DOI: 10.1016/j.tecto.2021.228854
论文题名: Why do continental normal fault earthquakes have smaller maximum magnitudes?
作者: Neely J.S. ; Stein S.
刊名: Tectonophysics
ISSN: 00401951
出版年: 2021
卷: 809 语种: 英语
中文关键词: Continental earthquakes
; Maximum magnitude
; Normal fault earthquakes
英文关键词: Earthquakes
; Geometry
; Yield stress
; Centroid moment tensors
; Classification criterion
; Earthquake magnitudes
; Laboratory studies
; Maximum magnitudes
; Probability calculations
; Stress difference
; Subduction zones
; Fault slips
; continental lithosphere
; earthquake magnitude
; fault geometry
; frequency-magnitude distribution
; moment tensor
; normal fault
; rupture
; seismic hazard
英文摘要: Continental normal fault earthquakes have been reported to have smaller maximum magnitudes (Mmax) than continental earthquakes with other fault geometries. This difference has significant implications for understanding seismic hazards in extensional regions. Using the Global Centroid Moment Tensor (GCMT) catalog, we examine how Mmax varies with fault geometry in continental regions, whether these trends are robust, and potential physical reasons for the smaller magnitudes of continental normal fault earthquakes. We find that the largest continental normal fault earthquakes are in the low Mw 7 range whereas other fault geometries can reach ~Mw 8. The continental normal fault earthquake magnitude-frequency distribution has a lower corner magnitude (a parameterization of Mmax) than other fault geometries. The observed smaller continental normal fault Mmax is not an artifact of classification criteria or catalog length. Probability calculations indicate that the GCMT catalog is long enough to capture differences in Mmax due to fault geometry. Additionally, our analysis indicates that neither fault length nor width is limiting the size of continental normal fault earthquakes. Fault complexity can limit rupture extent, but it is likely not the primary reason for the smaller continental normal fault Mmax. Rather, lithosphere yield stress (strength) appears to be the main factor controlling Mmax. In extension, lithosphere is weaker, failing at lower yield stresses than in compression. Although this yield stress difference is consistent with smaller continental normal fault earthquakes, it appears inconsistent with the occurrence of large oceanic normal fault earthquakes. However, the largest oceanic normal fault earthquakes occur near subduction zones where the lithosphere is bending. Laboratory studies indicate that bending lithosphere likely has a higher yield stress than lithosphere in pure extension, which may allow for larger oceanic normal fault earthquakes. Therefore, yield stress—rather than fault geometry alone—appears to be the key factor limiting an earthquake's maximum magnitude. © 2021 Elsevier B.V. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/170875
Appears in Collections: 气候变化与战略
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作者单位: Department of Earth and Planetary Sciences, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208, United States; Institute for Policy Research, Northwestern University, 2040 Sheridan Road, Evanston, IL 60208, United States
Recommended Citation:
Neely J.S.,Stein S.. Why do continental normal fault earthquakes have smaller maximum magnitudes?[J]. Tectonophysics,2021-01-01,809