A Comparative Field Trial of a New Nimble Node and Cabled Systems in a Desert Environment

Ourabah, Amine; Crosby, Alistair; Brooks, Chris; Manning, E.; Lythgoe, Karen; Ablyazina, D.; Zhuzhel, Victor; Holst, Einar; Knutsen, T

doi:10.3997/2214-4609.201901136

Cited by 6 publications

(1 citation statement)

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“…Seismic nodes can be deployed rapidly, directly into the ground and without any bulky equipment. Nodes-short period autonomous geophones-were originally developed in the energy industry for shallow land imaging with active sources (e.g., Manning et al, 2019, Ourabah et al, 2019. However, several recent studies have demonstrated the utility of nodes for passive seismic imaging on a basin or lithospheric scale (Lin et al, 2013;Liu et al, 2018;Ward et al, 2018;Wang et al, 2019).…”

Section: 1029/2020gl087233mentioning

confidence: 99%

Large‐Scale Crustal Structure Beneath Singapore Using Receiver Functions From a Dense Urban Nodal Array

Lythgoe

Qing

Wei

2020

Geophysical Research Letters

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Geophysics has a role to play in the development of "smart cities". This is particularly true for Singapore, one of the world's most densely populated countries. Imaging of Singapore's subsurface is required to identify geological faults, model shaking from future earthquakes, and provide a framework for underground development. A noninvasive geophysical technique that is well suited for urban areas is passive seismic surveys using compact seismic instruments called nodes. Here we image Singapore's crustal structure using receiver functions generated by a 40-day deployment of a 88 station nodal array. We generate high resolution receiver functions, despite the noisy environment and short recording time and also create common-conversion point images. Our results reveal a complex crustal structure, containing multiple discontinuities. Azimuthal variations indicate a distinct change in crustal structure on either side of the postulated Bukit Timah fault, which has implications for seismic hazard.Plain Language Summary By 2050 over two thirds of the global population is expected to live in cities (United Nations, Department of Economic and Social Affairs, Population Division, 2019). Such dense population centers increase the exposure to nearby natural hazards such as earthquakes. Rapid urbanization also creates an ever pressing need to understand the subsurface of our cities, for example, for underground development. One technological advancement that allows us to image the subsurface of cities are passive seismic surveys using nodes. Nodes are small seismic instruments that can be deployed in urban areas such as schools and parks. We present results of a passive seismic survey using 88 nodes deployed in Singapore for 40 days. We generate high resolution receiver functions across the array, despite the short recording time, by using array stacking techniques. The dense nature of the array also allows continuous high frequency signals to be traced. Our results reveal that the structure of the crust is different on either side of the Bukit Timah fault, which agrees with geological information. Ancient faults in peninsula Malaysia have been reactivated in the recent past due to stress transfer from the Sumatran subduction zone; therefore, a geological fault under a densely populated urban center warrants further study for seismic hazard.

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Section: 1029/2020gl087233mentioning

confidence: 99%

Large‐Scale Crustal Structure Beneath Singapore Using Receiver Functions From a Dense Urban Nodal Array

Lythgoe

Qing

Wei

2020

Geophysical Research Letters

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Free-surface elastic wave injection and wavefield reconstruction with applications to elastic reverse time migration

Han

Xie

2023

GEOPHYSICS

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Accurately injecting and extrapolating multicomponent seismic data is a major step in elastic reverse time migration (RTM) and full waveform inversion (FWI). The theoretical basis of this process is the seismic representation theorem. We propose a numerical approach based on the collocated-grid MacCormack finite-difference (FD) scheme to implement the injection and extrapolation. The MacCormack FD scheme defines wavefield parameters on the same grid. When dealing with the boundary condition in the representation theorem, it is more advantageous than the commonly used staggered-grid FD scheme which defines the stress and velocity on offset grids; thus interpolations are required to link the boundary values to nearby nodes. On the contrast, with the MacCormack scheme, the traction and particle velocity data can be directly injected to the boundary nodes as equivalent concentrated forces, force dipoles and double couples. The accuracy of this approach is validated by comparing the regenerated wavefield with the original wavefield. Our primary purpose is to develop an injection method for elastic RTM, but this approach can also be used to numerically investigate other interesting issues in the elastic wave injection, including errors and artifacts caused by injection from unclosed boundaries, incomplete boundary values, and uncertain velocity models. In particular, seismic data are usually acquired on the ground surface where the traction-free condition is naturally maintained. We simulate a land acquisition scenario by generating a synthetic multicomponent dataset on a traction-free surface. The reconstructed wavefields from velocity data are compared to the original forward propagated waves to evaluate the accuracy of the boundary treatments. Two multicomponent elastic RTM examples are presented to demonstrate the applications of the proposed injection method. By combining the regenerated receiver-side wavefield and the vectorized image condition, the PP, PS, SP and SS images are calculated.

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A 184 million traces per km² seismic survey with nodes – acquisition and processing

Ourabah¹,

Crosby²

2020

SEG Technical Program Expanded Abstracts 2020

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A Comparative Field Trial of a New Nimble Node and Cabled Systems in a Desert Environment

Cited by 6 publications

References 0 publications

Large‐Scale Crustal Structure Beneath Singapore Using Receiver Functions From a Dense Urban Nodal Array

Large‐Scale Crustal Structure Beneath Singapore Using Receiver Functions From a Dense Urban Nodal Array

Free-surface elastic wave injection and wavefield reconstruction with applications to elastic reverse time migration

A 184 million traces per km² seismic survey with nodes – acquisition and processing

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A Comparative Field Trial of a New Nimble Node and Cabled Systems in a Desert Environment

Cited by 6 publications

References 0 publications

Large‐Scale Crustal Structure Beneath Singapore Using Receiver Functions From a Dense Urban Nodal Array

Large‐Scale Crustal Structure Beneath Singapore Using Receiver Functions From a Dense Urban Nodal Array

Free-surface elastic wave injection and wavefield reconstruction with applications to elastic reverse time migration

A 184 million traces per km2 seismic survey with nodes – acquisition and processing

Contact Info

Product

Resources

About

A 184 million traces per km² seismic survey with nodes – acquisition and processing