Geological Society of America

T117 Volcano-Tectonic Evolution of the East African Rift System

Monday, 23 October 2017
8:00 AM - 12:00 PM
Yakima 1

SENTINEL-1 INSAR OBSERVATIONS OF GROUND DEFORMATION IN THE EARLY-STAGE NORTHERN NYASA RIFT

Paper number: T117-6
Program: Technical Sessions
Time: 9:15 AM – 9:30 AM

Authors

S.T. Henderson Presenting Author
University of Washington, Seattle, WA
M.E. Pritchard
Cornell University, Ithaca, NY
W. Zheng
Cornell University, Ithaca, NY
S.J. Oliva
Tulane University, New Orleans, LA
C.J. Ebinger
Tulane University, New Orleans, LA
J. Elliott
Purdue University, West Lafayette, IN
E. Saria
Ardhi University, Dar es Salaam
D. Ntambila
Ardhi University, Dar es Salaam
P.R.N. Chindandali
Geological Survey of Malawi, Zomba

Abstract

The SEGMeNT (Study of Extension and maGmatism in Malawi aNd Tanzania) multidisciplinary research project is focused on understanding the dynamics of early-stage rifting. An important objective of the project is to quantify surface deformation associated with active tectonic processes: Including strain rates from active extension, co-seismic displacements due to crustal faulting, and uplift due to magmatic intrusions. Since 2012, the project has deployed several geophysical monitoring networks, including GPS and seismic stations spanning a 500km region. Geodetic ground stations have been augmented by regular ESA Sentinel SAR imagery acquisitions since 10/2014, but InSAR measurements of ground motion are encumbered by atmospheric noise. We have processed hundreds of interferograms through 06/2017 in order to mitigate atmospheric signals and provide a synoptic view of average surface motions in the region. InSAR observations have proven especially useful in constraining fault models of shallow crustal earthquakes. For example, global moment tensor catalog epicentral locations for a Mw5.1 earthquake occurring on 12/31/2014 near Karonga, Malawi differ by over 20km. Geodetic models of normal faulting, based on a moment tensor solution using data from the SEGMeNT seismic array, are consistent with 3 cm of subsidence located 10km from the nearest global catalog epicenter. We also report on the InSAR observations within 20 km of each SEGMeNT GPS station and compare the results with GPS time series. In addition, we will discuss the lack of observed surface displacements of magmatic origin at the Holocene Rungwe Volcanic complex.

Geological Society of America Abstracts with Programs. Vol. 49, No. 6

doi: 10.1130/abs/2017AM-306773

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