Details of Award
NERC Reference : NE/C00132X/1
The Influence of the Viscoelastic Relaxation on the Effective Duration of Coulomb Stress Perturbations
Grant Award
- Principal Investigator:
- Dr S Nalbant, University of Ulster, Sch of Environmental Sciences
- Co-Investigator:
- Professor S Steacy, University of Adelaide, Unlisted
- Co-Investigator:
- Professor J McCloskey, University of Edinburgh, Sch of Geosciences
- Grant held at:
- University of Ulster, Sch of Environmental Sciences
- Science Area:
- Earth
- Overall Classification:
- Earth
- ENRIs:
- Environmental Risks and Hazards
- Science Topics:
- Tectonic Processes
- Geohazards
- Abstract:
- Summary It has long been understood that earthquakes trigger future earthquakes, in other words that an earthquake is more likely to occur when a previous earthquake has already occurred. One common type of related earthquakes is a mainshock-aftershock sequence in which a moderate to large earthquake (say greater than magnitude 5) is followed by a sequence of smaller events, closely related to it in space and time. Over the past 10 years, it has been learned that the spatial distribution of aftershocks is related to the stress changes from the mainshock, in other words that aftershocks cluster in areas where the stress has increased and generally don't occur in regions where it has decreased. More recently, research has shown that such stress changes can affect the timing and location of subsequent mainshocks, with large apparently triggered events occurring on faults where the stress has been increased due to previous earthquakes. The timing, or duration, of such large event interaction is not well understood. Studies along simple fault zones in Turkey have shown that these effects can last for greater than 50 years while research on smaller events in a more structurally complex area in California found that stress interaction is only important for a year or two. There are two main mechanisms that can affect these static (or time independent) stress changes. The first is additional stress changes due to subsequent earthquakes, the second is viscoelastic stress transfer. The Earth's crust is made up of two layers, an upper brittle layer that deforms by cracking or breaking, and a lower viscoelastic layer that deforms by flow. When an earthquake occurs in the upper part of the crust, the lower part must 'catch up'; this lower-crustal flow redistributes stress and hence modifies the static stress changes due to the mainshock. The aim of this study is to understand the timescale over which static stress changes are important and to test the hypothesis that stress calculations that include viscoelastic effects will better delineate regions likely to experience further earthquakes than purely static stress calculations. The results will be useful both for seismic hazard and in understanding the physics of earthquakes.
- NERC Reference:
- NE/C00132X/1
- Grant Stage:
- Completed
- Scheme:
- Small Grants Pre FEC
- Grant Status:
- Closed
- Programme:
- Small Grants
This grant award has a total value of £26,924
FDAB - Financial Details (Award breakdown by headings)
| Total - T&S | Total - Staff | Total - Other Costs | Total - Indirect Costs |
|---|---|---|---|
| £4,158 | £14,526 | £1,560 | £6,682 |
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