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Fault zone thickness is an important parameter for many seismological models. We present three new fault thickness datasets from different tectonic settings and host rock types. Individual fault zone components (i.e., principal slip zones, fault core, damage zone) display distinct displacement-thickness scaling relationships. Fault component thickness is dependent on the type of deformation elements (e.g., open fractures, gouge, breccia) that accommodate strain, the host lithology, and the geometry of pre-existing structures. A compilation of published fault displacement-thickness data shows a positive trend over seven orders of magnitude, but with three orders of magnitude scatter at a single displacement value. Rather than applying a single power-law scaling relationship to all fault thickness data, it is more appropriate and useful to seek separate scaling relationships for each fault zone component and to understand the controls on such scaling.

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Protection of human life and property from flooding is a strategic priority in the UK. We examine how to encourage home owners to protect themselves and their residences. A model of factors that influence the decision to buy flood protection devices is tested using survey data from 2,109 home owners. The results showed that the majority of respondents have not purchased domestic flood protection (N=1,732; 82.1%). Purchase of flood protection devices was influenced by age; perceived seriousness; and beliefs about, and trust in, the role of regulators in managing flooding. In younger respondents, the perceived seriousness of the dangers of flooding acted as precursors and barriers to action depending on individual sense of responsibility and agency. The second part of the study examined responsiveness to information. Information about flooding alone was insufficient to promote behavioural change, particularly among people who have not experienced a flood or who believe that they are not in a flood zone. Implications for understanding flood protection, managing agency issues, and flood communication campaigns are discussed.

S U M M A R YWe present the spatio-temporal evolution of seismicity recorded by eight three-component digital seismographs in operation continuously during a 3 yr period (1994 August to 1997 at Açu reservoir, NE Brazil. The Açu dam is a 34 m high earth-filled dam constructed in 1983 May on an area of Precambrian shield. Based on seismic monitoring between 1987 and 1989 using single-component analogue seismographs, previous workers concluded that the seismic activity was a case of reservoir-induced seismicity (RIS) associated with diffusion of pore fluid pressure beneath the reservoir. The digital data presented here reveal the seismic activity in remarkable detail with vertical and horizontal location errors ≈0.1 km. A total of 286 events were recorded by three or more stations and all occurred at a depth of <5 km. Using these data we demonstrate that the majority of the earthquake activity is clustered within several well-defined zones and that individual zones are active over discrete periods of time. Over the entire period of seismic monitoring between 1987 and 1997 there is no simple correlation between reservoir level and number of seismic events. Lateral migration of the locus of seismic activity in an unpredictable fashion is shown to be partly responsible for the poor correlation, as event detection is not uniform through time. We also show that the time delay between maximum water level and a subsequent increase in seismic activity varies systematically; longer time delays correspond to activation of an earthquake cluster with a greater average hypocentral depth. However, within any one cluster there is no correlation between time delay and depth. The 3-D distribution of seismic activity through time may only be explained in terms of triggering by the diffusion of pore fluid pressure if the rock properties (e.g. permeability, strength) are heterogeneous.