HR: 1330h
AN: V52B-0424    [PDF]
TI: A statistical model for the timing of earthquakes and volcanic eruptions influenced by periodic processes
AU: * Jupp, T
EM: tim@bpi.cam.ac.uk
AF: BP Institute for Multiphase Flow, University of Cambridge, Madingley Rise, Madingley Road, Cambridge, CB3 0EZ United Kingdom
AU: Pyle, D
EM: dmp11@esc.cam.ac.uk
AF: Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge, CB2 3EQ United Kingdom
AU: Mason, B
EM: bgm21@hermes.cam.ac.uk
AF: Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge, CB2 3EQ United Kingdom
AU: Dade, B
EM: W.Brian.Dade@dartmouth.edu
AF: Department of Earth Sciences, Dartmouth College, Hanover, NH NH 03755 United States
AB: Evidence of non-uniformity in the rate of seismicity and volcanicity has been sought on a variety of timescales ranging from $12$ hours (tidal) to $10^{3} \ - \ 10^{4}$ years (climatic), but the results are mixed. Here, we propose a simple conceptual model for the influence of periodic processes on the frequency of geophysical `failure events' such as earthquakes and volcanic eruptions. In our model a failure event occurs at a `failure time' $t_{F}=t_{I}+t_{R}$ which is controlled by an `initiation event' at the `initiation time' $t_{I}$ and by the `response time' of the system $t_{R}$. We treat each of the initiation time, the response time and the failure time as random variables. In physical terms, we define the initiation time to be the time at which a `load function' exceeds a `strength function' and we imagine that the `response time' $t_{R}$ corresponds to a physical process such as crack propagation or the movement of magma. Assuming that the magnitude and frequency of the periodic process are known, we calculate the statistical distribution of the initiation times on the assumption that the load and strength functions are otherwise linear in time. This allows the distribution of the failure times to be calculated, if the distribution of the response times is known also. The predictions of this simple theory are compared with some examples of observed periodicity in seismic and volcanic activity at tidal and annual timescales.
DE: 3210 Modeling
DE: 7280 Volcano seismology (8419)
DE: 8400 VOLCANOLOGY
DE: 8414 Eruption mechanisms
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2003 Fall Meeting