Erratum: Combined Automated and Off-line Computer Processing System for Seismic Monitoring with Small Aperture Arrays

1998 ◽  
Vol 69 (5) ◽  
pp. 405-405
Author(s):  
L. M. Haikin ◽  
A. F. Kushnir ◽  
A. M. Dainty
Keyword(s):  
Processing System ◽  
Seismic Monitoring ◽  
Computer Processing ◽  
Small Aperture ◽  
Aperture Arrays

Detection and source parameterization of small-energy fireball events in Western Alps with ground-based infrasonic arrays

2021 ◽  
Author(s):  
Giacomo Belli ◽  
Emanuele Pace ◽  
Emanuele Marchetti
Keyword(s):  
Western Alps ◽  
Apparent Velocity ◽  
Array Analysis ◽  
Small Energy ◽  
Small Aperture ◽  
Energy Estimation ◽  
Trajectory Reconstruction ◽  
Tnt Equivalent ◽  
Back Azimuth ◽  
Aperture Arrays

Summary We present infrasound signals generated by four fireball events occurred in Western Alps between 2016 and 2019 and that were recorded by small aperture arrays at source-to receiver distances < 300 km. Signals consist in a series of short-lived infrasonic arrivals that are closely spaced in time. Each arrival is identified as a cluster of detections with constant wave parameters (back-azimuth and apparent velocity), that change however from cluster to cluster. These arrivals are likely generated by multiple infrasonic sources (fragmentations or hypersonic flow) along the entry trajectory. We developed a method, based on 2D ray-tracing and on the independent optically determined time of the event, to locate the source position of the multiple arrivals from a single infrasonic array data and to reconstruct the 3D trajectory of a meteoroid in the Earth's atmosphere. The trajectories derived from infrasound array analysis are in excellent agreement with trajectories reconstructed from eyewitnesses reports for the four fireballs. Results suggest that the trajectory reconstruction is possible for meteoroid entries located up to ∼300 km from the array, with an accuracy that depends on the source-to-receiver distance and on the signal-to-noise level. We also estimate the energy of the four fireballs using three different empirical laws, based both on period and amplitude of recorded infrasonic signals, and discuss their applicability for the energy estimation of small energy fireball events ($\le 1{\rm{kt\,\,TNT\,\,equivalent}}$).

Matched-field source localization with multiple small-aperture arrays

2015 ◽  
Vol 138 (3) ◽  
pp. 1754-1754 ◽  
Author(s):  
Dag Tollefsen ◽  
Stan E. Dosso
Keyword(s):  
Source Localization ◽  
Small Aperture ◽  
Field Source ◽  
Aperture Arrays

Computer Processing of Routine Psychiatric Records

1966 ◽  
Vol 05 (01) ◽  
pp. 25-30 ◽  
Author(s):  
A. Richman
Keyword(s):  
Medical Records ◽  
Reporting System ◽  
Processing System ◽  
Computer Processing ◽  
Manual Processing

The feasibility of computer processing of routine medical records is described. This can be done centrally with existing computer facilities. In the peripheral component of a reporting system, an efficient manual processing system can be provided by use of the PABLUM-1 system.

A seismic passive imaging step beyond SPAC and ReMi

Geophysics ◽  
2013 ◽  
Vol 78 (5) ◽  
pp. KS63-KS72 ◽  
Author(s):  
Francesco Mulargia ◽  
Silvia Castellaro
Keyword(s):  
Passive Imaging ◽  
Small Aperture ◽  
Simple Geometry ◽  
Recording Station ◽  
Refraction Microtremor ◽  
A New Technique ◽  
Statistical Mode ◽  
The One ◽  
Aperture Arrays ◽  
The Waves

