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Seismometer Detection of Dust Devil Vortices by Ground Tilt

Lorenz, Ralph D. and Kedar, Sharon and Murdoch, Naomi and Lognonné, Philippe and Kawamura, Taichi and Mimoun, David and Banerdt, William Bruce Seismometer Detection of Dust Devil Vortices by Ground Tilt. (2015) Bulletin of the Seismological Society of America, vol. 105 (n° 6). pp. 3015-3023. ISSN 0037-1106

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Official URL: http://dx.doi.org/10.1785/0120150133

Abstract

We report seismic signals on a desert playa caused by convective vortices and dust devils. The long-period (10–100 s) signatures, with tilts of ∼10−7 radians, are correlated with the presence of vortices, detected with nearby sensors as sharp temporary pressure drops (0.2–1 mbar) and solar obscuration by dust. We show that the shape and amplitude of the signals, manifesting primarily as horizontal accelerations, can be modeled approximately with a simple quasi-static point-load model of the negative pressure field associated with the vortices acting on the ground as an elastic halfspace. We suggest the load imposed by a dust devil of diameter D and core pressure ΔPo is ∼(π/2)ΔPoD^2, or for a typical terrestrial dust devil of 5m diameter and 2mbar, about the weight of a small car. The tilt depends on the inverse square of distance and on the elastic properties of the ground, and the large signals we observe are in part due to the relatively soft playa sediment and the shallow installation of the instrument. Ground tilt may be a particularly sensitive means of detecting dust devils. The simple point-load model fails for large dust devils at short ranges, but more elaborate models incorporating the work of Sorrells (1971) may explain some of the more complex features in such cases, taking the vortex winds and ground velocity into account. We discuss some implications for the InSight mission to Mars.

Item Type:Article
Audience (journal):International peer-reviewed journal
Uncontrolled Keywords:
Institution:Other partners > Institut de Physique du Globe de Paris - IPGP (FRANCE)
Université de Toulouse > Institut Supérieur de l'Aéronautique et de l'Espace - ISAE-SUPAERO (FRANCE)
Other partners > Université de Paris Diderot - Paris 7 (FRANCE)
Other partners > California Institute of Technology - Caltech (USA)
Other partners > Johns Hopkins University - JHU (USA)
Laboratory name:
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Deposited By: Naomi Murdoch
Deposited On:20 Dec 2016 15:17

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