk bout fault line and plate, a mek nuff ppl nervous ehh?? </div></div>
              Join me as members of the church of LOVE,and let us change the world, one good deed at a time.

              Comment


              • #22
                Re: Earthquake - Image of the fault line image..not comforting

                <div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Dr.Dudd</div><div class="ubbcode-body">You know how it is already. that is why they hide a lot of facts from the majority of people.
                The planet is covered by lots of broken plates.</div></div>

                <span style="font-family: 'Arial Black'">BS </span>no one is hiding anything as a child by the time I reached High School in Jamaica we had been told where the fault lines were suspected to be not only in Jamaica but all across North America and Mexico.
                High School first year Geography would have rounded out the total picture.
                <span style="font-weight: bold">0ok</span>

                <span style="font-style: italic">&quot;What good fortune for those in power that people do not think&quot;</span>
                - <span style="font-weight: bold">Adolf Hitler</span>, as quoted by Joachim Fest.

                Comment


                • #23
                  Re: Earthquake - Image of the fault line image..not comfort

                  <span style="font-style: italic">Why would anyone think this info is hidden?
                  </span>
                  This is all common knowledge ...

                  I learned all about plate tectonics by the time I was 12 years old.

                  <div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Tuff Gong</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Dr.Dudd</div><div class="ubbcode-body">You know how it is already. that is why they hide a lot of facts from the majority of people.
                  The planet is covered by lots of broken plates.</div></div>

                  <span style="font-family: 'Arial Black'">BS </span>no one is hiding anything as a child by the time I reached High School in Jamaica we had been told where the fault lines were suspected to be not only in Jamaica but all across North America and Mexico.
                  High School first year Geography would have rounded out the total picture. </div></div>

                  Comment


                  • #24
                    Re: Earthquake - Image of the fault line image..not comfort

                    <div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Yuri_</div><div class="ubbcode-body"><span style="font-style: italic">Why would anyone think this info is hidden?
                    </span></div></div>

                    <span style="font-family: 'Arial Black'">Serial liars</span> will write and say anything ....you just never know.
                    I thought they needed volunteer Doctors in Haiti, especially ones with Haitian experience?
                    <span style="font-weight: bold">0ok</span>

                    <span style="font-style: italic">&quot;What good fortune for those in power that people do not think&quot;</span>
                    - <span style="font-weight: bold">Adolf Hitler</span>, as quoted by Joachim Fest.

                    Comment


                    • #25
                      Re: Earthquake - Image of the fault line image..not comfort

                      BOADWL aye sah
                      R Kelly all summer long *sigh* <<GRAEMLIN_URL>>/inlove1.gif

                      Comment


                      • #26
                        Re: Earthquake - Image of the fault line image..not comfort

                        Anyway, jamaica had its earthquake back in 16 sitten or nedda...mi sure smaddy else will come chat bout Port Royal.

                        When a jamaica time, is jamaica time...
                        R Kelly all summer long *sigh* <<GRAEMLIN_URL>>/inlove1.gif

                        Comment


                        • #27
                          Re: Earthquake - Image of the fault line image..not comfort

                          mi SEH

                          dah chread yah sweet mi suh till
                          “Not all those who wander are lost.” –J. R. R. Tolkien

                          What if you took your life back....LIVE like you MEAN IT~~~~~FL

                          Comment


                          • #28
                            Re: Earthquake - Image of the fault line image..not comfort

                            enuh

                            first form geography



                            <div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Yuri_</div><div class="ubbcode-body"><span style="font-style: italic">Why would anyone think this info is hidden?
                            </span>
                            This is all common knowledge ...

                            I learned all about plate tectonics by the time I was 12 years old.

                            <div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Tuff Gong</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Dr.Dudd</div><div class="ubbcode-body">You know how it is already. that is why they hide a lot of facts from the majority of people.
                            The planet is covered by lots of broken plates.</div></div>

                            <span style="font-family: 'Arial Black'">BS </span>no one is hiding anything as a child by the time I reached High School in Jamaica we had been told where the fault lines were suspected to be not only in Jamaica but all across North America and Mexico.
                            High School first year Geography would have rounded out the total picture. </div></div> </div></div>
                            “Not all those who wander are lost.” –J. R. R. Tolkien

                            What if you took your life back....LIVE like you MEAN IT~~~~~FL

                            Comment


                            • #29
                              Re: Earthquake - Image of the fault line image..not comfort

                              <div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: BiziBubbla</div><div class="ubbcode-body">Anyway, jamaica had its earthquake back in 16 sitten or nedda...mi sure smaddy else will come chat bout Port Royal.

                              When a jamaica time, is jamaica time... </div></div>nuh jus 1908 dem did have the earthquake?
                              When its hot in the jungle of peace I go swimming in the ocean of love.....

                              Comment


                              • #30
                                Re: Earthquake - Image of the fault line image..not comforting

                                <div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Dr.Dudd</div><div class="ubbcode-body">
                                Haiti had such devastation because it has been kept too poor to build proper housing for it's people. </div></div>

                                agree. it was a strong earthquake, but the extent of the devastation had to do with the quality of buildings, density, the social more than the scientific factors, imo. similar situation with the last earthquake in china, where so many kids were killed while they were in shoddily built school buildings.
                                <span style="font-style: italic">All Glory to The Hypnotoad!</span>

                                Comment

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