The basic property of passive imaging is that, given any two points, one of them can be taken as the source of the waves and the other as the recording station. This property can be derived from the statistical self-alignment of the rays along the vector joining the two points, and applies also to nondiffuse wavefields like seismic tremor. It provides a statistical basis for the use of the stationary phase integral, allowing passive interferometry under the mild constraint of mechanical homogeneity at a local scale. Combined with the tremor’s large spectral bandwidth, it allows one to recover the local Green’s function from spatial correlation. Furthermore, combining this property also with the azimuthal isotropy of either the wavefield or the array, and using the statistical mode as the estimator, provides a new technique to measure the local velocity dispersion in the subsoil. This technique exploits the potential of spatial autocorrelation (SPAC) and refraction microtremor (ReMi), allowing one (1) to use sparse small-aperture arrays with simple geometry, (2) to dispense with the fitting of Bessel functions, and (3) to measure, in a few minutes, the local (phase and group) wave velocity as a function of frequency of potentially all the wave-propagation modes — body and surface — and not just of the one prevailing at each frequency.

Bayesian hierarchical model for variations in earthquake peak ground acceleration within small-aperture arrays

2018 ◽  
Vol 29 (3) ◽  
pp. e2497 ◽  
Author(s):  
Sahar Rahpeyma ◽  
Benedikt Halldorsson ◽  
Birgir Hrafnkelsson ◽  
Sigurjón Jónsson
Keyword(s):  
Hierarchical Model ◽  
Peak Ground Acceleration ◽  
Bayesian Hierarchical Model ◽  
Ground Acceleration ◽  
Small Aperture ◽  
Bayesian Hierarchical ◽  
Aperture Arrays

Picking versus stacking in a modern microearthquake location: Comparison of results from a surface passive seismic monitoring array in Oklahoma

Geophysics ◽  
2014 ◽  
Vol 79 (6) ◽  
pp. KS61-KS68 ◽  
Author(s):  
Jeremy D. Pesicek ◽  
Duncan Child ◽  
Brad Artman ◽  
Konrad Cieślik
Keyword(s):  
Monitoring Network ◽  
Seismic Monitoring ◽  
Precise Determination ◽  
Double Difference ◽  
Spatial And Temporal Patterns ◽  
Small Aperture ◽  
Event Location ◽  
Passive Seismic ◽  
Velocity Information ◽  
Favorable Conditions

We present location results for a group of [Formula: see text] microearthquakes that occurred in 2012 in a region of Oklahoma hosting ongoing exploration activities. Using a local passive surface seismic monitoring network of 15 broadband stations, we applied two modern location techniques that use fundamentally different approaches. The first is a pick-based double-difference relocation method with waveform crosscorrelation. Multiple-event location techniques such as these are generally regarded as the best approach for obtaining high-precision locations from pick data. The second approach is an automated waveform migration stacking method. These types of methods are becoming increasingly common due to increasing network station density and computer power. The results from the two methods show excellent agreement and provide similar results for the interpreter. Both methods reveal spatial and temporal patterns in the locations that are not visible in results obtained using a more traditional pick-based approach. We performed two statistical uncertainty tests to assess the effects of data quality and quantity on the two methods. We show that the uncertainties for both methods are comparable, but that the stack-based locations are less sensitive to station geometry, likely due to the different treatment of outliers and the beneficial inclusion of noisier data. Finally, we discuss the favorable conditions in which to apply each method and argue that for small aperture surface arrays where accurate velocity information exists, such as in this study, the stack-based method is preferable due to the higher degree of automation. Under these conditions, stack-based methods better allow for rapid and precise determination of microearthquake locations, facilitating improved interpretations of seismogenic processes.

DONAR: a computer processing system to extend ultrasonic pulse-echo testing

Ultrasonics ◽  
1973 ◽  
Vol 11 (4) ◽  
pp. 165-173 ◽  
Author(s):  
S. Lees ◽  
F.B. Gerhard ◽  
F.E. Barber ◽  
S.P. Cheney
Keyword(s):  
Processing System ◽  
Ultrasonic Pulse ◽  
Computer Processing ◽  
Pulse Echo
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