Abstract. In this article we summarize the availability of earthquake source mechanisms in Bulletin International Seismological Centre (ISC). The bulletin its current status contains ∼81 000 seismic events with only one associated mechanism solution and ∼25 at least two mechanisms. main sources ISC are reported solutions provided by data contributors ISC-computed focal based on first motion polarities. Given importance using pre-determined fault plane different types studies, here briefly...

Abstract The use of fiber infrastructures for environmental sensing is attracting global interest, as optical fibers emerge low cost and easily accessible platforms exhibiting a large terrestrial deployment. Moreover, networks offer the unique advantage providing observations submarine areas, where sparse existence permanent seismic instrumentation due to difficulties in deployment limits availability high-resolution subsea information on natural hazards both time space. techniques that...

SUMMARY We present a theory and conceptual examples for fibre-optic deformation sensing based on phase changes of transmitted light. As first result, we establish an exact relation between observable the tensor along fibre. This is nonlinear includes effects related to both local in fibre length deformation-induced refractive index. In cases where norm much smaller than 1, useful first-order can be derived. It connects integral over in-line strain times When spatial variations index are...

We present spectra concentrating on the lowest-frequency normal modes of Earth obtained from records invar-wire strainmeters and STS-1 broad-band seismometers located in Black Forest Observatory, Germany after disastrous earthquakes off NW coast Sumatra 2004 near Tohoku, Japan 2011. compare to ones synthetic seismograms computed using a mode summation technique for an anelastic, elliptical, rotating, spherically symmetric model. The synthetics include strain–strain-coupling effects by...

On 30 October 2020, the island of Samos (Greece) and region Izmir (Türkiye) were hit by a powerful earthquake followed tsunami that spread across Aegean Sea. The magnitude M7.0 caused severe damage more than 100 deaths in both countries, including one death Türkiye due to tsunami. This disaster was yet another reminder Mediterranean region's vulnerability seismic hazards. It highlighted critical significance prevention preparedness mitigating impacts natural...

Distributed Acoustic Sensing (DAS) has become a popular method of observing seismic wavefields: backscattered pulses light reveal strains or strain-rates at any location along fiber-optic cable. In contrast, few newer systems transmit through cable and collect integrated phase delays over the entire cable, such as Microwave Frequency Fiber Interferometer (MFFI). These can be deployed significantly longer distances, may used in conjunction with live telecommunications, cheaper. However, they...

The Bulletin of the International Seismological Centre (ISC) contains information on earthquake mechanisms collected from many different sources including national and global agencies, resulting in a satisfactory coverage over wide magnitude range (M ∼2–9). Nevertheless, there are still vast number earthquakes with no reported source especially for magnitudes up to 5. This study investigates possibility calculating focal routine systematic way based P-wave first motion polarities. Any...

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Abstract We study the strong 12 October 2021, $$M_W$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mi>M</mml:mi> <mml:mi>W</mml:mi> </mml:msub> </mml:math> =6.4, offshore Zakros, Crete earthquake, and its seismotectonic implications. obtain a robust location (azimuthal gap equal to 17 $$^{\circ }$$ <mml:msup> <mml:mrow /> <mml:mo>∘</mml:mo> </mml:msup> ) for mainshock by combining all freely available local, regional teleseismic phase arrivals (direct depth...

We experimentally demonstrate a microwave frequency dissemination system operating as sensitive interferometric sensor of seismic waves on commercially deployed fiber networks in Attika, Greece. Efficient detection from distant epicenters (&gt;400km) is presented

SUMMARY Fibre-optic sensing based on transmission offer an alternative to scattering-based distributed acoustic (DAS). The ability interrogate fibres that are thousands of kilometres long opens opportunities for studies remote regions, including ocean basins. However, by averaging deformation along the fibre, systems produce integrated instead measurements. They defy traditional interpretations in terms simple seismic phases, thereby inherently requiring a full-waveform approach. For this,...

Abstract The use of fiber infrastructures for environmental sensing is attracting global interest, as optical fibers emerge low cost and easily accessible platforms exhibiting a large terrestrial deployment. Moreover, networks offer the unique advantage providing observations submarine areas, where sparse existence permanent seismic instrumentation due to difficulties in deployment limits availability high-resolution subsea information on natural hazards both time space. techniques that...

This manuscript is concerned with phase changes of signals transmitted through deforming optical fibres. As a first result, it establishes an exact relation between observable and the deformation tensor along fibre. non-linear, includes effects related to both local in fibre length deformation-induced speed light or refractive index. In seismic applications, where norm earthquake-induced orders magnitude smaller than 1, useful first-order can be derived. It simply connects integral over...

Abstract We study the major M w 7.0, 30 October 2020, Samos earthquake and its aftershocks, by calculating improved locations using differential travel times waveform cross-correlations.We image rupture of mainshock local strong motion data, we examine Coulomb stress evolution prior to mainshock, as well coseismic changes. Lastly, estimate produced shaking all available information from data testimonies. Earthquake relocations reveal activation E-W oriented, Kaystrios fault, in North basin...

SUMMARY Instrumental earthquake monitoring in Greece started 1899–1906 with the first five seismic stations of National Observatory Athens, Institute Geodynamics (NOA). Subsequent upgrades and expansions led to today’s Unified Seismic Network, which includes almost all permanent provides waveform parametric data. We examine detection capabilities Greek networks using phase, location magnitude data from International Seismological Centre (ISC) various Institutes. apply two methods measure...

In St. Martin, the Oligocene granitoids comprise granodiorites, leucotonalites, melatonalites and Qz-monzodiorites. Tonalites are low-K, whereas granodiorites Qz-monzodiorites related with calc-alkaline suites. Mineralogical, geochemical Sr-Nd isotopic data denote that most rocks I-type calc-alkaline, except for seemingly resemble peraluminous S-type granitoids. The display lowest Al2O3/TiO2 highest CaO/Na2O ratios, pointing to high temperature conditions. Various geothermometry...

We experimentally demonstrate a microwave frequency dissemination system operating as sensitive interferometric sensor of seismic waves on commercially deployed fiber networks in Attika, Greece. Efficient detection from distant epicenters (>400km)

Abstract. In this article we summarize the availability of earthquake source mechanisms in Bulletin International Seismological Centre (ISC). The bulletin its current status contains ∼ 81,000 seismic events with only one associated mechanism solution, and 22,000 at least two mechanisms. main sources ISC are reported solutions provided by data contributors, computed focal based on first motion polarities. Given importance using pre-determined fault plane different types studies, here focus...