DOI: 10.1016/j.tecto.2020.228688
论文题名: Tectonic regimes and stress patterns in the Vrancea Seismic Zone: Insights into intermediate-depth earthquake nests in locked collisional settings
作者: Petrescu L. ; Borleanu F. ; Radulian M. ; Ismail-Zadeh A. ; Maţenco L.
刊名: Tectonophysics
ISSN: 00401951
出版年: 2021
卷: 799 语种: 英语
中文关键词: Crust-mantle coupling
; Focal mechanisms
; Seismic nest
; Stress inversion
英文关键词: Anisotropy
; Faulting
; Seismic prospecting
; Dehydration embrittlements
; Earthquake generation mechanism
; Earthquake source parameters
; Intermediate depths
; Intermediate-depth earthquakes
; Lithospheric deformation
; Pore fluid pressure
; Unsupervised machine learning
; Earthquakes
; collision zone
; crust-mantle boundary
; deformation mechanism
; earthquake epicenter
; earthquake mechanism
; focal mechanism
; intraplate process
; lithospheric structure
; seismic anisotropy
; seismic source
; seismic tomography
; seismic zone
; seismicity
; source parameters
; stress field
; tectonic setting
; Carpathians
; Romania
英文摘要: Earthquake nests are anomalous clusters of seismicity located far from active collisional systems in intraplate, locked suture zones, or the deep part of relic subducted slabs, challenging classic earthquake generation mechanism theories. The Vrancea Seismic Zone in Romania is such an upper-mantle seismic nest located in the SE Carpathians, releasing the largest strain in continental Europe. To better understand earthquake generation and the relationship with lithospheric deformation, we estimate earthquake source parameters in Vrancea and surrounding regions between 2014 and 2020, and determine the stress field via focal mechanism inversion and unsupervised machine learning. In the crustal domain, maximum horizontal stress is in agreement with surface fault kinematics and GPS-derived S-SE trending horizontal plate velocities relative to Eurasia, implying that tectonic stress is vertically coherent on a crustal scale. The stress regime changes from transpression beneath the orogen to transtension towards the foreland where movement is accommodated along major crustal faults, and tension further away from the epicentre, in the Moesian Platform and the North Dobrogea Orogen. Inside the seismogenic body vertical tension and an overall compressive regime dominates, implying that vertical elongation may be the driving mechanism for brittle failure and that stress is transmitted along the sinking slab to the surface. However, the retrieved stress ratios are low: ~0.2 for mantle earthquakes Mw>4 and ~0.4 for Mw<4, challenging the brittle failure assumption. Increased pore fluid pressure has been shown to lower stress ratios, implying that dehydration embrittlement may contribute to generating intermediate-depth seismicity in the Vrancea slab. Comparisons with seismic tomography and anisotropy studies show excellent correlations between maximum horizontal stress directions, possible slab strike orientation, and seismic anisotropy, especially below ~130 km depth, suggesting ambient mantle flow may also promote in-slab stress build-up and seismic potential. © 2020 Elsevier B.V. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/170885
Appears in Collections: 气候变化与战略
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作者单位: National Institute for Earth Physics, Bucharest, Romania; Academy of Romanian Scientists, AcadCtists, Splaiul Independentei, 54, 050094, Bucharest, Romania; Karlsruhe Institute of Technology, AGW, Karlsruhe, Germany; Russian Academy of Sciences, IEPTMG, Moscow, Russian Federation; Utrecht University, Utrecht, Netherlands
Recommended Citation:
Petrescu L.,Borleanu F.,Radulian M.,et al. Tectonic regimes and stress patterns in the Vrancea Seismic Zone: Insights into intermediate-depth earthquake nests in locked collisional settings[J]. Tectonophysics,2021-01-01,799