Time Series Analysis on the Ratio for Pixels with Abnormal Brightness Temperature Increase and Its Variation Before Some Earthquakes with Ms ≥5.0 in the Taiwan Area

Abstract

In the study of application of MODIS satellite remote sensing data to earthquake prediction,the paper put forward for the first time a quantificational method for the ratio of the pixels with abnormal brightness temperature(BT)increasing and a preliminary scheme for cloud removal.The principle is that firstly,the cloudless data observed by the same satellite at the same period of time but in different days(usually 1 to 3 days)are mosaiched to get high cloudless rate data,and then the brightness temperature variation curve and mean variance of each pixel are calculated with the data from the covered area to determine daily whether the brightness temperature data of the day is normal or not at certain pixel by using twice of the mean variance as criterion.The ratio of the pixels with abnormal BT increasing can be calculated by dividing the total number of abnormal pixels with the total pixels of the whole area.Analysis on a series of recent earthquakes in Taiwan area shows that the ratio of pixels with abnormal BT increasing,which normally undulates around zero,had a sudden jump 1 to 20 days before the medium-strong earthquakes.It is expected that a new method for identifying earthquake auspice could be found through special studies in regions with frequent seismic activity by analyzing the change of ratio of the pixels with abnormal BT increasing from MODIS satellite remote sensing infrared information on which the effect of cloud has been removed to a certain extent.