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  • 1
    Publication Date: 2010-12-17
    Description: In this receiver function study, we investigate the structure of the crust beneath six seismic broadband stations close to the Sunda Arc formed by subduction of the Indo-Australian under the Sunda plate. We apply three different methods to analyse receiver functions at single stations. A recently developed algorithm determines absolute shear-wave velocities from observed frequency-dependent apparent incidence angles of P waves. Using waveform inversion of receiver functions and a modified Zhu and Kanamori algorithm, properties of discontinuities such as depth, velocity contrast, and sharpness are determined. The combination of the methods leads to robust results. The approach is validated by synthetic tests. Stations located on Malaysia show high-shear-wave velocities (VS) near the surface in the range of 3.4-3.6 km s-1 attributed to crystalline rocks and 3.6-4.0 km s-1 in the lower crust. Upper and lower crust are clearly separated, the Moho is found at normal depths of 30-34 km where it forms a sharp discontinuity at station KUM or a gradient at stations IPM and KOM. For stations close to the subduction zone (BSI, GSI and PSI) complexity within the crust is high. Near the surface low VS of 2.6-2.9 km s-1 indicate sediment layers. High VS of 4.2 km s-1 are found at depth greater than 6 and 2 km at BSI and PSI, respectively. There, the Moho is located at 37 and 40 km depth. At station GSI, situated closest to the trench, the subducting slab is imaged as a north-east dipping structure separated from the sediment layer by a 10 km wide gradient in VS between 10 and 20 km depth. Within the subducting slab VS ≈ 4. 7 km s-1. At station BSI, the subducting slab is found at depth between 90 and 110 km dipping 20° ± 8° in approximately N 60° E. A velocity increase in similar depth is indicated at station PSI, however no evidence for a dipping layer is found. © 2010 Springer Science+Business Media B.V.
    Print ISSN: 1383-4649
    Electronic ISSN: 1573-157X
    Topics: Geosciences , Physics
    Published by Springer
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  • 2
    Publication Date: 2024-02-23
    Description: Abstract
    Description: Extensive passive seismic monitoring was carried out between September 2017 and September 2018 over the Los Humeros geothermal field in Mexico. This experiment, in addition to several geophysical, geological, and geochemical surveys was conducted in the framework of the European H2020 and Mexican CONACyT-SENER project GEMex for a better understanding of the structures and behavior of the local geothermal system currently under exploitation, and for investigating future development areas. 25 broadband stations (22 Trillium C-120s and 3 Trillium C-20 PH) recording at 200 Hz, and 20 short period stations (Mark L-4C-3D) recording at 100 Hz comprised the network which is sub-divided into two sub-networks. An inner and denser (~1.6-2 km inter-station distance) pseudo-rhomboidal array (27 stations) was laid out to cover the producing zone and retrieve local seismicity mainly associated to injection and production operations, and to comply with beamforming of ambient noise and time reverse imaging techniques. An outer and sparser (~5 km minimum spacing) array was placed at around 30 km radius surrounding the inner network, and was mainly dedicated to larger scale imaging techniques, such as seismic ambient noise tomography, and regional earthquakes tomography. The GEMex project is supported by the European Union’s Horizon 2020 programme for Research and Innovation under grant agreement No 727550 and the Mexican Energy Sustainability Fund CONACYT-SENER, project 2015-04-68074. Waveform data are available from the GEOFON data centre, under network code 6G and are embargoed until Jan 2023.
    Keywords: Broadband seismic waveforms ; Seismology ; temporary local seismic experiment ; Monitoring system ; EARTH SCIENCE 〉 SOLID EARTH ; In Situ/Laboratory Instruments 〉 Magnetic/Motion Sensors 〉 Seismometers ; In Situ Land-based Platforms 〉 GEOPHYSICAL STATIONS/NETWORKS ; In Situ Land-based Platforms 〉 GEOPHYSICAL STATIONS/NETWORKS 〉 SEISMOLOGICAL STATIONS
    Type: Dataset , Seismic Network
    Format: ~1T
    Format: .mseed
    Format: XML
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