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SUMMARY This paper presents a new derivative-free search method for finding models of acceptable data fit in a multidimensional parameter space. It falls into the same class of method as simulated annealing and genetic algorithms, which are commonly used for global optimization problems. The objective here is to find an ensemble of models that… (More)

SUMMARY Monte Carlo direct search methods, such as genetic algorithms, simulated annealing etc., are often used to explore a finite dimensional parameter space. They require the solving of the forward problem many times, that is, making predictions of observables from an earth model. The resulting ensemble of earth models represents all 'information'… (More)

The major cause of sea-level change during ice ages is the exchange of water between ice and ocean and the planet's dynamic response to the changing surface load. Inversion of ∼1,000 observations for the past 35,000 y from localities far from former ice margins has provided new constraints on the fluctuation of ice volume in this interval. Key results are:… (More)

Monte Carlo methods have become important in analysis of nonlinear inverse problems where no analytical expression for the forward relation between data and model parameters is available, and where linearization is unsuccessful. In such cases a direct mathematical treatment is impossible, but the forward relation materializes itself as an algorithm allowing… (More)

[1] Monte Carlo inversion techniques were first used by Earth scientists more than 30 years ago. Since that time they have been applied to a wide range of problems, from the inversion of free oscillation data for whole Earth seismic structure to studies at the meter-scale lengths encountered in exploration seismology. This paper traces the development and… (More)

A discussion of methodologies for nonlinear geophysical inverse problems is presented. Geophysical inverse problems are often posed as optimization problems in a finite-dimensional parameter space. An Earth model is usually described by a set of parameters representing one or more geophysical properties (e.g. the speed with which seismic waves travel… (More)

A recently proposed new class of direct search method is applied to the problem of mapping out the region of data-acceptable models (sets of unknowns) in a finite-dimensional nonlinear inverse problem. A model is defined to be data acceptable if its fit to the observed data is better than some prescribed level. The neighbourhood algorithm (NA) can be used… (More)

Working with a large temporal dataset spanning several decades often represents a challenging task, especially when the record is heterogeneous and incomplete. The use of statistical laws could potentially overcome these problems. Here we apply Benford's Law (also called the "First-Digit Law") to the traveled distances of tropical cyclones since 1842. The… (More)

- Anya Reading, Brian Kennett, Malcolm Sambridge
- 2003

[1] The determination of structure from the inversion of teleseismic receiver functions may be improved by removing the contribution of the free surface. The free surface interaction gives rise to the highest amplitude signal on standard receiver functions and yet this initial pulse tells us little about the receiver structure below the surface layer. We… (More)

Synthetic experiments are used to test the applicability of coda wave interferometry (CWI) as a means for estimating distance between sources of nearby earthquakes. Acoustic waves for 45 sources are propagated through a Gaussian random medium. A pair-wise analysis of resulting waveforms illustrates the applicability of CWI as a tool for estimating source… (More)