Temporal analysis of acoustic emission from a plunged granular bed

Abstract

The statistical property of acoustic emission (AE) events from a plunged granular bed is analyzed by means of actual time and natural time analyses. These temporal analysis methods allow us to investigate the details of AE events that follow a power-law distribution. In the actual time analysis, the calm time distribution and the decay of the event-occurrence density after the largest event (i.e., Omori-Utsu law) are measured. Although the former always shows a power-law form, the latter does not always obey a power law. Markovianity of the event-occurrence process is also verified using a scaling law by assuming that both of them exhibit power laws. We find that the effective shear strain rate is a key parameter to classify the emergence rate of power-law nature and Markovianity in the granular AE events. For the natural time analysis, the existence of self organized critical (SOC) states is revealed by calculating the variance of natural time χ k , where kth natural time of N events is defined as χ k = k/N . In addition, the energy difference distribution can be fitted by a q-Gaussian form, which is also consistent with the criticality of the system.

Estimating the Epicenter of a Future Strong Earthquake in Southern California, Mexico, and Central America by Means of Natural Time Analysis and Earthquake Nowcasting

“…Natural time was introduced [ 5 ] in 2001 as a general method to analyze time-series resulting from complex systems [ 7 ]. It has been applied to a variety of fields, such as condensed matter physics [ 22 , 23 , 24 ], geophysics [ 6 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 ], civil engineering [ 35 , 36 , 37 , 38 ], climatology [ 39 , 40 , 41 , 42 ], and biomedical engineering [ 43 , 44 ]. Within the concept of NTA, it has been shown that the variance of natural time may be considered as an order parameter for seismicity [ 3 , 45 , 46 , 47 , 48 , 49 ] as well as in acoustic emission before fracture [ 28 , 50 ] or in other self-organized critical phenomena such as ricepiles [ 51 ] and avalanches in the Olami–Feder–Christensen [ 52 ] earthquake model [ 53 ] or in the Burridge–Knopoff [ 54 ] train model [ 55 ].…”

Subdiffusion of volcanic earthquakes

“…As additional information, we also point out that Eq. ( 6) has also been discussed in other contexts including laser cooling of atoms (Bardou et al 2002) and acoustic emissions from plunged granular materials to examine (non-)Markovianity (Tsuji and Katsuragi 2015).…”

Detecting Criticality by Exploring the Acoustic Activity in Terms of the “Natural-Time” Concept

“…In this context, the Natural Time concept became gradually a valuable alternative tool in the tedious effort of the scientific community to develop theories for the prediction of upcoming catastrophic events. Soon after the concept was introduced it was adopted for data analysis in an amazingly wide range of scientific disciplines, from seismology [26][27][28][29][30], to medicine [31,32], condensed matter physics [33] and mechanics of materials [34][35][36][37][38][39][40].…”