Results for the shallow structure of the broader region of Chania by HVSR measurements of ambient noise and their validation using simulation of ambient noise and independent geological information.

The city of Chania is located at the Western-North part of the island of Crete. It is mostly built over Neogene sediments of unknown thickness. In the southern part of the city the Chania basin is developed, filled mainly by Quaternary deposits overlyingthe deep Neogene sediments. In this complex geological setting, we conducted over 200 single station measurements of ambient noise, aiming to estimate the predominant frequency of the subsurface formations. The obtained results for the HVSR data show a different behavior between sites located on Neogene and Quaternarydeposits. In general, Neogene sediments show a single peak at low frequencies (below 1Hz, typically in the range 0.4-0.6Hz), indicating a very thick layer overlying the bedrock (Trypalion and Plattenkalk limestones). On the other hand, measurements at Quaternary deposits show two peaks, with the first one similar to the Neogene formations, while the second one is identified at higher frequencies, typically~0.8-4.0 Hz. Simulation of ambient noise 1-D models show a good correlation between the experimental and theoretical HVSR curves, especially when the initial model consists of two layers (typically Neogene sediments overlying high-velocity bedrock formations) with a clear identification of the lower frequency HVSR peak, while for three layered models (typically Quaternary sediments and underlying softerNeogene and Neogene/bedrock high-velocity formations) results are more complicated, although both HVSR frequencies can be partly reconstructed.

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Insecticide Resistance Patterns and Mechanisms in Aedes aegypti (Diptera: Culicidae) Populations Across Abidjan, Côte d’Ivoire Reveal Emergent Pyrethroid Resistance

Journal of Medical Entomology ◽

10.1093/jme/tjab045 ◽

2021 ◽

Author(s):

Lucien Yao Konan ◽

Welbeck Achille Oumbouke ◽

Urbain Garhapié Silué ◽

Ibrahima Zanakoungo Coulibaly ◽

Jean-Claude Tokou Ziogba ◽

...

Keyword(s):

Aedes Aegypti ◽

Cote D'ivoire ◽

Côte D’Ivoire ◽

Pyrethroid Resistance ◽

Population Based ◽

Cote D’Ivoire ◽

Low Frequencies ◽

Larval Habitats ◽

Côte D'ivoire ◽

The City

Abstract From 2008 to 2017, the city of Abidjan, Côte d’Ivoire experienced several Aedes-borne disease epidemics which required control of the vector mosquito population based on the reduction of larval habitats and insecticidal sprays for adult mosquitoes. This study was undertaken to assess the insecticide susceptibility status of Aedes aegypti (Linnaeus) in the city of Abidjan. Immature Ae. aegypti were sampled from several larval habitats within seven communes of Abidjan and reared to adults. Three to five days old F1 emerged adults were tested for susceptibility using insecticide-impregnated papers and the synergist piperonyl butoxide (PBO) following WHO bioassay guidelines. The results showed that Ae. aegypti populations from Abidjan were resistant to 0.1% propoxur, and 1% fenitrothion, with mortality rates ranging from 0% to 54.2%. Reduced susceptibility (93.4–97.5% mortality) was observed to 0.05% deltamethrin, 0.75% permethrin, 0.05% lambda-cyhalothrin, 5% malathion, and 0.8% chlorpyrifos-methyl. This reduced susceptibility varied depending on the insecticide and the collection site. The restoration of mortality when the mosquitoes were pre-exposed to the synergist PBO suggests that increased activity of oxidases could be contributing to resistance. Three kdr mutations (V410L, V1016I, and F1534C) were present in populations tested, with low frequencies for the Leu410 (0.28) and Ile1016 (0.32) alleles and high frequencies for the Cys1534 allele (0.96). These findings will be used to inform future arbovirus vector control activities in Abidjan.

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Structure of the crust and uppermost mantle beneath the Sicily channel from ambient noise and earthquake tomography

Annals of Geophysics ◽

10.4401/ag-8356 ◽

2020 ◽

Vol 63 (Vol 63 (2020)) ◽

Author(s):

Radia Kherchouche ◽

Merzouk Ouyed ◽

Abdelkrim Aoudia ◽

Billel Mellouk ◽

Ahmed Saadi

Keyword(s):

