Abstract
Thermal anomalies related to large earthquakes are frequently reported, but focus on the inconsistencies and uncertainties in the uncovered results caused by the diverse method used, data used, and case studies is lacking. Taking seismic anomaly detection using passive microwave remote sensing as an example, this study revealed and illustrated the time series of microwave brightness temperature (MBT) anomaly associated with the May 2008 Wenchuan earthquake, the April 2010 Yushu earthquake, the April 2013 Lushan earthquake, and the April and May 2015 Nepal earthquake sequence. Cross comparison showed that the spatial distribution of MBT anomalies behaves differently with different background-removal methods. More regional and detailed MBT anomalies (but with weaker intensities) were obtained with higher frequency data, whereas more pronounced MBT anomalies (but with fewer details) were acquired with lower frequency data. The amplitude and spatial scales of MBT anomalies at H polarization were larger than that at V polarization. And 10.7 GHz at H polarization was recommended as the optimal band. The spatiotemporal evolutions of MBT anomalies associated with the four selected earthquake cases were compared and found to be closely related to respective earthquake preparation mechanisms. The aforementioned characteristics and uncertainties of MBT anomalies under different conditions were then discriminated and discussed based on microwave remote-sensing physics, and the applications and limitations of the present study were illustrated and analyzed. The findings of this study are of great significance for remote sensing data selection, reliability assessment, and result interpretation in seismic-anomaly research.
Highlights
Since the 1980s, satellite infrared radiative data have been applied to detect multitemporal thermal anomaly prior to some medium-to-strong earthquakes [1]-[13]
Maeda and Takano [15], [16] proposed an anomaly index algorithm based on temperature difference between adjacent pixels to monitor seismic anomaly associated with the February 2004 Morocco earthquake and the May 2008 Wenchuan earthquake using microwave brightness temperature (MBT) data with 18.7 GHz from the Advanced Microwave Scanning Radiometer for EOS (AMSR-E) instrument, and found that significant anomalies occurred near the mainshock epicenters
Jing et al [19] analyzed thermal anomalies associated with two earthquakes that occurred at the Tibetan Plateau by using segmented threshold method with Sensor Microwave/Imager (SSM/I) MBT data; it was found that MBT at 19 GHz was more sensitive to seismic anomalies than other higher frequencies
Summary
Since the 1980s, satellite infrared radiative data have been applied to detect multitemporal thermal anomaly prior to some medium-to-strong earthquakes [1]-[13]. Jing et al [19] analyzed thermal anomalies associated with two earthquakes that occurred at the Tibetan Plateau by using segmented threshold method with SSM/I MBT data; it was found that MBT at 19 GHz was more sensitive to seismic anomalies than other higher frequencies. These case studies confirm that multitemporal MBT data with multiple frequency can retrieve seismic anomaly. Owing to the different research methods used, the results for different frequencies and for different cases are not comparable; the spatiotemporal pattern of seismic anomaly under different conditions and the reasons for discrepant results require further consideration
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
