Space Geodetic Observations and Modeling of 2016 Mw 5.9 Menyuan Earthquake: Implications on Seismogenic Tectonic Motion

Abstract

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.

Geo-Hazard Detection and Monitoring Using SAR and Optical Images in a Snow-Covered Area: The Menyuan (China) Test Site

“…Since 1927, more than five earthquakes with M S > 6 have occurred within a 100-km range from the epicenter of the Menyuan earthquake, according to the U.S. Geological Survey (USGS). The largest one, with a magnitude of MS 8.0, occurred in May 1927, and the next largest earthquake with a magnitude of MS 6.5 occurred on 26 August 1986 [19]. The easternmost Qilian Mountain called Lenglongling, which is a famous geological fault belt, reflects all the characteristics and essence of the Qilian Mountains; the detailed tectonic background can be found in Reference [19].…”

“…The largest one, with a magnitude of MS 8.0, occurred in May 1927, and the next largest earthquake with a magnitude of MS 6.5 occurred on 26 August 1986 [19]. The easternmost Qilian Mountain called Lenglongling, which is a famous geological fault belt, reflects all the characteristics and essence of the Qilian Mountains; the detailed tectonic background can be found in Reference [19]. The peak of Lenglongling, known as "Gangshika", a tourist attraction, is 5254.5 m above sea level.…”

“…Figure 3 shows the differential interferogram generated with the Sentinel-1A images acquired on 18 January 2016 and 11 February 2016. More than two fringes can be clearly interpreted, and an unwrapped phase shows a maximum uplift of about 16 rad (see Figure 5), which corresponds to about 7 cm in the radar line of sight direction, and more detailed deformation information caused by this earthquake can be found in References [19,26]. Apart from the large area of deformation caused by the earthquake, small fringe patterns can be clearly seen in the earthquake deformation area (some of them are marked with black arrows in Figure 3).…”

Rapid rupture directivity determination of moderate dip‐slip earthquakes with teleseismic body waves assuming reduced finite source approximation

“…Thus, the mainshock rupture is inferred to start near the surface and proceed downward, consistent with previous teleseismic waveform studies [ Vogfjord and Langston , ]. In addition to aftershocks and foreshocks, interferometric synthetic aperture radar (InSAR) data provide valuable evidence in defining the epicentral location and fault plane for moderate earthquakes via ground displacement modeling, such as the 1998 M w 5.7 Zhangbei earthquake, the 2009 M w 6.3 L'Aquila earthquake, and the 2016 M w 5.9 Menyuan earthquake [ Li et al , ; Guerrieri et al , ; Li et al , ].…”

Earth Observations for Geohazards: Present and Future Challenges

“…InSAR observations are utilised to investigate the 2003-2004 Bange, China earthquake sequence, involving a series of normal faulting events with Mw > 5.0, indicating that InSAR can provide reliable source parameters of shallow, moderate-sized earthquakes in areas that lack dense seismic networks [13]. Li et al [14] use Sentinel-1A interferograms to model the 2016 Mw 5.9 Menyuan, China earthquake; they find that the 2016 event has a different focal mechanism from a previous Ms 6.5 earthquake although both are at the two ends of a secondary fault, which is believed to reflect the left-lateral strike-slip characteristics of the Lenglongling fault zone. Multi-platform InSAR observations are employed to determine the coseismic and postseismic slip distributions of the 2011 Mw 7.1 Van, Turkey earthquake, indicating that the upper 7-9 km of the fault, unruptured during the coseismic phase, underwent afterslip in the postseismic phase that may have reduced the seismic potential in its whole length from NW to SE [15].…”