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1

Subdiffusion of volcanic earthquakes

Abe S., Suzuki N.

Acta Geophysica

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2017

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Vol. 65, no. 3

481--489

EN

A comparative study is performed on volcanic seismicities at Icelandic volcano, Eyjafjallajökull, and Mt. Etna in Sicily from the viewpoint of complex systems science, and the discovery of remarkable similarities between them is reported. In these seismicities as point processes, the jump probability distributions of earthquakes (i.e., distributions of the distance between the hypocenters of two successive events) are found to obey the exponential law, whereas the waiting-time distributions (i.e., distributions of inter-occurrence time of two successive events) follow the power law. A careful analysis is made about the finite size effects on the waiting-time distributions, and the previously reported results for Mt. Etna (Abe and Suzuki 2015) are reinterpreted accordingly. It is shown that the growth of the seismic region in time is subdiffusive at both volcanoes. The aging phenomenon is commonly observed in the “event-time-averaged” mean-squared displacements of the hypocenters. A comment is also made on (non-)Markovianity of the processes.

2

Development of simple analytical methods of polychlorinated biphenyls in human serum by gas chromatography negative ion chemical ionization quadrupole mass spectrometry

Eguchi A., Enomoto T., Suzuki N., Okuno M., Mori C.

Acta Chromatographica

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2017

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Vol. 29, no. 4

503--506

EN

In this study, we developed a highly sensitive, robust method for determining 12 congeners of two to ten chlorinated polychlorinated biphenyls (PCBs) in serum samples using gas chromatography (GC)–mass spectrometry (MS) operating in selected ion monitoring mode (SIM: m/z 35) with negative ion chemical ionization (NICI), and the results were compared with those from GC coupled with high-resolution MS (HRMS) with electron impact (EI). The recovery rates of the surrogate PCB congeners were 97.2%–112% (coefficient of variation: 5.3%–8.5%), and the method detection limits for PCBs in each matrix obtained by GC–NICI–quadrupole mass spectrometry (qMS) were 1.9–20 pg g−1 wet wt. The analytical values of the target compounds in the samples analyzed by GC–NICI–qMS and GC–EI–HRMS were comparable (Passing–Bablok regression: R = 0.888–0.967), and the analytical values obtained via GC–NICI–qMS were almost comparable with those of the certified serum samples from National Institute of Standards and Technology (NIST: SRM1957), indicating that GC–NICI–qMS is suitable for the analysis of tetra- to hepta-chlorinated PCBs in serum samples.

3

Aftershocks in modern perspectives: Complex earthquake network, aging, and non-Markovianity

Abe S., Suzuki N.

Acta Geophysica

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2012

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Vol. 60, no. 3

547-561

EN

The phenomenon of aftershocks is studied in view of science of complexity. In particular, three different concepts are examined: (i) the complex-network representation of seismicity, (ii) the event-event correlations, and (iii) the effects of long-range memory. Regarding (i), it is shown that the clustering coefficient of the complex earthquake network exhibits a peculiar behavior at and after main shocks. Regarding (ii), it is found that aftershocks experience aging, and the associated scaling holds. And regarding (iii), the scaling relation to be satisfied by a class of singular Markovian processes is violated, implying the existence of the longrange memory in processes of aftershocks.