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Title: E.M. induction studies in a region of active crustal dislocation
Author: Russell, Martin
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 1988
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During a six month period in 1984 synchronous Electromagnetic data were recorded from a 5 site MT array located near the town of Izmit, western Turkey. The array was located over an active earthquake swarm which forms part of the active North Anatolian Fault (NAF). The recordings covered a band width of 10 to 10000 seconds. Both Single Site (SS) and Remote Reference (RR) processing techniques were employed to produce impedance tensors for MT, Vertical and Horizontal fields. Results for consecutive 5 day groups provide maximum resolution for the time dependency study, while 30 day groups provide high resolution sounding curves that are used in the construction of a geoelectric model for the area. Interpretation of the MT sounding curves indicates that induction is controlled by a thin sheet mechanism which gives rise to static shifts in all the MT curves. Regional geoelectric strikes correlate well with the azimuths of regional stress (ESE-WNW). A 1-dimensional (1-D) geoelectric model was derived based on the MT phase curves of sites 222 and 333. The first layer, 10 to 14 km thick with a resistivity of 60 to 100 ohm.m., correlates well with the brittle fracture seismogenic zone of the upper crust in this region. This zone overlies a more resistive layer of 800 to 1000 ohm.m. Time dependency results highlight the need to adopt robust methods for data collection and processing. Within the limits of data resolution and because of low level seismic activity, no precursory changes in the electromagnetic transfer functions were observed. Horizontal field transfer functions provided the most consistent and accurately resolved results.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available