Estimating ocean variables using ambient noise interferometry

2021 ◽  
Vol 150 (4) ◽  
pp. A82-A82
Author(s):  
John Ragland ◽  
Shima Abadi
Keyword(s):  
Ambient Noise ◽  
Noise Interferometry

A linear algorithm for ambient seismic noise double beamforming without explicit crosscorrelations

Geophysics ◽  
2021 ◽  
Vol 86 (1) ◽  
pp. F1-F8
Author(s):  
Eileen R. Martin
Keyword(s):  
Correlation Functions ◽  
Seismic Noise ◽  
Ambient Noise ◽  
Computational Cost ◽  
Body Waves ◽  
Ambient Seismic Noise ◽  
Noise Correlation ◽  
Dense Array ◽  
Near Surface ◽  
Noise Interferometry

Geoscientists and engineers are increasingly using denser arrays for continuous seismic monitoring, and they often turn to ambient seismic noise interferometry for low-cost near-surface imaging. Although ambient noise interferometry greatly reduces acquisition costs, the computational cost of pair-wise comparisons between all sensors can be prohibitively slow or expensive for applications in engineering and environmental geophysics. Double beamforming of noise correlation functions is a powerful technique to extract body waves from ambient noise, but it is typically performed via pair-wise comparisons between all sensors in two dense array patches (scaling as the product of the number of sensors in one patch with the number of sensors in the other patch). By rearranging the operations involved in the double beamforming transform, I have developed a new algorithm that scales as the sum of the number of sensors in two array patches. Compared to traditional double beamforming of noise correlation functions, the new method is more scalable, easily parallelized, and it does not require raw data to be exchanged between dense array patches.

Volcano Ambient Noise Interferometry in the Caribbean (VANIC)

2020 ◽  
Author(s):  
Reinoud Sleeman
Keyword(s):  
Ambient Noise ◽  
Seismic Velocity ◽  
Volcano Seismology ◽  
Base Level ◽  
Noise Interferometry ◽  
Single Station ◽  
Cross Correlations ◽  
The Caribbean ◽  
Velocity Variations ◽  
Seismic Networks

<p><span><span>The hazardous stratovolcanoes in the Lesser Antilles island arc are monitored with sparse seismic networks. The application of ambient noise interferometry to monitor seismic velocity variations (dv/v) on data from such a sparse instrumented volcanic environment often is a challenge. For the purpose of monitoring it is important a) to analyse the applicability of, and differences between, cross- and single-station cross-correlations, b) to estimate the base level of seismic velocity variations during quiet times and c) to understand the characteristics. Within the EUROVOLC instrument “Transnational Access (TA)” a proposal called VANIC was supported to a) use and evaluate different types of ambient noise cross correlations (single stations vs. multiple stations; auto, cross and cross-component correlations) to be applied on seismic recordings from the Guadeloupe seismic network on La Soufriere, b) compare the results with dv/v base level estimates from the sparse Netherlands Caribbean network on The Quill and Mt. Scenery and c) start collaboration between OVSG and KNMI on both monitoring and research levels with a focus on volcano seismology. This presentation will focus is on the results obtained during the TA visit to OVGS.</span></span></p>

scholarly journals Radial anisotropy in the crust of SE Tibet and SW China from ambient noise interferometry

2010 ◽  
Vol 37 (21) ◽  
pp. n/a-n/a ◽  
Author(s):  
Hui Huang ◽  
Huajian Yao ◽  
Robert D. van der Hilst
Keyword(s):  
Ambient Noise ◽  
Sw China ◽  
Noise Interferometry ◽  
Radial Anisotropy ◽  
Se Tibet

scholarly journals Fault detection by reflected surface waves based on ambient noise interferometry

2021 ◽  
pp. 100035
Author(s):  
G.U. Ning ◽  
Z.H.A.N.G. Haijiang ◽  
Nori NAKATA ◽  
G.A.O. Ji
Keyword(s):  
Fault Detection ◽  
Surface Waves ◽  
Ambient Noise ◽  
Noise Interferometry

scholarly journals Seismic velocity changes at White Island volcano, New Zealand, using ten years of ambient noise interferometry

