Investigation of the 2015 Ms5.8 Alxa Left Banner earthquake sequence: Aftershock evolution and seismogenic structure

Introduction: The 2015 M s 5.8 Alxa Left Banner earthquake (Alxa eathquake) struck a sparsely inhabited area of Inner Mongolia, northwestern China. However, as first > 5 event on the Ningxia–Inner Mongolia segment North–South seismic zone for 24 years, is considerable scientific interest. Methods: In this study, distribution sequence was redetermined via analysis data from permanent and campaign stations using double-difference (DD) method. To improve completeness catalog, match locate (M&L) method then used to detect micro-earthquakes. Results: mainshock rupture started at eastern end fault, propagating east-to-west deep-to-shallow. Aftershocks were distributed in NEE trending (N70°–75°E), with 12-km length dominant depth 15–25 km. Moreover, aftershocks formed two distinct segments (the western segments). early primarily located relatively fewer occurred segment. Discussion: Subsequently, March June 2016, three earthquakes L 3.0 gap between segments, releasing stress that not released by mainshock. According aftershock evolution, seismogenic fault eathquake associated NEE-striking blind becomes steeply dipping toward south. Furthermore, branch Dengkou–Benjing (DBF). evolution inferred structure provide reference further research study area.