TY  - JOUR
A1  - Maghsoudi, Samira
A1  - Hainzl, Sebastian
A1  - Cesca, Simone
A1  - Dahm, Torsten
A1  - Kaiser, Diethelm
T1  - Identification and characterization of growing large-scale en-echelon fractures in a salt mine
T2  - Geophysical journal international
N2  - The spatiotemporal seismicity of acoustic emission (AE) events recorded in the Morsleben salt mine is investigated. Almost a year after backfilling of the cavities from 2003, microevents are distributed with distinctive stripe shapes above cavities at different depth levels. The physical forces driving the creation of these stripes are still unknown. This study aims to find the active stripes and track fracture developments over time by combining two different temporal and spatial clustering techniques into a single methodological approach. Anomalous seismicity parameters values like sharp b-value changes for two active stripes are good indicators to explain possible stress accumulation at the stripe tips. We identify the formation of two new seismicity stripes and show that the AE activities in active clusters are migrated mostly unidirectional to eastward and upward. This indicates that the growth of underlying macrofractures is controlled by the gradient of extensional stress. Studying size distribution characteristic in terms of frequency-magnitude distribution and b-value in active phase and phase with constant seismicity rate show that deviations from the Gutenberg-Richter power law can be explained by the inclusion of different activity phases: (1) the inactive period before the formation of macrofractures, which is characterized by a deficit of larger events (higher b-values) and (2) the period of fracture growth characterized by the occurrence of larger events (smaller b-values).
KW  - Earthquake source observations
KW  - Statistical seismology
Y1  - 2014
UR  - https://publishup.uni-potsdam.de/frontdoor/index/index/docId/38116
SN  - 0956-540X
SN  - 1365-246X
VL  - 196
IS  - 2
SP  - 1092
EP  - 1105
PB  - Oxford Univ. Press
CY  - Oxford
ER  -