scholarly journals Discriminating the Multi-Frequency Microwave Brightness Temperature Anomalies Relating to 2017 Mw 7.3 Sarpol Zahab (Iran-Iraq Border) Earthquake

2021 ◽  
Vol 9 ◽  
Author(s):  
Yifan Ding ◽  
Yuan Qi ◽  
Lixin Wu ◽  
Wenfei Mao ◽  
Yingjia Liu
Keyword(s):  
Brightness Temperature ◽  
Low Frequency ◽  
Satellite Orbit ◽  
Urmia Lake ◽  
Arabian Plate ◽  
Positive Anomaly ◽  
Eurasian Plate ◽  
Step Method ◽  
Microwave Brightness Temperature ◽  
Microwave Dielectric

A Mw 7.3 earthquake occurred near the Iran-Iraq border on November 12, 2017, as the result of oblique-thrust squeezing of the Eurasian plate and the Arabian plate. By employing the spatio-temporally weighted two-step method (STW-TSM) and microwave brightness temperature (MBT) data from AMSR-2 instrument on board Aqua satellite, this paper investigates carefully the spatiotemporal features of multi-frequency MBT anomalies relating to the earthquake. Soil moisture (SM), satellite cloud image, regional geological map and surface landcover data are utilized to discriminate the potential MBT anomalies revealed from STW-TSM. The low-frequency MBT residual images shows that positive anomalies mainly occurred in the mountainous Urmia lake and the plain region, which were 300 km north and 200 km southwest about to the epicenter, respectively. The north MBT anomaly firstly appeared 51 days before the mainshock and its magnitude increased over time with a maximum of about +40K. Then the anomaly disappeared 3 days before, reappeared 1d after and diminished completely 10 days after the mainshock. Meanwhile, the southwest MBT anomaly firstly occurred 18 days before and peaked 3 days before the mainshock with a maximum of about +20K, and then diminished gradually with aftershocks. It is speculated that the positive MBT anomaly in the Urmia lake was caused by microwave dielectric property change of water body due to gas bubbles leaking from the bottom of the lake disturbed by local crust stress alteration, while the southwest MBT positive anomaly was caused by microwave dielectric constant change of shallow surface due to accumulation of seismically-activated positive charges originated at deep crust. Besides, some accidental abnormal residual stripes existed in line with satellite orbit, which turned out to be periodic data errors of the satellite sensor. High-frequency MBT residual images exhibit some significant negative anomalies, including a narrow stripe pointing to the forthcoming epicenter, which were confirmed to be caused by synchronous altostratus clouds. This study is of guidance meaning for distinguishing non-seismic disturbances and identifying seismic MBT anomaly before, during and after some large earthquakes.

scholarly journals MINING SEISMIC THERMAL ANOMALIES FROM MASSIVE SATELLITE PASSIVE MICROWAVE IMAGES

2020 ◽  
Vol XLIII-B3-2020 ◽  
pp. 281-286
Author(s):  
Y. Qi ◽  
L. X. Wu ◽  
Y. F. Ding ◽  
M. He ◽  
W. F. Mao ◽  
...  
Keyword(s):  
Ground Surface ◽  
Thermal Anomaly ◽  
Passive Microwave ◽  
Step Method ◽  
Thermal Anomalies ◽  
Microwave Brightness Temperature ◽  
Microwave Dielectric ◽  
Evolution Characteristics ◽  
Large Earthquakes ◽  
Insight Into

Abstract. Satellite passive microwave radiative signals are considered to reflect thermal radiation and energy exchange of the Earth’s surface, and the microwave brightness temperature (MBT) has been preliminary adopted for pre-earthquake thermal anomaly monitoring in recent decades. Based on the spatio-temporally weighted two-step method (STW-TSM), this paper aims to uncover the evolution characteristics of MBT anomaly prior to typical earthquakes (EQs), i.e. the Mw7.9 Wenchuan EQ in May 2008, the Nepal EQs in April and May 2015, and the Mw5.8 Yibin EQ in June 2019, and to explore and recognize their differences and commonalities. The results are summarized as: 1) significant MBT positive anomalies appeared east and southwest close to the epicenter before the Wenchuan EQ, and the east anomaly migrated northeastward along Longmenshan faults with aftershocks, then the two anomalies dissipated subsequently with the ceasing of large aftershocks (Mw > 5.5). 2) the MBT positive anomalies of Nepal EQs firstly appeared along the Himalayas and became most obvious 1 day before the main shock, and dissipated subsequently after the first shock, and that of the second shock behaved in the same spatiotemporal patten. 3) regional positive MBT anomalies appeared around the epicenter a half month before the Yibin EQ and diminished over time, and the most obvious abnormal area transferred from the central and northwest to the southwest study area. It exhibited that MBT positive anomalies prefer to appear at the mechanically relaxed zones, such as the loose Quaternary with Wenchuan EQ, the cliff peaks with Nepal EQs, and the mountains surrounding Yibin EQ’s epicenter, which can be attributed to the declining of ground surface microwave dielectric caused by stress activated P-holes during the period of seismogenic preparation. This research provides a novel insight into mining MBT anomalies associate with large earthquakes and a possibility to explore the potential mechanism of such abnormal phenomena.

Influence of thermal treatments on the low frequency conductivity and microwave dielectric loss of CaTiO3 ceramics

2011 ◽  
Vol 176 (5) ◽  
pp. 401-405 ◽  
Author(s):  
Peng Hu ◽  
Huan Jiao ◽  
Chun-Hai Wang ◽  
Xiao-Ming Wang ◽  
Shi Ye ◽  
...  
Keyword(s):  
Dielectric Loss ◽  
Low Frequency ◽  
Thermal Treatments ◽  
Microwave Dielectric

scholarly journals Comparison of SMMR and SSM/I passive microwave data collected over Antarctica

1993 ◽  
Vol 17 ◽  
pp. 131-136 ◽  
Author(s):  
Kenneth C. Jezek ◽  
Carolyn J. Merry ◽  
Don J. Cavalieri
Keyword(s):  
Brightness Temperature ◽  
Microwave Radiometer ◽  
Correlated Data ◽  
Data Sets ◽  
Microwave Brightness Temperature ◽  
Brightness Temperatures ◽  
Scatter Plots ◽  
Microwave Imager ◽  
Highly Correlated ◽  
The Antarctic

Spaceborne data are becoming sufficiently extensive spatially and sufficiently lengthy over time to provide important gauges of global change. There is a potentially long record of microwave brightness temperature from NASA's Scanning Multichannel Microwave Radiometer (SMMR), followed by the Navy's Special Sensor Microwave Imager (SSM/I). Thus it is natural to combine data from successive satellite programs into a single, long record. To do this, we compare brightness temperature data collected during the brief overlap period (7 July-20 August 1987) of SMMR and SSM/I. Only data collected over the Antarctic ice sheet are used to limit spatial and temporal complications associated with the open ocean and sea ice. Linear regressions are computed from scatter plots of complementary pairs of channels from each sensor revealing highly correlated data sets, supporting the argument that there are important relative calibration differences between the two instruments. The calibration scheme was applied to a set of average monthly brightness temperatures for a sector of East Antarctica.

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