Subdiffusion of volcanic earthquakes

TL;DR

This study compares seismic activities at Iceland's Eyjafjallajökull and Mt. Etna, revealing subdiffusive behavior and aging phenomena in earthquake hypocenter movements, with implications for understanding volcanic seismicity as complex systems.

Contribution

It demonstrates that volcanic earthquakes exhibit subdiffusive dynamics and aging effects, providing new insights into their complex temporal and spatial patterns.

Findings

Seismic jump distances follow exponential distribution.

Waiting times between earthquakes follow power-law distribution.

Seismic regions grow subdiffusively over time.

Abstract

A comparative study is performed on volcanic seismicities at Icelandic volcano, Eyjafjallaj\"okull, 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.