DOI: 10.1016/j.epsl.2017.11.049
Scopus记录号: 2-s2.0-85040788100
论文题名: Active backstop faults in the Mentawai region of Sumatra, Indonesia, revealed by teleseismic broadband waveform modeling
作者: Wang X. ; Bradley K.E. ; Wei S. ; Wu W.
刊名: Earth and Planetary Science Letters
ISSN: 0012821X
出版年: 2018
卷: 483 起始页码: 29
结束页码: 38
语种: 英语
英文关键词: backstop
; backthrust
; fault geometry
; focal mechanism
; Sumatra
; waveform modeling
Scopus关键词: Earthquakes
; Fault slips
; Geometry
; Geophysics
; Location
; Structural geology
; Surface waves
; Waveform analysis
; backstop
; backthrust
; Fault geometry
; Focal mechanism
; Sumatra
; Waveform modeling
; Faulting
; active fault
; broadband data
; fault geometry
; focal mechanism
; modeling
; teleseismic wave
; thrust
; waveform analysis
; Indonesia
; Mentawai Islands
; Sumatra
; West Sumatra
英文摘要: Two earthquake sequences that affected the Mentawai islands offshore of central Sumatra in 2005 (Mw 6.9) and 2009 (Mw 6.7) have been highlighted as evidence for active backthrusting of the Sumatran accretionary wedge. However, the geometry of the activated fault planes is not well resolved due to large uncertainties in the locations of the mainshocks and aftershocks. We refine the locations and focal mechanisms of medium size events (Mw > 4.5) of these two earthquake sequences through broadband waveform modeling. In addition to modeling the depth-phases for accurate centroid depths, we use teleseismic surface wave cross-correlation to precisely relocate the relative horizontal locations of the earthquakes. The refined catalog shows that the 2005 and 2009 “backthrust” sequences in Mentawai region actually occurred on steeply (∼60 degrees) landward-dipping faults (Masilo Fault Zone) that intersect the Sunda megathrust beneath the deepest part of the forearc basin, contradicting previous studies that inferred slip on a shallowly seaward-dipping backthrust. Static slip inversion on the newly-proposed fault fits the coseismic GPS offsets for the 2009 mainshock equally well as previous studies, but with a slip distribution more consistent with the mainshock centroid depth (∼20 km) constrained from teleseismic waveform inversion. Rupture of such steeply dipping reverse faults within the forearc crust is rare along the Sumatra–Java margin. We interpret these earthquakes as ‘unsticking’ of the Sumatran accretionary wedge along a backstop fault separating imbricated material from the stronger Sunda lithosphere. Alternatively, the reverse faults may have originated as pre-Miocene normal faults of the extended continental crust of the western Sunda margin. Our waveform modeling approach can be used to further refine global earthquake catalogs in order to clarify the geometries of active faults. © 2017 The Authors Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/110086
Appears in Collections: 影响、适应和脆弱性 气候变化事实与影响
There are no files associated with this item.
作者单位: Earth Observatory of Singapore, Nanyang Technological University, Singapore; Asian School of the Environment, Nanyang Technological University, Singapore; Department of Geosciences, Princeton University, United States
Recommended Citation:
Wang X.,Bradley K.E.,Wei S.,et al. Active backstop faults in the Mentawai region of Sumatra, Indonesia, revealed by teleseismic broadband waveform modeling[J]. Earth and Planetary Science Letters,2018-01-01,483