Broadband Seismic Noise Analysis of the Himalayan Nepal Tibet Seismic Experiment

2005 ◽  
Vol 95 (3) ◽  
pp. 1202-1208 ◽  
Author(s):  
T. L. de la Torre
Keyword(s):  
Seismic Noise ◽  
Noise Analysis ◽  
Seismic Experiment

scholarly journals Ambient Seismic Noise Analysis Associated with the 2010 Eruption of Merapi Volcano Using Temporal Variations of Randomness and Background Noise

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Afif Rakhman ◽  
Wahyudi ◽  
Agus Budi Santoso ◽  
Hanik Humaida ◽  
Wiwit Suryanto
Keyword(s):  
Background Noise ◽  
Seismic Noise ◽  
Noise Analysis ◽  
Temporal Variations ◽  
Permutation Entropy ◽  
Merapi Volcano ◽  
Frequency Bands ◽  
Volcano Eruption ◽  
Power Spectral ◽  
Short Period

We present the combination of permutation entropy (PE) and power spectral density (PSD) analysis on continuous seismic data recorded by short-period seismic stations during the 2010 Merapi volcano eruption. The calculation of PE aims at characterizing the randomness level in seismic noise, while the PSD parameters use to detect the background noise level in various frequency bands. It was previously observed that a significant reduction of randomness before the volcano eruption could be indicated as one of the short-term precursors due to the lack of high frequencies (>1 Hz) in the noise wave-field caused by high absorption losses as the hot magma uprises to the upper crust. The results show no significant reduction in signal randomness before the eruption series. The characteristic of events during the preeruptive period and the crisis tends to be chaotic (PE in the range 0.9 to 1). Further calculations show that the standard deviation in PE decreased in four days before the first eruption onset on 26 October. PE was stable at the highest values (very close to 1) and gradually returned to the previous fluctuation after the eruption onset. The level of background noise in the low- and high-frequency bands appeared to have the same tendency. The two main eruptions correspond to the two highest peaks of noise levels.

Investigating Spatio-temporal Changes in Subglacial Hydrology from Dense Array Seismology.

2020 ◽  
Author(s):  
Ugo Nanni ◽  
Florent Gimbert ◽  
Philippe Roux ◽  
Albanne Lecointre
Keyword(s):  
Water Flow ◽  
Seismic Noise ◽  
Water Pressure ◽  
Noise Analysis ◽  
Drainage System ◽  
Dense Array ◽  
Noise Sources ◽  
Spatio Temporal ◽  
Surrounding Areas ◽  
Subglacial Drainage

<p>Subglacial hydrology strongly modulates glacier basal sliding, and thus likely exerts a major control on ice loss and sea-level rise. However, the limited direct and spatialized observations of the subglacial drainage system make difficult to assess the physical processes involved in its development. Recent work shows that detectable seismic noise is generated by subglacial water flow, such that seismic noise analysis may be used to retrieve the physical properties of subglacial channelized water flow. Yet, investigating the spatial organisation of the drainage system (e.g. channels numbers and positions) together with its evolving properties (e.g. pressure conditions) through seismic observations remains to be done. The objective of this study is to bring new insights on the subglacial hydrology spatio-temporal dynamics using dense array seismic observations.</p><p>We use 1-month long ground motion records at a hundred of sensors deployed on the Argentière Glacier (French Alps) during the onset of the melt season, when the subglacial drainage system is expected to strongly evolve in response to the rapidly increasing water input. We conduct a multi-method approach based on the analysis of both amplitude and phase maps of seismic signals. We observe characteristic spatial patterns, consistent across those independent approaches, which we attribute to the underlying subglacial drainage system.</p><p>The phase-driven approach shows seismic noise sources that focuses in the along-flow direction as the water input increases. We identify this evolution as the development of the main subglacial channel whose position is coherent with the one expected from hydraulic potential calculations. During periods of rapid changes in water input (5 days over 31) and concomitant glacier acceleration the amplitude-driven approach shows spatial pattern highly consistent with the seismic noise sources location. At this time, we suggest that the spatial variations in the amplitude are representative of the water pressure conditions in subglacial channels and surrounding areas. Our spatialized observations therefore reveal the spatio-temporal evolution of the subglacial drainage system together with its changing pressure conditions. We observe, for instance, that channels develop at the very onset of the melt-season and rapidly capture the water from surrounding areas. Such unique observations may allow to better constrain the physics of subglacial water flow and therefore strengthen our knowledge on the dynamics of subglacial environments.</p>

Ambient Seismic Noise Analysis from Array and Borehole Networks in Svalbard, Norway

2014 ◽  
Author(s):  
J. Albaric ◽  
G. Hillers ◽  
D. Kuehn ◽  
D. Harris ◽  
F. Brenguier ◽  
...  
Keyword(s):  
Seismic Noise ◽  
Noise Analysis ◽  
Ambient Seismic Noise

Bandung seismic experiment: Towards tomographic imaging by using ambient seismic noise

2016 ◽  
Author(s):  
Bayu Pranata ◽  
Tedy Yudistira ◽  
Erdinc Saygin ◽  
Phil R. Cummins ◽  
Sri Widiyantoro ◽  
...  
Keyword(s):  
Seismic Noise ◽  
Tomographic Imaging ◽  
Ambient Seismic Noise ◽  
Seismic Experiment

scholarly journals On the predictability of volcano-tectonic events by low frequency seismic noise analysis at Teide-Pico Viejo volcanic complex, Canary Islands

2006 ◽  
Vol 6 (3) ◽  
pp. 365-376 ◽  
Author(s):  
M. Tárraga ◽  
R. Carniel ◽  
R. Ortiz ◽  
J. M. Marrero ◽  
A. García
Keyword(s):  
Canary Islands ◽  
Seismic Noise ◽  
Noise Analysis ◽  
Low Frequency ◽  
Seismic Events ◽  
Volcanic Complex ◽  
Main Concern ◽  
Forecast Method ◽  
Volcanic Origin ◽  
Strombolian Eruption

Abstract. The island of Tenerife (Canary Islands, Spain), is showing possible signs of reawakening after its last basaltic strombolian eruption, dated 1909 at Chinyero. The main concern relates to the central active volcanic complex Teide - Pico Viejo, which poses serious hazards to the properties and population of the island of Tenerife (Canary Islands, Spain), and which has erupted several times during the last 5000 years, including a subplinian phonolitic eruption (Montaña Blanca) about 2000 years ago. In this paper we show the presence of low frequency seismic noise which possibly includes tremor of volcanic origin and we investigate the feasibility of using it to forecast, via the material failure forecast method, the time of occurrence of discrete events that could be called Volcano-Tectonic or simply Tectonic (i.e. non volcanic) on the basis of their relationship to volcanic activity. In order to avoid subjectivity in the forecast procedure, an automatic program has been developed to generate forecasts, validated by Bayes theorem. A parameter called "forecast gain" measures (and for the first time quantitatively) what is gained in probabilistic terms by applying the (automatic) failure forecast method. The clear correlation between the obtained forecasts and the occurrence of (Volcano-)Tectonic seismic events - a clear indication of a relationship between the continuous seismic noise and the discrete seismic events - is the explanation for the high value of this "forecast gain" in both 2004 and 2005 and an indication that the events are Volcano-Tectonic rather than purely Tectonic.

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