S069-04
Receiver function analysis from a dense nodal array: Delineating shallow crustal structure from local and teleseismic receiver function analysis
Receiver function analysis from a dense nodal array: Delineating shallow crustal structure from local and teleseismic receiver function analysis
Thursday, 17 December 2020: 04:14
Virtual
Abstract:
Traditional receiver function (RF) analysis applied to broadband station data is widely used for investigating the Moho and other deep mantle and crustal structures. RFs can also delineate shallow crustal structure (e.g. basin scale) which however requires high-frequency events and can be further facilitated through dense recording arrays.
In 2019, 130 Fairfield 3C ZLand nodes were deployed in Cushing (Oklahoma, US) to monitor and image a shallow basement fault. The nodes were deployed along county roads with the dense spacing of 150 m to 250 m in a grid-like fashion. 12 teleseismic events and 28 local events are used in the receiver function analysis. Benefiting from the dense array deployment, we interpret higher frequency teleseismic RFs (3 Hz) which appear as sharp Moho and intracrustal conversions. In addition, shallow sediment reverberation and multiples can be better distinguished from the noise.
Furthermore, our study investigates the feasibility of using local seismic events (epicentral distances < 250 km) for RF analysis. Those events have the advantage of high frequencies (3 to 10 Hz) which significantly improves imaging for shallow structures. In the Cushing area, the basement is expected in a depth of ca. 1 km, well beyond the resolution capability of teleseismic events. In contrast, the local events allow to image this shallow basement.
Local RF analysis and interpretation is challenged by relatively large incidence angles, potential cross-talk between vertical and horizontal components, and interference with shallow P-wave multiples. We address these issues with numerical modeling and conclude that local RF analysis can be useful for densely spaced arrays.
In 2019, 130 Fairfield 3C ZLand nodes were deployed in Cushing (Oklahoma, US) to monitor and image a shallow basement fault. The nodes were deployed along county roads with the dense spacing of 150 m to 250 m in a grid-like fashion. 12 teleseismic events and 28 local events are used in the receiver function analysis. Benefiting from the dense array deployment, we interpret higher frequency teleseismic RFs (3 Hz) which appear as sharp Moho and intracrustal conversions. In addition, shallow sediment reverberation and multiples can be better distinguished from the noise.
Furthermore, our study investigates the feasibility of using local seismic events (epicentral distances < 250 km) for RF analysis. Those events have the advantage of high frequencies (3 to 10 Hz) which significantly improves imaging for shallow structures. In the Cushing area, the basement is expected in a depth of ca. 1 km, well beyond the resolution capability of teleseismic events. In contrast, the local events allow to image this shallow basement.
Local RF analysis and interpretation is challenged by relatively large incidence angles, potential cross-talk between vertical and horizontal components, and interference with shallow P-wave multiples. We address these issues with numerical modeling and conclude that local RF analysis can be useful for densely spaced arrays.