Ambient noise surface wave tomography of the Iranian Plateau

Mottaghi, Ali Asghar; Rezapour, Mehdi; Korn, M.

doi:10.1093/gji/ggs134

Cited by 31 publications

(16 citation statements)

References 36 publications

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“…Figure a shows that for periods between 6 and 30 s the average group velocity uncertainties are less than 0.1 km/s, dropping significantly for intermediate periods to ~0.05 km/s. For phase velocities, the standard deviation is much smaller, ranging from ~0.06 to ~0.1 km/s, with a minimum of 0.04 km/s at 14–22 s. Our uncertainties are similar to those reported in independent studies with similar data sets (e.g., Dias et al, ; Lin et al, ; Mottaghi et al, ). The greatest uncertainties are for periods >30 s, which we believe are due to the decrease in amplitude of the microseismic noise spectrum at those periods that make it difficult to recover the empirical Green's function.…”

Section: Phase and Group Velocity Tomographysupporting

confidence: 87%

“…Indeed, an ever increasing number of ambient seismic noise studies have been produced during the last decade mapping different parts of the globe (e.g., Abdetedal et al, ; Bensen et al, ; Boué et al, ; Haned et al, ; Lin et al, ; Mottaghi et al, ; Saygin & Kennett, ; Shapiro et al, ; Stehly et al, ; Villaseñor et al, ; Ward et al, ; Yang et al, ; Yao et al, ). These studies have conclusively demonstrated that empirical Green's function recovery from average cross correlations of ambient noise between pairs of seismic stations is capable of providing tight constraints on upper and middle crustal structure.…”

Section: Introductionmentioning

confidence: 99%

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Upper and Middle Crustal Velocity Structure of the Colombian Andes From Ambient Noise Tomography: Investigating Subduction‐Related Magmatism in the Overriding Plate

et al. 2018

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New maps of S velocity variation for the upper and middle crust making up the northwestern most corner of South America have been developed from cross correlation of ambient seismic noise at 52 broadband stations in the region. Over 1,300 empirical Green's functions, reconstructing the Rayleigh wave portion of the seismic wavefield, were obtained after time and frequency‐domain normalization of the ambient noise recordings and stacking of 48 months of normalized data. Interstation phase and group velocity curves were then measured in the 6–38 s period range and tomographically inverted to produce maps of phase and group velocity variation in a 0.5° × 0.5° grid. Velocity‐depth profiles were developed for each node after simultaneously inverting phase and group velocity curves and combined to produce 3‐D maps of S velocity variation for the region. The S velocity models reveal a ~7 km thick sedimentary cover in the Caribbean region, the Magdalena Valley, and the Cordillera Oriental, as well as crustal thicknesses in the Pacific and Caribbean region under ~35 km, consistent with previous studies. They also display zones of slow velocity at 25–35 km depth under regions of both active and inactive volcanism, suggesting the presence of melts that carry the signature of segmented subduction into the overriding plate. A low‐velocity zone in the same depth range is imaged under the Lower Magdalena Basin in the Caribbean region, which may represent either sublithospheric melts ponding at midcrustal levels after breaching through a fractured Caribbean flat slab or fluid migration through major faults within the Caribbean crust.

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Section: Phase and Group Velocity Tomographysupporting

confidence: 87%

Section: Introductionmentioning

confidence: 99%

Upper and Middle Crustal Velocity Structure of the Colombian Andes From Ambient Noise Tomography: Investigating Subduction‐Related Magmatism in the Overriding Plate

et al. 2018

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“…Then we can perform tomographic inversions using the surface wave velocities for each period as input (e.g. Shapiro et al 2005;Sabra et al 2005;Villaseñor et al 2007;Yang et al 2007;Lin et al 2008;Mottaghi et al 2013;Silveira et al 2013;Nicholson et al 2014;Dias et al 2015). Finally, the inversion of group velocities in each point of a grid can be used to obtain layered profiles of S-wave velocity, which are further interpolated to compute 2-D maps.…”

