The equatorial Indian Ocean is a well-known place of intraplate deformation and the deformed area has been interpreted as a diffuse plate boundary between India and Australia (Wiens et al.

Emerged late Quaternary coral reefs show that on the lo3 to IO5 years time scale the western part of the central New Hebrides arc is divided into several semi-independent uplifted blocks. The blocks are separated by tectonic discontinuities, oriented approximately normal to the arc trend, across which tilt directions or uplift change suddenly. However, none of the blocks is tilted in a direction normal to the arc trend of N20"W. Two of the discontinuities, across Santo and Malekula Islands, occur near the places where ridges on the north and south flanks of the d'Entrecasteaux fracture zone, a major bathymetric feature on the underthrusting plate, intersect the arc. Each of these tectonic discontinuities approximately coincides with one end of the rupture zone inferred .for a shallow thrust-type earthquake sequence in 1965. The discontinuity across Santo also nearly coincides with the south end of the rupture zone inferred for another earthquake sequence in [1973][1974]

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Earthquakes for the period 1962–1973 are relocated by the method of joint hypocenter determination in order to resolve better the configuration and structure of the inclined seismic zone in the New Hebrides island arc. Twelve new focal mechanism solutions are reported and, together with previously published solutions, are integrated with the new information on the spatial distribution of hypocenters. At intermediate depths the seismic zone has a uniformly steep dip of about 70° and exhibits no resolvable contortions or disruptions along at least 700 km of the subduction zone. The thickness of the zone, about 20 km, may be in part due to seismically active fault zones which cut across a portion of the descending lithosphere. Features associated with the anomalous central region of the arc, where the d'Entrecasteaux fracture zone is being subducted and where the islands of Santo and Malekula appear to be in positions normally occupied by the oceanic trench, include the following: (1) an inclined zone of shallow earthquakes with very much smaller dip than is found elsewhere in the arc, (2) a pronounced gap in seismic activity at depths between about 50 and 120 km, (3) evidence for features in the upper or overthrust plate with trends transverse to the arc and parallel to the east‐west trends of the topographic feature being subducted, including nodal planes of shallow focal mechanism solutions, and (4) two features which appear to coincide with the downdip projection of the northern scarp of the d'Entrecasteaux fracture zone, including a well‐defined boundary between two adjacent zones of plate slippage along the main plate boundary and a faultlike feature in the intermediate depth seismic zone which also has a strike parallel to the fracture zone. Appendix table and entire article are available on microfiche.Order from American Geophysical Union, 1909 K Street, N.W.,Washington, D. C., 20006. Document J78‐006; $1.00. Payment mustaccompany order.

RPA-coated single-stranded DNA (RPA–ssDNA), a nucleoprotein structure induced by DNA damage, promotes ATR activation and homologous recombination (HR). RPA is hyper-phosphorylated and ubiquitylated after DNA damage. The ubiquitylation of RPA by PRP19 and RFWD3 facilitates ATR activation and HR, but how it is stimulated by DNA damage is still unclear. Here, we show that RFWD3 binds RPA constitutively, whereas PRP19 recognizes RPA after DNA damage. The recruitment of PRP19 by RPA depends on PIKK-mediated RPA phosphorylation and a positively charged pocket in PRP19. An RPA32 mutant lacking phosphorylation sites fails to recruit PRP19 and support RPA ubiquitylation. PRP19 mutants unable to bind RPA or lacking ubiquitin ligase activity also fail to support RPA ubiquitylation and HR. These results suggest that RPA phosphorylation enhances the recruitment of PRP19 to RPA–ssDNA and stimulates RPA ubiquitylation through a process requiring both PRP19 and RFWD3, thereby triggering a phosphorylation-ubiquitylation circuitry that promotes ATR activation and HR.

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Results of long-term experimental studies and modelling of faulting are briefly reviewed, and research methods and the-state-of-art issues are described. The article presents the main results of faulting modelling with the use of non-transparent elasto-viscous plastic and optically active models. An area of active dynamic influence of fault (AADIF) is the term introduced to characterise a fault as a 3D geological body. It is shown that AADIF's width (М) is determined by thickness of the layer wherein a fault occurs (Н), its viscosity (η) and strain rate (V). Multiple correlation equations are proposed to show relationships between AADIF's width (М), H, η and V for faults of various morphological and genetic types. The irregularity of AADIF in time and space is characterised in view of staged formation of the internal fault structure of such areas and geometric and dynamic parameters of AADIF which are changeable along the fault strike. The authors pioneered in application of the open system conception to find explanations of regularities of structure formation in AADIFs. It is shown that faulting is a synergistic process of continuous changes of structural levels of strain, which differ in manifestation of specific selfsimilar fractures of various scales. Such levels are changeable due to self-organization processes of fracture systems. Fracture dissipative structures (FDS) is the term introduced to describe systems of fractures that are subject to self-organization. It is proposed to consider informational entropy and fractal dimensions in order to reveal FDS in AADIF. Studied are relationships between structure formation in AADIF and accompanying processes, such as acoustic emission and terrain development above zones wherein faulting takes place.Optically active elastic models were designed to simulate the stress-and-strain state of AADIF of main standard types of fault jointing zones and their analogues in nature, and modelling results are reported in the article. A good correlation is revealed between the available seismological, structural geological and geodetic data.