مشاهده‌ آنومالي در سري زماني هواويزها قبل از وقوع زلزله‌ هاي بزرگ با تصاوير موديس

Anomaly Observation in Aerosol Time Series before Large Earthquakes Using MODIS Satellite Images

زلزله يكي از مخرب‌ ترين سوانح طبيعي است كه پيش‌ بيني آن به‌ طور جامع، محقق نگشته است. به كمك داده‌ هاي سنجش از دور مي‌ توان به اطلاعاتي دسترسي پيدا كرد كه رابطه‌ ي نزديكي با وقوع زلزله دارند. اين اطلاعات همان پيش‌ نشانگرهاي زلزله هستند. ضخامت نوري هواويز (AOD) پارامتري است كه در اين مقاله به بررسي ارتباط آن با وقوع چند زلزله‌ ي بزرگ پرداخته مي‌ شود. پارامتر هواويز از طريق روش‌ هاي مختلفي مانند ايستگاه‌ هاي زميني شبكه‌ ي رباتيك هواويز و يا از طريق داده‌ هاي ماهواره‌ اي با به‌ كارگيري الگوريتم‌ هاي اهداف تيره (DDV)، روش SYNTAM و غيره به دست مي‌ آيد. با بررسي سري‌ هاي زماني AOD حاصل از محصولات سنجنده‌ ي موديس بر روي سكوي ترا، براي پنج زلزله‌ ي بزرگ در ايران، نابهنجاري‌ هايي قبل و بعد از وقوع زلزله مشاهده شد. نتايج نشان مي‌ دهند كه بين وقوع زلزله‌ هاي بزرگ و تغييرات غير عادي پارامتر ضخامت نوري هواويز رابطه‌ ي معناداري وجود دارد و ضخامت نوري هواويز به‌ عنوان يك پيش‌ نشانگر زلزله مي‌ تواند در تحقيقات بعدي مورد بررسي و مطالعه قرار گيرد.

An earthquake is a natural disaster that a lot of human and financial losses are results of that, and its prediction has not been materialized comprehensively. This damage can be prevented with earthquake prediction. The first successful prediction of large earthquakes was in 1975 that scientists could predict strong Haicheng earthquake in China. To date, different algorithms have been suggested to predict earthquakes, but there is not a unique algorithm that could be able to predict each earthquake around the world. Remote sensing data can be used to access information that is closely related to an earthquake called earthquake’s precursors. To date, various precursors were studied. The unusual variations of lithosphere, atmosphere and ionosphere parameters before the main earthquakes are considered as earthquake precursors. This paper examines one of the parameters which can be derived from satellite imagery. The mentioned parameter is Aerosol Optical Depth (AOD), and this article reviews its relationship with an earthquake. Aerosol Optical Depth (AOD) is one of the aerosol parameters that can give useful information about aerosols. Aerosols are small (sub-micron to several microns) suspend particles in the solid or liquid phase in the atmosphere. The main origins of aerosols are natural and anthropogenic. AOD in nature can be calculated by measuring the absorption of light at specific wavelengths of the visible spectrum. To use a wide variety of AOD, absorption at wavelength of 550 nm is recommended. Another way to obtain it is implementing different methods on satellite images such as AVHRR, MODIS, MISR, Sea WIFS, POLDER, TOMS, and MISR. However, it is a difficult task to achieve it, because solar lights are reflected by the atmosphere and the whole solar lights do not hit the ground. The most famous methods used to derive aerosol parameters are Dark Dense Vegetation (DDV) and SYNergy of Terra and Aqua MODIS (SYNTAM). DDV, which was presented by Kaufman in 1997, today is one of the most important algorit