Section: Introductionmentioning

confidence: 99%

Ambient noise tomography of the southern sector of the Cantabrian Mountains, NW Spain

Acevedo

Fernández‐Viejo

Llana‐Fúnez

et al. 2019

Geophysical Journal International

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SUMMARY This study presents the first detailed analysis of ambient noise tomography in an area of the continental upper crust in the Cantabrian Mountains (NW Spain), where a confluence of crustal scale faults occurs at depth. Ambient noise data from two different seismic networks have been analysed. In one side, a 10-short-period station network was set recording continuously for 19 months. A second set of data from 13 broad-band stations was used to extend at depth the models. The phase cross-correlation processing technique was used to compute in total more than 34 000 cross-correlations from 123 station pairs. The empirical Green's functions were obtained by applying the time–frequency, phase-weighted stacking methodology and provided the emergence of Rayleigh waves. After measuring group velocities, Rayleigh-wave group velocity tomographic maps were computed at different periods and then they were inverted in order to calculate S-wave velocities as a function of depth, reaching the first 12 km of the crust. The results show that shallow velocity patterns are dominated by geological features that can be observed at the surface, particularly bedding and/or lithology and fracturing associated with faults. In contrast, velocity patterns below 4 km depth seem to be segmented by large structures, which show a velocity reduction along fault zones. The best example is the visualization in the tomography of the frontal thrust of the Cantabrian Mountains at depth, which places higher velocity Palaeozoic rocks over Cenozoic sediments of the foreland Duero basin. One of the major findings in the tomographic images is the reduction of seismic velocities above the area in the crust where one seismicity cluster is nucleated within the otherwise quiet seismic area of the range. The noise tomography reveals itself as a valuable technique to identify shear zones associated with crustal scale fractures and hence, lower strain areas favourable to seismicity.

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“…14 ), joint gravity and surface wave tomography 15 , and ambient seismic noise tomography (e.g. 16 and 17 ). However, few results about crustal structure have been published.…”

Section: Introductionmentioning

confidence: 99%

Crustal Structure of the Collision-Subduction Zone in South of Iran Using Virtual Seismometers

Shirzad

Riahi

Assumpção

2019

Sci Rep

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Improving the resolution of seismic tomography by adding virtual seismometers is an ambitious aim in regions with poor instrumental coverage. In this study, inter-event empirical Green’s functions (EGFs) were retrieved using cross-correlation of the vertical component of 630 earthquakes with M ≥ 4 which occurred around the collision-subduction transition zone in south Iran. To extract reliable inter-event EGFs and obtain stable tomographic results, we used about 1300 event pairs with good signal-to-noise ratio, each pair well aligned to a seismic station. Our results show that the retrieved inter-event EGFs agree well with those obtained from earthquakes in similar paths. The inverted velocity model presents two main layers including upper crust (up to ~16 km) and middle crust (deeper than ~18 km) in both sides of the Minab-Zendan-Palami transition zone. The upper crust contains two main layers: sedimentary and basement layers with thicknesses ~6 and ~10 km, respectively. Moreover, the main faults cause lateral variations in these main layers. The difference between the average velocities of the middle crust, between the collision and subduction zones, is about 0.5 km/s, delimited by faults. Also, an area with a 30 km width along these faults can be defined as the collision-subduction transition zone.

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Ambient noise surface wave tomography of the Iranian Plateau

Cited by 31 publications

References 36 publications

Upper and Middle Crustal Velocity Structure of the Colombian Andes From Ambient Noise Tomography: Investigating Subduction‐Related Magmatism in the Overriding Plate

Upper and Middle Crustal Velocity Structure of the Colombian Andes From Ambient Noise Tomography: Investigating Subduction‐Related Magmatism in the Overriding Plate

Ambient noise tomography of the southern sector of the Cantabrian Mountains, NW Spain

Crustal Structure of the Collision-Subduction Zone in South of Iran Using Virtual Seismometers

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