High Velocity ◽

Ambient Noise ◽

Velocity Structure ◽

Dispersion Curves ◽

Mount Etna ◽

Uppermost Mantle ◽

Velocity Models ◽

Phase Velocity Dispersion ◽

Sicily Channel ◽

Tyrrhenian Basin

• In this work, we study the crust and the uppermost mantle structure beneath the Sicily Channel, by applying the ambient noise and earthquake tomography method. After computing cross-correlation of the continuous ambient noise signals and processing the earthquake data, we extracted 104 group velocity and 68 phase velocity dispersion curves corresponding to the fundamental mode of the Rayleigh waves. We computed the average velocity of those dispersion curves to obtain tomographic maps at periods ranging from 5 s to 40 s for the group velocities and from 10 s to 70 for the phase velocities. We inverted group and phase speeds to get the shear-wave velocity structure from the surface down to 100 km depth with a lateral resolution of about 200 km. The resulted velocity models reveal a thin crust with thickness value of 15 km beneath the southern part of the Tyrrhenian basin and a thickness value of 20 km beneath Mount Etna. The obtained thickness values are well correlated with the reported extension of the Tyrrhenian lithosphere due to the past earthquake tomography subduction and rollback of the Ionian slab beneath the Calabrian Arc. The crustal thickness increases and reaches values between 28 and 30 km beneath the Tunisian coasts and Sicily Channel. The S-wave models reveal also the presence of high velocity body beneath the island of Sicily. This finding can be interpreted as the presence of the Ionian slab subducting beneath the Calabrian Arc. Another high velocity body is observed beneath the southern part of the Tyrrhenian basin, it might be interpreted as the presence of fragments of the African continental lithosphere beneath the Tyrrhenian basin.

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Fast Determination of Earthquake Depth Using Seismic Records of a Single Station, Implementing Machine Learning Techniques

Ingeniería e Investigación ◽

10.15446/ing.investig.v38n2.68407 ◽

2018 ◽

Vol 38 (2) ◽

pp. 91-103 ◽

Cited By ~ 2

Author(s):

Luis Hernán Ochoa Gutierrez ◽

Luis Fernando Niño Vasquez ◽

Carlos Alberto Vargas Jimenez

Keyword(s):

Warning System ◽

Machine Learning Techniques ◽

Support Vector ◽

Fast Determination ◽

Learning Techniques ◽

Single Station ◽

Time Signals ◽

Seismic Records ◽

The City

The purpose of this research is to apply a new approach to make a fast determination of earthquake depth using seismic records of the “El Rosal” station, near to the city of Bogota – Colombia, by applying support vector machine regression (SVMR). The algorithm was trained with descriptors obtained from time signals of 863 seismic events acquired between January 1998 and October 2008; only earthquakes with magnitude ≥ 2 were contemplated, filtering its signals to remove diverse kind of noises not related to earth tremors. During training stages of SVMR several combinations of kernel function exponent and complexity factor were considered for time signals of 5, 10 and 15 seconds along with earthquake magnitudes of 2.0, 2.5, 3.0 and 3.5 (Ml). The best classification of SVMR was obtained using time signals of 15 seconds and earthquake magnitudes of 3.5 with kernel exponent of 10 and complexity factor of 2, showing accuracy of 0.6 ± 16.5 kilometers, which is good enough to be used in an early warning system for the city of Bogota. It is recommended to provide this model with a previous phase of deep-shallow classification.

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Learning to cope: vocal adjustment to urban noise is correlated with prior experience in black-capped chickadees

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2016.1058 ◽

2016 ◽

Vol 283 (1833) ◽

pp. 20161058 ◽

Cited By ~ 31

Author(s):

Stefanie E. LaZerte ◽

Hans Slabbekoorn ◽

Ken A. Otter

Keyword(s):

Ambient Noise ◽

Prior Experience ◽

Traffic Noise ◽

Experimental Studies ◽

Previous Exposure ◽

Poecile Atricapillus ◽

Urban Noise ◽

Experimental Noise ◽

Avian Communication ◽

The City

Urban noise can interfere with avian communication through masking, but birds can reduce this interference by altering their vocalizations. Although several experimental studies indicate that birds can rapidly change their vocalizations in response to sudden increases in ambient noise, none have investigated whether this is a learned response that depends on previous exposure. Black-capped chickadees ( Poecile atricapillus ) change the frequency of their songs in response to both fluctuating traffic noise and experimental noise. We investigated whether these responses to fluctuating noise depend on familiarity with noise. We confirmed that males in noisy areas sang higher-frequency songs than those in quiet areas, but found that only males in already-noisy territories shifted songs upwards in immediate response to experimental noise. Unexpectedly, males in more quiet territories shifted songs downwards in response to experimental noise. These results suggest that chickadees may require prior experience with fluctuating noise to adjust vocalizations in such a way as to minimize masking. Thus, learning to cope may be an important part of adjusting to acoustic life in the city.

