Rupture Depth-Varying Seismicity Patterns for Major and Great (M_W ≥ 7.0) Megathrust Earthquakes

Large earthquakes on subduction zone plate boundary megathrusts result from intervals of strain accumulation and release. The mechanism diversity and spatial distribution of moderate-size aftershocks is influenced by the mainshock rupture depth extent. Mainshocks that rupture across the shallow megathrust to near the trench have greater intraplate aftershock faulting diversity than events with rupture confined to deeper portions of the megathrust. Diversity of intraplate aftershock faulting also increases as the size of the mainshock approaches the largest size event to have ruptured that region of the megathrust. Based on these tendencies, we identify “breakthrough” ruptures as those involving shallow rupture of the megathrust with volumetrically extensive elastic strain drop around the plate boundary that allows activation of diverse intraplate faulting influenced by long-term ambient deformation stresses. In contrast, homogeneity of the aftershock faulting mechanisms indicates only partial release of elastic strain energy and remaining potential for another large rupture

Systematic deficiency of aftershocks in areas of high coseismic slip for large subduction zone earthquakes

Fault slip during plate boundary earthquakes releases a portion of the shear stress accumulated due to frictional resistance to relative plate motions. Investigation of 101 large [moment magnitude (M_w) ≥ 7] subduction zone plate boundary mainshocks with consistently determined coseismic slip distributions establishes that 15 to 55% of all master event–relocated aftershocks with M_w ≥ 5.2 are located within the slip regions of the mainshock ruptures and few are located in peak slip regions, allowing for uncertainty in the slip models. For the preferred models, cumulative deficiency of aftershocks within the central three-quarters of the scaled slip regions ranges from 15 to 45%, increasing with the total number of observed aftershocks. The spatial gradients of the mainshock coseismic slip concentrate residual shear stress near the slip zone margins and increase stress outside the slip zone, driving both interplate and intraplate aftershock occurrence near the periphery of the mainshock slip. The shear stress reduction in large-slip regions during the mainshock is generally sufficient to preclude further significant rupture during the aftershock sequence, consistent with large-slip areas relocking and not rupturing again for a substantial time

A Paleoseismic Record Spanning 2-Myr Reveals Episodic Late Pliocene Deformation in the Western Qaidam Basin, NE Tibet

Acknowledgments This research was inspired by Prof. Lin Ding's comments on the doctoral thesis proposal of Yin Lu in May 2014 at the Institute of Tibetan Plateau Research, China. We thank Profs. Todd Ehlers, Erwin Appel, and Oliver Friedrich for fruitful discussions in the early stage of this research. We appreciate the editor Germán Prieto for handling our manuscript, Jérôme Nomade and one anonymous reviewer for constructive reviews. We thank Werner Fielitz for comments, A. Koutsodendris, K. S. Nakajima, and H. Campos for help with lab work, and W. Rösler and H. Schulz for help with core sampling. Financial support was provided by the German Research Foundation (# FR2544/13-1 to O. Friedrich) and the University of Liege under Special Funds for Research, IPD-STEMA Program (R.DIVE.0899-JF-G to Y. Lu).Peer reviewedPublisher PD

Systematic deficiency of aftershocks in areas of high coseismic slip for large subduction zone earthquakes

Fault slip during plate boundary earthquakes releases a portion of the shear stress accumulated due to frictional resistance to relative plate motions. Investigation of 101 large [moment magnitude (M_w) ≥ 7] subduction zone plate boundary mainshocks with consistently determined coseismic slip distributions establishes that 15 to 55% of all master event–relocated aftershocks with M_w ≥ 5.2 are located within the slip regions of the mainshock ruptures and few are located in peak slip regions, allowing for uncertainty in the slip models. For the preferred models, cumulative deficiency of aftershocks within the central three-quarters of the scaled slip regions ranges from 15 to 45%, increasing with the total number of observed aftershocks. The spatial gradients of the mainshock coseismic slip concentrate residual shear stress near the slip zone margins and increase stress outside the slip zone, driving both interplate and intraplate aftershock occurrence near the periphery of the mainshock slip. The shear stress reduction in large-slip regions during the mainshock is generally sufficient to preclude further significant rupture during the aftershock sequence, consistent with large-slip areas relocking and not rupturing again for a substantial time

A New Approach to Constrain the Seismic Origin for Prehistoric Turbidites as Applied to the Dead Sea Basin

Acknowledgments The authors appreciate the editor Lucy Flesch for handling our manuscript, Stefano Vitale and Alina Polonia for constructive reviews. This research was supported by the University of Liege under Special Funds for Research, IPD‐STEMA Program (R.DIVE.0899‐J‐F‐G to Y. Lu), Austrian Science Fund (FWF: M 2817 to Y. Lu), the DESERVE Virtual Institute of the Helmholtz Association (to A. Agnon), the Israel Science Foundation (#1093/10 to R.Bookman and #1645/19 to S.Marco), and the ICDP.Peer reviewedPublisher PD

Figure Bundle S1

Comparison between ZnBZ, WnC, and TMC clustering methods for NEIC catalog. Upper rows in each panel show map views of the seismicity (M≥5.0) with background events (gray) that occurred prior to the mainshock (triangles) or after (circles). The identified foreshocks are plotted in blue (triangles) and aftershocks in red (circles). The magenta circles represent the effective radius of the mainshock (see Eq. 1). Focal mechanism solution of the mainshock is from the GCMT catalog.  Time lines, with nonlinear scale are shown for the seismicity in each map as functions of magnitude (middle row of each panel) and epicentral distance from the mainshock* (lower row of each panel), with the same color scheme.</p

Systematic deficiency of aftershocks in areas of high coseismic slip for large subduction zone earthquakes.

Fault slip during plate boundary earthquakes releases a portion of the shear stress accumulated due to frictional resistance to relative plate motions. Investigation of 101 large [moment magnitude (Mw) ≥ 7] subduction zone plate boundary mainshocks with consistently determined coseismic slip distributions establishes that 15 to 55% of all master event-relocated aftershocks with Mw ≥ 5.2 are located within the slip regions of the mainshock ruptures and few are located in peak slip regions, allowing for uncertainty in the slip models. For the preferred models, cumulative deficiency of aftershocks within the central three-quarters of the scaled slip regions ranges from 15 to 45%, increasing with the total number of observed aftershocks. The spatial gradients of the mainshock coseismic slip concentrate residual shear stress near the slip zone margins and increase stress outside the slip zone, driving both interplate and intraplate aftershock occurrence near the periphery of the mainshock slip. The shear stress reduction in large-slip regions during the mainshock is generally sufficient to preclude further significant rupture during the aftershock sequence, consistent with large-slip areas relocking and not rupturing again for a substantial time