Lithospheric structure of the Pannonian Basin using Rayleigh wave ambient noise tomography – preliminary results

2020 ◽  
Author(s):  
Máté Timkó ◽  
Lars Wiesenberg ◽  
Amr El-Sharkawy ◽  
Zoltán Wéber ◽  
Thomas Meier ◽  
...  
Keyword(s):  
Phase Velocity ◽  
Rayleigh Wave ◽  
Ambient Noise ◽  
Velocity Structure ◽  
Pannonian Basin ◽  
Vertical Component ◽  
Ambient Noise Tomography ◽  
Crust And Upper Mantle ◽  
Mountain Chain ◽  
One Year

<p>We used Rayleigh wave ambient noise tomography to investigate the crust and uppermost mantle structure of the Pannonian Basin. The Pannonian Basin and the surrounding orogens are located within the arcuate Alpine–Carpathian mountain chain in Central Europe. It is a back-arc basin characterized by a thinned lower crust and an updoming mantle. Benath the basin both the crust and the lithosphere have smaller thickness than the continental average. Imaging the velocity structure of the crust and upper mantle may help us to better understand the structure and formation of the Carpathian–Pannonian region.</p><p>We used data from the permanent seismological stations of the broader Central European region together with the AlpArray Seismic Network (AASN) and analysed one-year seismic data from 2017. More than 18 thousand vertical component noise cross-correlation functions were calculated and Rayleigh wave inter-station phase velocity curves were determined using an automated measuring algorithm. Anisotropic phase velocity tomographic imaging were carried out for the whole Pannonian Basin between 2 and 40s periods (~5-60 km).</p><p>The locations of the retrieved phase-velocity anomalies consistent with the well-known geologic and tectonic structure of the area (deep basins and orogenic belts) and are comparable to recent tomographic models published in the literature.</p>

Crustal and upper mantle velocity structure of the Pannonian Region using Rayleigh wave ambient noise tomography

2021 ◽  
Author(s):  
Máté Timkó ◽  
Lars Wiesenberg ◽  
Amr El-Sharkawy ◽  
Zoltán Wéber ◽  
Thomas Meier ◽  
...  
Keyword(s):  
Rayleigh Wave ◽  
Ambient Noise ◽  
Velocity Structure ◽  
Pannonian Basin ◽  
Vertical Component ◽  
High Heat ◽  
Moho Depth ◽  
Ambient Noise Tomography ◽  
Period Range ◽  
Waveform Data

<p>The Pannonian Basin is located in Central-Europe surrounded by the Alpine, Carpathian, and Dinarides mountain ranges. This is a back-arc basin characterized by shallow Moho depth, updoming mantle and high heat flow. In this study, we present the results of the Rayleigh wave based ambient noise tomography to investigate the velocity structure of the Carpathian-Pannonian region. </p><p>For the ambient noise measurements, we collected the continuous waveform data from more than 1280 seismological stations from the broader Central-Eastern European region. This dataset embraces all the permanent and the temporary (AlpArray, PASSEQ, CBP, SCP) stations from the 9-degree radius of the Pannonian Basin which were operating between the time period between 2005 and 2018. All the possible vertical component noise cross-correlation functions were calculated and all phase velocity curves were determined in the 5-80 s period range using an automated measuring algorithm. </p><p>The collected dispersion measurements were then used to create tomographic images that are characterized by similar velocity anomalies in amplitude, pattern and location that are consistent with the well-known tectonic and geologic structure of the research area and are comparable to previous tomographic models published in the literature.</p>

scholarly journals Upper-plate structure in Ecuador coincident with the subduction of the Carnegie Ridge and the southern extent of large mega-thrust earthquakes

2019 ◽  
Vol 220 (3) ◽  
pp. 1965-1977 ◽  
Author(s):  
Colton Lynner ◽  
Clinton Koch ◽  
Susan L Beck ◽  
Anne Meltzer ◽  
Lillian Soto-Cordero ◽  
...  
Keyword(s):  
Ambient Noise ◽  
Velocity Structure ◽  
Sedimentary Basins ◽  
Past Century ◽  
Ambient Noise Tomography ◽  
Plate Interface ◽  
Crust And Upper Mantle ◽  
Southern Boundary ◽  
Plate Structure ◽  
Velocity Anomaly

SUMMARY The Ecuadorian convergent margin has experienced many large mega-thrust earthquakes in the past century, beginning with a 1906 event that propagated along as much as 500 km of the plate interface. Many subsections of the 1906 rupture area have subsequently produced Mw ≥ 7.7 events, culminating in the 16 April 2016, Mw 7.8 Pedernales earthquake. Interestingly, no large historic events Mw ≥ 7.7 appear to have propagated southward of ∼1°S, which coincides with the subduction of the Carnegie Ridge. We combine data from temporary seismic stations deployed following the Pedernales earthquake with data recorded by the permanent stations of the Ecuadorian national seismic network to discern the velocity structure of the Ecuadorian forearc and Cordillera using ambient noise tomography. Ambient noise tomography extracts Vsv information from the ambient noise wavefield and provides detailed constraints on velocity structures in the crust and upper mantle. In the upper 10 km of the Ecuadorian forearc, we see evidence of the deepest portions of the sedimentary basins in the region, the Progreso and Manabí basins. At depths below 30 km, we observe a sharp delineation between accreted fast forearc terranes and the thick crust of the Ecuadorian Andes. At depths ∼20 km, we see a strong fast velocity anomaly that coincides with the subducting Carnegie Ridge as well as the southern boundary of large mega-thrust earthquakes. Our observations raise the possibility that upper-plate structure, in addition to the subducting Carnegie Ridge, plays a role in the large event segmentation seen along the Ecuadorian margin.

