Research progress of short period dense nodal array in deep crustal structure exploration

Because of its strong penetrating capability, the natural seismic receiving function has become the most widely used method for detecting crust-mantle structure. As the understanding of the structure and dynamic processes in the crust and upper mantle has advanced, the broadband seismic array with relatively large station spacing has become incompetent to the high-resolution imaging. The Dense Nodal Seismic Array (DNA), composed of hundreds of short-period portable digital high-frequency seismometers, offers a solution with station spacing as small as a few hundred meters, allowing for the collection of substantial observational data in a short time (1-2 months). Its advantages mainly include three aspects: (1) Good cross-ray-path coverage in the crust, conducive to improving imaging resolution; (2) Densely distributed ray-paths, facilitating noise suppression through coherent stacking of receiver functions, allowing for high-frequency receiver function imaging of crustal structures; (3) High efficiency due to the short observation time. Therefore, short-period dense array has become one of seismic observation approach commonly adopted in deep crustal structure research for only a few years. This paper mainly introduces the origin of short-period dense array in deep crustal structure exploration, and demonstrates its exploration effect and application in different tectonic domains through several typical exploration examples.