Regional seismicity of the Mid-Atlantic Ridge: observations from autonomous hydrophone arrays

Simão, Nuno; Escartı́n, J.; Goslin, Jean; Haxel, J. H.; Cannat, Mathilde; Dziak, Robert P.

doi:10.1111/j.1365-246x.2010.04815.x

Cited by 35 publications

(54 citation statements)

References 91 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…A single-link cluster analysis identified earthquake clusters in time and space. Owing to their long observation period, teleseismic earthquake catalogues of mid-ocean ridges can reproduce the main features of along-axis seismicity variations on a regional scale that are visible in more complete catalogues of hydroacoustically recorded events 28 . We project the event locations onto our profiles in Fig.…”

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Mid-ocean-ridge seismicity reveals extreme types of ocean lithosphere

Schlindwein

Schmid

2016

Nature

127

148

View full text Add to dashboard Cite

Along ultraslow-spreading ridges, where oceanic tectonic plates drift very slowly apart, conductive cooling is thought to limit mantle melting and melt production has been inferred to be highly discontinuous. Along such spreading centres, long ridge sections without any igneous crust alternate with magmatic sections that host massive volcanoes capable of strong earthquakes. Hence melt supply, lithospheric composition and tectonic structure seem to vary considerably along the axis of the slowest-spreading ridges. However, owing to the lack of seismic data, the lithospheric structure of ultraslow ridges is poorly constrained. Here we describe the structure and accretion modes of two end-member types of oceanic lithosphere using a detailed seismicity survey along 390 kilometres of ultraslow-spreading ridge axis. We observe that amagmatic sections lack shallow seismicity in the upper 15 kilometres of the lithosphere, but unusually contain earthquakes down to depths of 35 kilometres. This observation implies a cold, thick lithosphere, with an upper aseismic zone that probably reflects substantial serpentinization. We find that regions of magmatic lithosphere thin dramatically under volcanic centres, and infer that the resulting topography of the lithosphere-asthenosphere boundary could allow along-axis melt flow, explaining the uneven crustal production at ultraslow-spreading ridges. The seismicity data indicate that alteration in ocean lithosphere may reach far deeper than previously thought, with important implications towards seafloor deformation and fluid circulation.

show abstract

Section: Methodsmentioning

confidence: 99%

“…Exhumation of mantle lithosphere along major detachment faults produces substantial earthquake activity at the Mid-Atlantic Ridge 13,28 . The seismicity delineates the detachment faults to depths of 7 km into the shallow upper mantle 29 .…”

Section: Letter Researchmentioning

confidence: 99%

Mid-ocean-ridge seismicity reveals extreme types of ocean lithosphere

Schlindwein

Schmid

2016

Nature

127

148

View full text Add to dashboard Cite

show abstract

“…The spatial and temporal patterns of earthquakes recorded by autonomous hydrophones on the northern MAR (Smith et al 2003;Simão et al 2010) show no simple relationship to second-order segment variables (e.g. length or trend of the segment, maximum offset of discontinuities or along-axis change in MBA and water depths).…”

Section: Geophysical Properties Of Discontinuities and Ridge Segmentsmentioning

confidence: 99%

Tectonic and magmatic segmentation of the Global Ocean Ridge System: a synthesis of observations

Carbotte

Smith

Cannat

et al. 2015

View full text Add to dashboard Cite

Mid-ocean ridges display tectonic segmentation defined by discontinuities of the axial zone, and geophysical and geochemical observations suggest segmentation of the underlying magmatic plumbing system. Here, observations of tectonic and magmatic segmentation at ridges spreading from fast to ultraslow rates are reviewed in light of influential concepts of ridge segmentation, including the notion of hierarchical segmentation, spreading cells and centralized v. multiple supply of mantle melts. The observations support the concept of quasi-regularly spaced principal magmatic segments, which are 30-50 km long on average at fast-to slow-spreading ridges and fed by melt accumulations in the shallow asthenosphere. Changes in ridge properties approaching or crossing transform faults are often comparable with those observed at smaller offsets, and even very small discontinuities can be major boundaries in ridge properties. Thus, hierarchical segmentation models that suggest large-scale transform fault-bounded segmentation arises from deeper level processes in the asthenosphere than the finer-scale segmentation are not generally supported. The boundaries between some but not all principal magmatic segments defined by ridge axis geophysical properties coincide with geochemical boundaries reflecting changes in source composition or melting processes. Where geochemical boundaries occur, they can coincide with discontinuities of a wide range of scales.Discovery and interpretations of mid-ocean ridge (MOR) segmentation: historical review

show abstract

“…5). These dyke intrusions interact with the FMA producing more prolific shorter duration seismic sequences (also refer Simão et al 2010). These sequences are already detailed in Table 1.…”

Section: Resultsmentioning

confidence: 96%

Seismic Clusters and their Characteristics at the Arabian Sea Triple Junction: Supportive Evidences for Plate Margin Deformations

Mukhopadhyay

Dasgupta

2011

Journal of the Geological Society of India

View full text Add to dashboard Cite

The plate margin features defining the Arabian Sea Triple Junction (ASTJ) are: the Aden Ridge (AR), Sheba Ridge (SR) with their intervening Alula-Fartak Transform (AFT), Carlsberg Ridge (CR) and Owen Fracture Zone (OFZ). Exact nature of ASTJ is presently debated: whether it is RRF (ridge-ridge-fault) or RRR (ridge-ridge-ridge) type. A revised seismicity map for ASTJ is given here using data for a period little more than a century. "Point density spatial statistical criterion" is applied to short-listed 742 earthquakes (mb ≥ 4.3), 10 numbers of spatio-temporal seismic clusters are identified for ASTJ and its arms. Relocated hypocentres help better constraining the cluster identification wherever such data exist. Seismic clusters actually diagnose the most intense zones of strain accumulation due to far field as well as the local stress operating at ASTJ. An earthquake swarm emanating from a prominent seismic cluster below SR provides an opportunity to investigate the pore pressure diffusion process (due to the active source) by means of "r-t plot". Stress and faulting pattern in the active zones are deduced from 43 CMT solutions. While normal or lateral faulting is characteristic for these arms, an anomalous thrust earthquake occurs in the triangular 'Wheatley Deep' deformation zone proximal to ASTJ. The latter appears to have formed due to a shift of the deformational front from OFZ towards a transform that offsets SR. Though ASTJ is still in the process of evolution, available data favour that this RRF triple junction may eventually be converted to a more stable RRR type.

show abstract

Regional seismicity of the Mid-Atlantic Ridge: observations from autonomous hydrophone arrays

Cited by 35 publications

References 91 publications

Mid-ocean-ridge seismicity reveals extreme types of ocean lithosphere

Mid-ocean-ridge seismicity reveals extreme types of ocean lithosphere

Tectonic and magmatic segmentation of the Global Ocean Ridge System: a synthesis of observations

Seismic Clusters and their Characteristics at the Arabian Sea Triple Junction: Supportive Evidences for Plate Margin Deformations

Contact Info

Product

Resources

About