scholarly journals High-resolution 3D shallow crustal structure in Long Beach, California: Application of ambient noise tomography on a dense seismic array

Geophysics ◽  
2013 ◽  
Vol 78 (4) ◽  
pp. Q45-Q56 ◽  
Author(s):  
Fan-Chi Lin ◽  
Dunzhu Li ◽  
Robert W. Clayton ◽  
Dan Hollis
Keyword(s):  
Phase Velocity ◽  
Ambient Noise ◽  
Velocity Structure ◽  
Shear Velocity ◽  
Seismic Array ◽  
Clear Correlation ◽  
Long Beach ◽  
Ambient Noise Tomography ◽  
Station Pair ◽  
Dense Seismic Array

Ambient noise tomography has proven to be effective in resolving shallow earth structure. We applied ambient noise tomography on a dense seismic array in Long Beach, California. The array was composed of more than 5200 stations with an average spacing close to 100 m. Three weeks of passive ambient noise were crosscorrelated between each station pair, which resulted in more than 13.5 million crosscorrelations within the area. Clear fundamental-mode Rayleigh waves were observed between 0.5 and 4 Hz, which were most sensitive to structure above 1-km depth. For each station pair, we applied frequency-time analysis to determine the phase traveltime dispersion, and, for each frequency, we applied eikonal tomography to determine the Rayleigh wave phase velocity map. The eikonal tomography accounted for ray bending by tracking the wavefront and allowed uncertainties to be estimated through statistical analysis. The compilation of phase velocity maps was then used to invert for 3D shear velocity structure. The inverted model showed clear correlation with the known geologic features such as the shallow south–north velocity dichotomy and a deeper fast anomaly associated with the Newport-Inglewood fault zone. Our results can potentially be used to complement traditional active source studies.

scholarly journals Crust and upper mantle structure of the Ligurian Sea revealed by ambient noise tomography using ocean bottom seismometer data

2020 ◽  
Author(s):  
Felix Noah Wolf ◽  
Dietrich Lange ◽  
Heidrun Kopp ◽  
Anke Dannowski ◽  
Ingo Grevemeyer ◽  
...  
Keyword(s):  
Phase Velocity ◽  
Ambient Noise ◽  
Cross Correlation ◽  
Velocity Structure ◽  
Signal To Noise Ratio ◽  
Time Windows ◽  
Ocean Bottom ◽  
Ocean Bottom Seismometer ◽  
Ligurian Sea ◽  
Crust And Upper Mantle

<p>The Liguro-Provencal-basin was formed as a back-arc basin of the retreating Calabrian-Apennines subduction zone during the Oligocene and Miocene. The resulting rotation of the Corsica-Sardinia block at roughly 32–24 Ma is associated with rifting, shaping the Ligurian Sea. It is highly debated though, whether oceanic or atypical oceanic crust was formed or if the crust is continental and experienced extreme thinning during the opening of the basin.</p><p>To investigate the velocity structure of the Ligurian Sea a network (LOBSTER) of 29 broadband Ocean Bottom Seismometer (OBS) was installed jointly by GEOMAR (Germany) and ISTerre (France). The LOBSTER array measured continuously for eight months between June 2017 and February 2018 and is part of the AlpArray seismic network. AlpArray is a European initiative to further reveal the geophysical and geological properties of the greater Alpine area.</p><p>We contribute to the debate by surveying the type of crust and lithosphere flooring the Ligurian Sea.<br>Because of additional noise sources in the ocean, causing instrument tilt or seafloor compliance, OBS data are rarely used for ambient noise studies. However, we extensively pre-process the data to improve the signal-to-noise ratio. Then, we calculate daily cross-correlation functions for the LOBSTER array and surrounding land stations. Additionally, we correlate short time windows that include strong events. The cross-correlations of these are dominated by earthquake signals and allow us to derive surface wave group velocities for longer periods than using ambient noise only. Finally, phase velocity maps are obtained by inverting Green’s functions derived from cross-correlation of ambient noise and teleseismic events, respectively. The phase velocity maps show strong heterogeneities for short periods (5-15 s, corresponding to shallow depths). Causes for these include varying sediment thickness, fault zones and magmatism. For longer periods (20-80 s) the velocity structure smoothens and reveals mantle velocities north-northwest of the basin centre. This might hint on an asymmetric opening of the basin. We do not see strong indications for an oceanic spreading centre in the Ligurian basin.</p>

Sign in / Sign up

Export Citation Format

Share Document