2021 ◽  
Author(s):  
◽  
Alexander Yates
Keyword(s):  
Ambient Noise ◽  
Seismic Velocity ◽  
Environmental Influence ◽  
Seismic Stations ◽  
Noise Interferometry ◽  
Stress Changes ◽  
Volcanic Processes ◽  
Seismic Velocity Changes ◽  
Velocity Changes ◽  
White Island

<p>Seismic velocity changes at volcanoes carry information about stresses present within hydrothermal and magmatic systems. In this thesis, temporal velocity changes are measured at White Island volcano using ambient noise interferometry between 2007–2017. This period contains multiple well-documented eruptions starting in 2012, following an inactive period that extends back over a decade. Three primary objectives are identified: (1) investigate what seismic velocity changes can tell us about dynamic changes beneath the volcano, (2) investigate non-volcanic sources and their possible influence on interpretations, and (3) consider the potential for real-time monitoring using ambient-noise. These objectives extend beyond White Island volcano, with implications for ambient noise monitoring of volcanoes globally.  Two different approaches are used to measure velocity changes at White Island. The first involves cross-correlating noise recorded by pairs of seismic stations. Velocity changes are sought by averaging changes recorded across ten station-pairs that consist of an onshore station and a station on the volcano. The second approach involves cross-correlating the different components of individual seismic stations. This represents a less traditional approach to monitoring volcanoes, but is well-suited to White Island which has one permanent station active throughout eruptive activity. Single seismic stations located onshore are also processed to investigate background regional changes.  Two periods of long-term velocity increases are detected at the volcano. The first occurs during a highly active period in 2012–2013 and the second occurs in the months preceding an explosive eruption in April 2016. Comparison with velocities recorded by onshore stations suggest a meteorological source for these changes is unlikely. Velocity increases are therefore interpreted to reflect cracks closing under increased pressures beneath the volcano. Similarly, a rapid decline in the velocity within 2–3 months of the April 2016 eruption is interpreted to reflect depressurization of the system.  In addition to volcanic sources, we also find clear evidence of non-volcanic processes influencing velocity changes at the volcano. Two clear co-seismic velocity decreases of approximately 0.05–0.1% are associated with a Mw 5.2 earthquake in 2008 — within 10 km of the volcano — and the Mw 7.1 East Cape earthquake in 2016. The East Cape earthquake — located 200 km away from the volcano — produces significant velocity decreases over a large region, as detected by stations onshore and on White Island. This likely reflects dynamic stress changes as a result of passing seismic waves, with an eruption two weeks later interpreted here to have been triggered by this event. Finally, we identify similarities between annual variations recorded by onshore stations and changes at the volcano, suggesting an environmental influence. Velocity changes at White Island therefore represent a complex interaction of volcanic and non-volcanic processes, highlighting the need for improved understanding of external sources of change to accurately detect short-term eruptive precursors.</p>

Depth variations of 410 km and 660 km discontinuities in eastern North China Craton revealed by ambient noise interferometry

2017 ◽  
Vol 44 (16) ◽  
pp. 8328-8335 ◽  
Author(s):  
Jikun Feng ◽  
Huajian Yao ◽  
Piero Poli ◽  
Lihua Fang ◽  
Yan Wu ◽  
...  
Keyword(s):  
North China Craton ◽  
Ambient Noise ◽  
North China ◽  
Noise Interferometry

Retrieval of Body-Wave Reflections Using Ambient Noise Interferometry Using a Small-Scale Experiment

2018 ◽  
Vol 175 (6) ◽  
pp. 2009-2022 ◽  
Author(s):  
Odmaksuel Anísio Bezerra Dantas ◽  
Aderson Farias do Nascimento ◽  
Martin Schimmel
Keyword(s):  
Ambient Noise ◽  
Body Wave ◽  
Small Scale ◽  
Wave Reflections ◽  
Noise Interferometry ◽  
Scale Experiment
Sign in / Sign up

Export Citation Format

Share Document