Source Complexity of the 2015 Mw 7.9 Bonin Earthquake

作者：Chen, Yu^*; Meng, Lingsen; Zhang, Ailin; Wen, Lianxing

来源：Geochemistry Geophysics Geosystems, 2018, 19(7): 2109-2120.

DOI：10.1029/2018GC007489

• deep earthquake
• source complexity
• back-projection
• multiple-source inversion
• slab heterogeneity

The 30 May 2015 Mw 7.9 Bonin earthquake, one of the largest and deepest earthquakes ever recorded by modern seismology, provides a unique opportunity to study the source process and physical mechanisms of deep-focus earthquakes. We develop a novel back projection technique that allows source imaging in full three-dimensional space with a high-depth resolution. Our results indicate an initial SW-NE bilateral source propagation followed by a northwest source extension. The multiple-source inversion reveals a two-step source process with propagating directions nearly perpendicular to each other, consistent with the 3-D back projection result. The spatial distribution and focal mechanisms of the subevents cannot be modeled by a single planar rupture, which may display a curved rupture plane or subevents crossing multiple fault interfaces. The complex source process can be best explained by stress or structure heterogeneity within the deep slab. @@@ Plain Language Summary We utilize a 3-D back projection method and multiple-source inversion method. We find that the Bonin earthquake does not rupture on a planar fault plane. Instead, the earthquake process can be best explained by rupture on a curved fault plane or subevents crossing multiple fault interfaces. The variation of spatial distribution and focal mechanisms may indicate the slab heterogeneity.

• 出版日期2018-7
• 单位中国科学技术大学