حرکات تکتونیک جنبا یا فرونشست های ناشی از سوبسیدانس مقاله

محققان در سه دهه اخیر تلاش گسترده ای را برای روشن ساختن علل بوجود آمدن ترک های دشت های رسوبی آغاز و غالباً ایجاد چنین شکاف هایی را به برداشت بیش از حد آب های زیر زمینی نسبت داده اند . اگرچه فرونشست در این دشت ها به اعتبار اسناد معتبر علمی امری اثبات شده است ولی نسبت دادن آن به برداشت آب از سفره های زیر زمینی با تردیدهایی همراه بوده است، زیرا پدیده "شق" یا "درام " برای بسیاری از دهقانان ایرانی قبل از بکارگیری تکنولوژی مکنده های دیزلی وحفرچاه های عمیق پدیده ای شناخته شده بوده است. از طرفی فرونشست تنها به دشت هایی با بیلان منفی محدود نشده و دشت هایی با بیلان مثبت را هم شامل می شود. این شواهد سبب شد که برای روشن شدن علت این موضوع به اتکا دو روش مختلف اسنادی و مدل سازی تجربی ازسفره زیرزمینی در دو حالت دینامیک و استاتیک عملا به رصد رفتار این گونه دشت ها در برابر برداشت آب از سفره ها و تحرکات تکتونیکی مبادرت شود. نتایج حاصل از این تحقیق نشان می دهد که : * پدیده شق یا درام که غالب محققان آنرا به برداشت بی رویه از سفره های آبی زیرزمینی نسبت می دهند دارای سابقه تاریخی بسیار طولانی تری است به گونه ای که این پدیده قبل از رایج شدن تکنولوژی مکنده های دیزلی و حفر چاه های عمیق برای بسیاری از دهقانان ایرانی پدیده تجربه شده وشناخته شده ای بوده است.

In the last three decades, researchers have begun a wide-ranging effort to elucidate the causes of sedimentary cracks in the plains and have often attributed such gaps to excessive groundwater harvesting. Although subsidence in these plains has been proven credible by scientific documents, its relevance to water abstraction from underground aquifers has been subject to some uncertainty, as the "shag" or "drum" phenomenon has been pre-empted by many Iranian peasants. The adoption of diesel suction technology and deep wells has been a well-known phenomenon. On the other hand, subsidence is not confined to low-negative plains and positive-low plains. This evidence led to the observation of the behavior of these plains in terms of water abstraction from aquifers and tectonic motions to clarify the cause of this issue by relying on different types of documents and empirical modeling of the underground in both dynamic and static conditions. The results of this study show that: * The phenomenon of drumming or drumming, which most scholars attribute to the overwhelming harvest of underground aquifers, has a much longer historical history, so that this phenomenon before many diesel diggers and digging wells for many Iranian peasants. The phenomenon has been experienced and recognized.In the last three decades, researchers have begun a wide-ranging effort to elucidate the causes of sedimentary cracks in the plains and have often attributed such gaps to excessive groundwater harvesting. Although subsidence in these plains has been proven credible by scientific documents, its relevance to water abstraction from underground aquifers has been subject to some uncertainty, as the "shag" or "drum" phenomenon has been pre-empted by many Iranian peasants. The adoption of diesel suction technology and deep wells has been a well-known phenomenon. On the other hand, subsidence is not confined to low-negative plains and positive-low plains. This evidence led to the observation of the behavior of these plains in terms of water abstraction from aquifers and tectonic motions to clarify the cause of this issue by relying on different types of documents and empirical modeling of the underground in both dynamic and static conditions. The results of this study show that: * The phenomenon of drumming or drumming, which most scholars attribute to the overwhelming harvest of underground aquifers, has a much longer historical history, so that this phenomenon before many diesel diggers and digging wells for many Iranian peasants. The phenomenon has been experienced and recognized.In the last three decades, researchers have begun a wide-ranging effort to elucidate the causes of sedimentary cracks in the plains and have often attributed such gaps to excessive groundwater harvesting. Although subsidence in these plains has been proven credible by scientific documents, its relevance to water abstraction from underground aquifers has been subject to some uncertainty, as the "shag" or "drum" phenomenon has been pre-empted by many Iranian peasants. The adoption of diesel suction technology and deep wells has been a well-known phenomenon. On the other hand, subsidence is not confined to low-negative plains and positive-low plains. This evidence led to the observation of the behavior of these plains in terms of water abstraction from aquifers and tectonic motions to clarify the cause of this issue by relying on different types of documents and empirical modeling of the underground in both dynamic and static conditions. The results of this study show that: * The phenomenon of drumming or drumming, which most scholars attribute to the overwhelming harvest of underground aquifers, has a much longer historical history, so that this phenomenon before many diesel diggers and digging wells for many Iranian peasants. The phenomenon has been experienced and recognized.In the last three decades, researchers have begun a wide-ranging effort to elucidate the causes of sedimentary cracks in the plains and have often attributed such gaps to excessive groundwater harvesting. Although subsidence in these plains has been proven credible by scientific documents, its relevance to water abstraction from underground aquifers has been subject to some uncertainty, as the "shag" or "drum" phenomenon has been pre-empted by many Iranian peasants. The adoption of diesel suction technology and deep wells has been a well-known phenomenon. On the other hand, subsidence is not confined to low-negative plains and positive-low plains. This evidence led to the observation of the behavior of these plains in terms of water abstraction from aquifers and tectonic motions to clarify the cause of this issue by relying on different types of documents and empirical modeling of the underground in both dynamic and static conditions. The results of this study show that: * The phenomenon of drumming or drumming, which most scholars attribute to the overwhelming harvest of underground aquifers, has a much longer historical history, so that this phenomenon before many diesel diggers and digging wells for many Iranian peasants. The phenomenon has been experienced and recognized.

ــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــ 1 lofgren 2 Allen 3 Gabrysch 4 Poland 5 Leak 6 Edelman 7 Jennings 8 Esmely 9 Cook and Dorncomp هدف از اين پژوهش که بر گرفته از يک روش استنادي ۱ وازمايشگاهي تجربي است بيشتر معطوف به آزمون نظريات ارائه شده در مورد مکانيسم وعلت بوجودامدن پيامدهاي شکل شناسي پديده سوبسيدانس بوده است وسعي شده با اتکا به عملکرد دو مدل استاتيک ۲ وديناميک ۳ چنين رفتاري تبيين گردد . الف : سفره آبي استاتيک در زميني به مساحت ۷۵۵۰ سانتي متر مربع و با لايه هاي مختلف رسي ، لايه ماسه اي آبدار، لايه ماسه و رس کف ايجاد گرديد و امکان تزريق آب به سفره و پمپاژه آن توسط يک موتور کوچک الکتريکي فراهم آمد پس از تزريق آب و اشباع سفره آبدار به تخليه آرام آب در فواصل زماني مشخص اقدام و تغييرات سطح زمين که در اثر افت سطح آب در سفره به وجود مي آمد، رصد گرديد. (به تصویر صفحه مراجعه شود) شکل شماره ۱۱: نمايش شکافهاي برداشت شده از تصاويردر مدل ديناميک با توجه به نتايج وگزاره هاي بدست آمده ميتوان مدعي شد که آزمايش هاي تجربي در ميکرو مدل هاي دست ساخت نمي تواند نظرات ان دسته از محققان که برداشت بي رويه آب از سفره هاي زير زميني را علت تامه فرونشست دانسته اند تاييد نمايد وآنچه تحت عنوان شکاف هاي ناشي از سوبسيدانس دانسته ميشود بيشتر معطوف به حرکات تکتونيک جنباست که پورخسرواني اين حرکات را دوال و ايزوستازي نرم نامگذاري کرده است .