Abstract
On 9 July 2009, an Ms6.0 earthquake occurred in mountainous area of Yao’an in Yunnan province of Southern China. Although the magnitude of the earthquake was moderate, it attracted the attention of many Earth scientists because of its threat to the safety of the population and its harm to the local economy. However, the source parameters remain poorly understood due to the sparse distribution of seismic and GNSS (Global Navigation Satellite System) stations in this mountainous region. Therefore, in this study, the two L-band ALOS (Advanced Land Observing Satellite-1) PALSAR (Phased Array type L-band Synthetic Aperture Radar) images from an ascending track is used to investigate the coseismic deformation field, and further determine the location, fault geometry and slip distribution of the earthquake. The results show that the Yao’an earthquake was a strike-slip event with a down-dip slip component. The slip mainly occurred at depths of 3–8 km, with a maximum slip of approximately 70 cm at a depth of 6 km, which is shallower than the reported focal depth of ~10 km. An analysis of the seismic activity and tectonics of the Yao’an area reveals that the 9 July 2009 Yao’an earthquake was the result of regional stress accumulation, which eventually led to the rupture of the northwestern most part of the Maweijing fault.
Highlights
An Ms6.0 earthquake occurred in Yao’an of Yunnan province of Southern China on 9 July 2009
Cao and Mao investigated the characteristics of the earthquake precursors and macroscopic anomalies and suggested that the Yao’an earthquake corresponds well to the tectonic background of frequent earthquakes in Yunnan province [7]
The 2009 Ms6.0 Yao’an earthquake occurred along the Maweiqing fault, which is located on southwestern Yunnan block, parallel to the Red River fault [6]
Summary
An Ms6.0 earthquake occurred in Yao’an of Yunnan province of Southern China on 9 July 2009. The Earth’s structure of the Yao’an region has been studied, such as the three-dimensional velocity structure of the source [2], gravity changes before the earthquake [3], deep structures [4], seismic surface wave velocity [5], and earthquake precursors and macroscopic anomalies [7]. These investigations revealed preliminary geometric features and underground structures of the earthquake. The characteristics of the earthquake derived from InSAR inversion are discussed along with the results of geological and geophysical, Coulomb stress modeling, and the regional tectonics of frequent earthquakes in Yao’an area studies
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