Present-day kinematics of Eastern African Rift tectonic plates using continuous and episodic GPS data
Abstract
This paper focuses on the tectonic setup of the East African Rift, a complex system that extends from the Afar region where the triple junction between Somalia, Nubia and Arabia plates is located to the South West Indian Ridge where the Nubia and Antarctica meets with a third tectonic unit - possibly the so-called Lwandle block which is considered by several authors as an independent unit of the Somalia plate. We present a consistent velocity field derived from continuous and episodic GPS observations. The analyzed data were obtained from several permanent stations distributed all over the African continent and surrounding regions and significantly extended with episodic data acquired in the framework of the KINEMA (KINEmatics of Margins of Africa) and other projects. Some of the available episodic observations had a significant low quality due to short observation periods and/or lack of proper re-centring during the different occupations since many of the observations were not acquired for scientific purposes. However, they have been evaluated and they are considerably contributing to densify our velocity field. The network of permanent stations also includes some stations recently installed in the framework of KINEMA. Most of them still have short data spans to properly access his linear motion. Nevertheless, they already provide valuable indications about the present-day kinematics of the blocks where they are located. The estimated angular velocities are computed with respect to ITRF2005. On the near-field, two regions are discussed in more detail: the interactions between the Nubia and the tectonic blocks of Rovuma and Lwandle in the Mozambican region (where the episodic observations are located), and the kinematics of Victoria plate in the Kenyan region. With respect to the triplet Nubia-Rovuma-Lwandle, the small number of data points associated with to the low magnitude of the relative angular velocity between these different blocks has prevented to quantify their relative motion. In this case, we are using mainly campaign observations, acquired since 1995, to reduce such uncertainties. The plate boundaries of the Victoria plate with respect to Nubia and Somalia plates are clearly defined by the two arms of the East African Rift. We attempt to quantify between this tectonic unit and the Rovuma block by differencing their estimated angular velocities with respect to ITRF2005.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2009
- Bibcode:
- 2009AGUFM.G33B0634F
- Keywords:
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- 1209 GEODESY AND GRAVITY / Tectonic deformation