Matched Field Acoustics

Kuperman, W. A.; Turek, Gabriella

doi:10.1006/mssp.1996.0066

Cited by 28 publications

(14 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…5 for the event indicated in Figs 2 and 3 by the yellow star and vertical red line, respectively. The array-based location is done with a modified version of the matched-field processing (MFP) algorithm of Kuperman & Turek (1997) and Cros et al (2011), and projecting phase delays of the MFP onto a 3-D grid with the linear Bartlett operator. Additional details on this location technique are given in the supplementary material.…”

Section: R E S U Lt Smentioning

confidence: 99%

Basic data features and results from a spatially dense seismic array on the San Jacinto fault zone

Ben‐Zion

Vernon

Ozakin

et al. 2015

Geophysical Journal International

128

111

View full text Add to dashboard Cite

We discuss several outstanding aspects of seismograms recorded during >4 weeks by a spatially dense Nodal array, straddling the damage zone of the San Jacinto fault in southern California, and some example results. The waveforms contain numerous spikes and bursts of high-frequency waves (up to the recorded 200 Hz) produced in part by minute failure events in the shallow crust. The high spatial density of the array facilitates the detection of 120 small local earthquakes in a single day, most of which not detected by the surrounding ANZA and regional southern California networks. Beamforming results identify likely ongoing cultural noise sources dominant in the frequency range 1-10 Hz and likely ongoing earthquake sources dominant in the frequency range 20-40 Hz. Matched-field processing and back-projection of seismograms provide alternate event location. The median noise levels during the experiment at different stations, waves generated by Betsy gunshots, and wavefields from nearby earthquakes point consistently to several structural units across the fault. Seismic trapping structure and local sedimentary basin produce localized motion amplification and stronger attenuation than adjacent regions. Cross correlations of high-frequency noise recorded at closely spaced stations provide a structural image of the subsurface material across the fault zone. The high spatial density and broad frequency range of the data can be used for additional high resolution studies of structure and source properties in the shallow crust.

show abstract

Section: R E S U Lt Smentioning

confidence: 99%

Basic data features and results from a spatially dense seismic array on the San Jacinto fault zone

Ben‐Zion

Vernon

Ozakin

et al. 2015

Geophysical Journal International

128

111

View full text Add to dashboard Cite

show abstract

“…The Sage Brush Flat (SGB) site on the San Jacinto Fault Zone (SJFZ) southeast of Anza, California is the location of a previous dense geophone deployment (Ben‐Zion et al, ) and various studies associated with detailed imaging of the subsurface material (Hillers et al, ; Mordret et al, ; Roux et al, ) and detection of small earthquakes and air‐traffic events (Meng & Ben‐Zion, , ). Using a frequency‐domain matched‐field processing technique involving beamforming and backprojection of continuous array data (Corciulo et al, ; Kuperman & Turek, ), very small events were detected at the SGB site and were found to cluster near structures, fences, and within the vegetation. The locations suggest that these events are associated with shallow ground motion generated at the foundations of these objects by wind gusts (Gradon et al, ).…”

Section: Introductionmentioning

confidence: 99%

Characteristics of Ground Motion Generated by Wind Interaction With Trees, Structures, and Other Surface Obstacles

et al. 2019

View full text Add to dashboard Cite

Analysis of continuous seismic waveforms from a temporary deployment at Sage Brush Flats on the San Jacinto fault reveals earthquake‐ and tremor‐like signals generated by the interaction of wind with obstacles above the surface. Tremor‐like waveforms are present at the site during wind velocities above 2 m/s, which occur for 70% of the deployment duration. The response to the wind has significant spatial variability with highest ground motions near large surface objects. The wind‐related signals show ground velocities that exceed the average ground motions of M1.0–1.5 earthquakes for 6–31% of the day. Waveform spectra indicate a modulation of amplitude that correlates with wind velocity and distance from local structures. Earthquake‐like signals are found to originate from local structures and vegetation, and are modified on length scales of tens of meters. Transient signals originating beyond the study area are also observed with amplitudes greater than some microseismic events. The wind‐related ground motions contribute to local high‐frequency seismic noise. Some of these signals may be associated with small failures of the subsurface material. During elevated wind conditions a borehole seismometer at a depth of 148 m shows increased energy in the 1–8‐Hz band that is commonly used for earthquake and tremor detection. The wind‐related earthquake‐ and tremor‐like signals should be accounted for in earthquake detection algorithms due to the similar features in both time and frequency domains. Proper recognition of wind‐related ground motions can contribute to understanding the composition of continuous seismic waveforms and characterize mechanical properties of the shallow crust.

show abstract

“…Previous studies that have attempted to spatially track water flow have documented their azimuthal distribution but not their epicentral coordinates (24)(25)(26). Location of epicentral coordinates of simultaneously active and spatially spread noise sources indeed represents a major seismological challenge (27), since it requires observations of the wave-field all around the targeted sources with high enough resolution to deal with its strong incoherency (28,29). Here, we demonstrate that well-resolved maps of subglacial drainage systems can be retrieved using particularly dense seismic arrays and by adapting the matched-field processing (MFP) technique (28) to the particularity of dealing with spatially spread sources.…”

mentioning

confidence: 99%

Observing the subglacial hydrology network and its dynamics with a dense seismic array

Nanni

Gimbert

Roux

et al. 2021

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

Subglacial water flow strongly modulates glacier basal motion, which itself strongly influences the contributions of glaciers and ice sheets to sea level rise. However, our understanding of when and where subglacial water flow enhances or impedes glacier flow is limited due to the paucity of direct observations of subglacial drainage characteristics. Here, we demonstrate that dense seismic array observations combined with an innovative systematic seismic source location technique allows the retrieval of a two-dimensional map of a subglacial drainage system, as well as its day-to-day temporal evolution. We observe with unprecedented detail when and where subglacial water flows through a cavity-like system that enhances glacier flow versus when and where water mainly flows through a channel-like system that impedes glacier flow. Most importantly, we are able to identify regions of high hydraulic connectivity within and across the cavity and channel systems, which have been identified as having a major impact on the long-term glacier response to climate warming. Applying a similar seismic monitoring strategy in other glacier settings, including for ice sheets, may help to diagnose the susceptibility of their dynamics to increased meltwater input due to climate warming.

show abstract

Matched Field Acoustics

Cited by 28 publications

References 0 publications

Basic data features and results from a spatially dense seismic array on the San Jacinto fault zone

Basic data features and results from a spatially dense seismic array on the San Jacinto fault zone

Characteristics of Ground Motion Generated by Wind Interaction With Trees, Structures, and Other Surface Obstacles

Observing the subglacial hydrology network and its dynamics with a dense seismic array

Contact Info

Product

Resources

About