Abstract
Determining the relationship between crustal movement and faulting in thrust belts is essential for understanding the growth of geological structures and addressing the proposed models of a potential earthquake hazard. A Mw 5.9 earthquake occurred on 21 January 2016 in Menyuan, NE Qinghai Tibetan plateau. We combined satellite interferometry from Sentinel-1A Terrain Observation with Progressive Scans (TOPS) images, historical earthquake records, aftershock relocations and geological data to determine fault seismogenic structural geometry and its relationship with the Lenglongling faults. The results indicate that the reverse slip of the 2016 earthquake is distributed on a southwest dipping shovel-shaped fault segment. The main shock rupture was initiated at the deeper part of the fault plane. The focal mechanism of the 2016 earthquake is quite different from that of a previous Ms 6.5 earthquake which occurred in 1986. Both earthquakes occurred at the two ends of a secondary fault. Joint analysis of the 1986 and 2016 earthquakes and aftershocks distribution of the 2016 event reveals an intense connection with the tectonic deformation of the Lenglongling faults. Both earthquakes resulted from the left-lateral strike-slip of the Lenglongling fault zone and showed distinct focal mechanism characteristics. Under the shearing influence, the normal component is formed at the releasing bend of the western end of the secondary fault for the left-order alignment of the fault zone, while the thrust component is formed at the restraining bend of the east end for the right-order alignment of the fault zone. Seismic activity of this region suggests that the left-lateral strike-slip of the Lenglongling fault zone plays a significant role in adjustment of the tectonic deformation in the NE Tibetan plateau.
Highlights
A Mw 5.9 earthquake struck the Menyuan county, Qinghai (101.641 ̋ E, 37.67 ̋ N) on 21 January2016
Both earthquakes resulted from the left-lateral strike-slip of the Lenglongling fault zone and showed distinct focal mechanism characteristics
The normal component is formed at the releasing bend of the western end of the secondary fault for the left-order alignment of the fault zone, while the thrust component is formed at the restraining bend of the east end for the right-order alignment of the fault zone
Summary
A Mw 5.9 earthquake struck the Menyuan county, Qinghai (101.641 ̋ E, 37.67 ̋ N) on 21 January. Great activity behavior of the Lenglongling main fault and the focal mechanisms of two earthquakes (1986 differences in mechanical properties [4], which indicates the complexity of the tectonic stress field and and 2016). Joint analysis with the 1986 Menyuan earthquake, and the background and fault will be analyzed to reveal the tectonic relationship between the seismogenic fault and the main mechanical properties of the seismogenic fault will be analyzed to reveal the tectonic relationship fault of Lenglongling zone. It will enhance our understanding of the implications on seismogenic between the seismogenic fault and the main fault of Lenglongling zone. Both ends of the secondary fault of Lenglongling are bent to converge to the main fault
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