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Wind dependence of deep ocean ambient noise at low frequencies

The Journal of the Acoustical Society of America ◽

10.1121/1.405440 ◽

1993 ◽

Vol 93 (2) ◽

pp. 782-789 ◽

Cited By ~ 31

Author(s):

N. R. Chapman ◽

J. W. Cornish

Keyword(s):

Ambient Noise ◽

Deep Ocean ◽

Low Frequencies

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Multiple geophysical investigations to characterize massive slope failure deposits: application to the Balta rockslide, Carpathians

Geophysical Journal International ◽

10.1093/gji/ggab028 ◽

2021 ◽

Vol 225 (2) ◽

pp. 1032-1047

Author(s):

A-S Mreyen ◽

L Cauchie ◽

M Micu ◽

A Onaca ◽

H-B Havenith

Keyword(s):

Surface Wave ◽

Ambient Noise ◽

Slope Failure ◽

Seismic Refraction ◽

P Wave ◽

Surface Wave Dispersion ◽

Seismic Region ◽

Valley Bottom ◽

Single Station ◽

Landslide Body

SUMMARY Origins of ancient rockslides in seismic regions can be controversial and must not necessarily be seismic. Certain slope morphologies hint at a possible coseismic development, though further analyses are required to better comprehend their failure history, such as modelling the slope in its pre-failure state and failure development in static and dynamic conditions. To this effect, a geophysical characterization of the landslide body is crucial to estimate the possible failure history of the slope. The Balta rockslide analysed in this paper is located in the seismic region of Vrancea-Buzau, Romanian Carpathian Mountains and presents a deep detachment scarp as well as a massive body of landslide deposits. We applied several geophysical techniques on the landslide body, as well as on the mountain crest above the detachment scarp, in order to characterize the fractured rock material as well as the dimension of failure. Electrical resistivity measurements revealed a possible trend of increasing fragmentation of rockslide material towards the valley bottom, accompanied by increasing soil moisture. Several seismic refraction surveys were performed on the deposits and analysed in form of P-wave refraction tomographies as well as surface waves, allowing to quantify elastic parameters of rock. In addition, a seismic array was installed close to the detachment scarp to analyse the surface wave dispersion properties from seismic ambient noise; the latter was analysed together with a colocated active surface wave analysis survey. Single-station ambient noise measurements completed all over the slope and deposits were used to further reveal impedance contrasts of the fragmented material over in situ rock, representing an important parameter to estimate the depth of the shearing horizon at several locations of the study area. The combined methods allowed the detection of a profound contrast of 70–90 m, supposedly associated with the maximum landslide material thickness. The entirety of geophysical results was used as basis to build up a geomodel of the rockslide, allowing to estimate the geometry and volume of the failed mass, that is, approximately 28.5–33.5 million m3.

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Integration of ambient noise and ERT data to investigate the structure of the Yang Jia Gou rock avalanche deposits (Sichuan - China)

10.5194/egusphere-egu21-4578 ◽

2021 ◽

Author(s):

Paola Capone ◽

Vincenzo Del Gaudio ◽

Janusz Wasowski ◽

Wei Hu ◽

Nicola Venisti ◽

...

Keyword(s):

