Abstract Laser interferometry enables to remotely measure microscopical length changes of deployed telecommunication cables originating from earthquakes. Long reach and compatibility with data ...transmission make it attractive for the exploration of both remote regions and highly-populated areas where optical networks are pervasive. However, interpretation of its response still suffers from a limited number of available datasets. We systematically analyze 1.5 years of acquisitions on a land-based telecommunication cable in comparison to co-located seismometers, with successful detection of events in a broad magnitude range, including very weak ones. We determine relations between a cable’s detection probability and the events magnitude and distance, introducing spectral analysis of fiber data as a tool to investigate earthquake dynamics. Our results reveal that quantitative analysis is possible, confirming applicability of this technique both for the global monitoring of our planet and the daily seismicity monitoring of populated areas, in perspective exploitable for civilian protection.
SUMMARY
We infer seismic azimuthal anisotropy from ambient-noise-derived Rayleigh waves in the wider Vienna Basin region. Cross-correlations of the ambient seismic field are computed for 1953 station ...pairs and periods from 5 to 25 s to measure the directional dependence of interstation Rayleigh-wave group velocities. We perform the analysis for each period on the whole data set, as well as in overlapping 2°-cells to regionalize the measurements, to study expected effects from isotropic structure, and isotropic–anisotropic trade-offs. To extract azimuthal anisotropy that relates to the anisotropic structure of the Earth, we analyse the group velocity residuals after isotropic inversion. The periods discussed in this study (5–20 s) are sensitive to crustal structure, and they allow us to gain insight into two distinct mechanisms that result in fast orientations. At shallow crustal depths, fast orientations in the Eastern Alps are S/N to SSW/NNE, roughly normal to the Alps. This effect is most likely due to the formation of cracks aligned with the present-day stress-field. At greater depths, fast orientations rotate towards NE, almost parallel to the major fault systems that accommodated the lateral extrusion of blocks in the Miocene. This is coherent with the alignment of crystal grains during crustal deformation occurring along the fault systems and the lateral extrusion of the central part of the Eastern Alps.
The synthesis and the characterization of mono- and dinuclear middle transition metal derivatives of 1,10-phenanthroline-5,6-dione,
1, are presented. DFT calculations on CrCl
2(L)(THF)
2 with L
=
O,
...O′-C
12H
6N
2O
2 or
O,
O′-C
14H
8O
2 allowed a direct comparison of the coordination properties of 9,10-phenanthrenequinone and 1,10-phenanthroline-5,6-dione to be made. Dinuclear compounds are reported and the electronic properties of the different complexes are investigated by magnetic moment measurements and EPR spectroscopy.
The synthesis and the characterization of several mono- and dinuclear middle transition metal derivatives of 1,10-phenanthroline-5,6-dione,
1, are presented. The reaction of
1 with CrCl
2(THF)
2 gives CrCl
2(
O,
O′-C
12H
6N
2O
2)(THF)
2,
2, while the halides of iron(II), cobalt(II) and nickel(II) afford adducts of general formula MX
2(
N,
N′-C
12H
6N
2O
2), M
=
Fe,
4, Co,
5, X
=
Cl; M
=
Ni,
6, X
=
Br. DFT calculations on CrCl
2(L)(THF)
2 with L
=
O,
O′-C
12H
6N
2O
2 or
O,
O′-C
14H
8O
2 allowed a direct comparison of the coordination properties of 9,10-phenanthrenequinone and 1,10-phenanthroline-5,6-dione to be made. Dinuclear compounds of general formula CrCl
2(THF)
2(
O,
O′-C
12H
6N
2O
2-
N,
N′)MX
n
L
m
, M
=
Zr,
7, X
=
Cl,
n
=
4,
m
=
0; M
=
Cr,
8, X
=
Cl,
n
=
2, L
=
THF,
m
=
2; M
=
Fe,
9, Co,
10, X
=
Cl,
n
=
2,
m
=
0; M
=
Ni,
11, X
=
Br,
n
=
2,
m
=
0, are prepared from
2 and the corresponding metal halide, while VCp
2(
O,
O′-C
12H
6N
2O
2-
N,
N′)FeCl
2,
12, is synthesized by reacting
4 with VCp
2. The electronic properties of the different complexes are investigated by magnetic moment measurements and EPR spectroscopy.
Laser interferometry enables to remotely measure microscopical length changes of deployed telecommunication cables originating from earthquakes. Long range and compatibility with data traffic make it ...unique to the exploration of remote regions, as well as highly-populated areas where optical networks are pervasive, and its large-scale implementation is attractive for both Earth scientists and telecom operators. However, validation and modeling of its response and sensitivity are still at an early stage and suffer from lack of statistically-significant event catalogs and limited availability of co-located seismometers. We implemented laser interferometry on a land-based telecommunication cable and analyzed 1.5 years of continuous acquisition, with successful detections of events in a broad range of magnitudes, including very weak ones. By comparing fiber and seismometer recordings we determined relations between a cable's detection probability and the magnitude and distance of events, and showed that spectral analysis of recorded data allows considerations on the earthquake dynamics. Our results reveal that quantitative analysis is possible for this sensing technique and support the interpretation of data from the growing amount of interferometric deployments. We anticipate the high integration and scalability of laser interferometry into existing telecommunication grids to be useful for the daily seismicity monitoring, in perspective exploitable for civilian protection use.
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