Joint inversion of seismic and gravity data beneath the Iberian Peninsula for crustal and upper mantle structure
Abstract
Preliminary 3D Vp and Vs models for the Iberian Peninsula and surrounding areas are presented. These models are derived from the simultaneous inversion of body wave first-arrival times, surface wave dispersion curves, and gravity data, which builds upon the relative sensitivities of each dataset. Body wave travel times constrain Vp and Vs, with sampling dependent on the natural distribution of seismicity. Throughout most of the region, the predominance of crustal earthquakes limit body wave sampling to the crust and uppermost mantle, while seismicity deeper than 100 km beneath the Gibraltar Arc increases resolution locally. Phase- and group-velocity dispersion curves for Rayleigh waves between 4 and 40 sec, derived by ambient noise tomography using data recorded by the IberArray experiment, permanent networks in the region, and other temporary deployments strongly constrain crustal Vs independently of seismicity. Gravity constrains shallow crustal Vp and Vs independently of both seismicity and seismic station distributions, although it cannot constrain changes in velocity structure with depth in areas without seismic sampling. Gravity and velocity are related through empirical relationships between seismic velocity and density, so that both seismic and gravity datasets can be used in the same inversion. Preliminary results of joint surface wave and gravity inversions show the main structural elements of the region, including most elevated velocities within the Mediterranean upper mantle, moderately high velocities associated with the Iberian Massif, and low velocities beneath the Pyrenees. Very prominent low-velocity anomalies surround the Gibraltar Arc, where subduction occurred during the Early and Middle Miocene.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2016
- Bibcode:
- 2016AGUFM.S33F..03S
- Keywords:
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- 3260 Inverse theory;
- MATHEMATICAL GEOPHYSICSDE: 3275 Uncertainty quantification;
- MATHEMATICAL GEOPHYSICSDE: 7270 Tomography;
- SEISMOLOGYDE: 7290 Computational seismology;
- SEISMOLOGY