Mechanical Properties ◽

Rayleigh Waves ◽

Ambient Noise ◽

Noise Analysis ◽

Rock Avalanche ◽

Landslide Dam ◽

Mountainous Area ◽

The Tibetan Plateau ◽

Large Variability ◽

Single Station

On 12 May 2008, the mountainous area of Longmenshan, which separates the Tibetan Plateau from the Sichuan Basin, was hit by the 8.0 Ms Wenchuan earthquake which triggered about 200,000 landslides, some of which caused river damming with the formation of temporary lakes. Failures of the landslide dams can induce severe flooding downstream, therefore, it is important to study their structure and mechanical properties in order to evaluate their stability conditions.The present study investigates the landslide dam deposits of a rock avalanche triggered in Yang Jia Gou, in Sichuan Province, using single-station three component recordings of ambient noise, with the aim of obtaining information about thickness and mechanical properties of the deposits from their resonance properties. Three noise measurement campaigns and two ERT surveys were conducted to support data interpretation. The data were analyzed using the traditional Nakamura&#8217;s technique, HVNR, and the innovative technique HVIP, both based on the calculation of ratios between horizontal and vertical amplitude of ground motion. Both methods revealed the presence &#160;of resonance peaks, a major one at lower frequency, and a minor one at higher frequencies, representative of the deposit layering. HVNR showed a considerable instability in terms of amplitude of H/V, likely because this technique analyzes the entire noise wave field recorded, so to be subject to a large variability related to a variable composition of the noise field. This problem does not affect the HVIP method, which is based on the analysis of the ellipticity of Rayleigh waves, isolated from the recording.Rayleigh wave ellipticity curves were used as targets in the inversion phase to obtain the velocity profile of the site. The subsoil model was &#160;constrained by the data derived from the resistivity profiles. The results revealed: &#160;different velocity layers inside the deposit; lateral variations in thickness, in accordance with the higher frequency peak, and in mechanical properties, with an increase of stiffness, probably due to a major portion of rocky blocks; an increase in thickness of the entire deposit, probably because of the irregularities of the substrate.Further investigations are in progress through other kinds of noise analysis exploiting the synchronization of simultaneous recordings. This can provide additional constraints (to be derived from the dispersion of group velocity of Rayleigh waves) and aid resolving interpretation ambiguities.

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Single Station Ambient Noise Observations in Tehran

74th EAGE Conference and Exhibition incorporating EUROPEC 2012 ◽

10.3997/2214-4609.20148932 ◽

2012 ◽

Author(s):

M. Fotouhimehr ◽

E. Shabani ◽

N. Mirzaei ◽

E. Haghshenas

Keyword(s):

Ambient Noise ◽

Single Station

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Contribution for seismic hazard assessment with local scale focus on Durrës (Albania) and damage observation after the ML 5.4, 21st September 2019 earthquake

10.5194/egusphere-egu2020-19528 ◽

2020 ◽

Author(s):

Marco Mancini ◽

Iolanda Gaudiosi ◽

Redi Muci ◽

Maurizio Simionato ◽

Klodian Skrame

Keyword(s):

Seismic Hazard ◽

Cultural Heritage ◽

Ground Motion ◽

Seismic Risk ◽

Preliminary Results ◽

Joint Research Project ◽

Single Station ◽

Noise Measurements ◽

The City ◽

2D Array

The city of Durr&#235;s was recentely struck by a Mw 6.2 mainshock event (http://cnt.rm.ingv.it/event/23487611) that caused considerable damage and 51 victims. The city is located on an actively seismotectonic belt where seismic catalogues report few past events with magnitude higher than 6.Surface geology is generally considered to influence the ground motion recorded on site. The analysis of the influence of local effects on seismic response at ground surface appears relevant also considering that Durr&#235;s is a densely populated city prone to high seismic risk and is characterized by several important archeological and cultural heritage sites.Preliminary results obtained from recent geophysical in-situ measurements and geological surveys, carried out in Durr&#235;s after the ML 5.4, 21st September 2019 event, are presented with the aim of providing new elements for the assessment of local seismic hazard and following a comprehensive approach to the modifications induced by the site.Twenty-nine single-station noise measurements, processed through the HVSR technique, two MASW surveys and two 2D array measurements were performed. Results from noise measurements define a zone eastward of the historical centre, where the characteristics of surficial soil layers are responsible for modification to the seismic demand. In particular, HVSR curves in this area show amplification higher than 4 at a period higher than 1s. Moreover, on this location a surface waves-velocity profile obtained from a joint inversion of Rayleigh curves from MASW and 2D array with ellipticity individuates a class D soil, EC8 sensu, corresponding to marshy soil of very poor geotechnical quality. These data may be considered as key elements in the site-specific response analyses, i.e. realized according to the international codes (EC8, NEHRP), which allow to quantify the expected ground motion. These results are potentially useful for &#160;correlating&#160; construction typologies and period vibration of the buildings with the site amplification.In addition, a damage survey was carried out in one of the most damaged zones after the 21st September 2019 earthquake. Because of the following stronger event of the 26th November 2019, we think that these preliminary results may provide useful information for the post-earthquake reconstruction and enhancement of the urban resilience.&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; The activities are carried out wihin the framework of the CNR/MOES Joint research project &#8220;Seismic risk assessment in cultural heritage cities of Albania&#8221; in the biennium 2018-2019 (https://www.cnr.it/en/bilateral-agreements/agreement/60/moes-ministry-of-education-and-sport-of-the-republic-of-albania).

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Volcano Ambient Noise Interferometry in the Caribbean (VANIC)

10.5194/egusphere-egu2020-6058 ◽

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

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 &#8220;Transnational Access (TA)&#8221; 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.

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