Abstract
In this study, the characterization of the depth of the Mohorovicic discontinuity under the crust of Funafuti island was determined by analyzing the 3 component seismograms from 54 different earthquake events recorded by the station between 2008 and 2012. These seismograms were from teleseismic earthquakes whose epicenter lay at distances greater than 3000 km from the station. The seismograms were iteratively deconvolved in the time domain to remove the unwanted noise and then stacked to obtain better receiver functions. For analysis of the receiver functions, it was assumed that the range in which the Vp/Vs ratio would lie for the given region would be between 1.60 - 1.85 and the depth of the discontinuity was assumed to lie between 5 - 20 km. Analysis of the receiver functions showed that the Mohorovicic discontinuity was at a depth of 11 km and the Vp/Vs ratio was 1.75 for the region.
Highlights
Funafuti is an atoll which is the capital of the island nation Tuvalu
In addition the seismograms are visually verified to ensure that the P arrivals are impulsive and only are they sent for further processing
The basis of the iterative time domain deconvolution method [10] is least-squares minimization of the difference between the observed horizontal seismogram and a predicted seismogram. This is obtained by the convolution of an iteratively updated spike train and the vertical component of the seismogram
Summary
Funafuti is an atoll which is the capital of the island nation Tuvalu. The nation is believed to be first inhabited by migrated Polynesians. These separate islands were together earlier known as Ellice Islands and were ruled by the British Empire. Receiver function analysis is a very easy and an economical method [1] used to map the subsurface structures. It becomes very expensive if conventional seismic imaging techniques using explosives and geophones are used or if other techniques like wireline logging and downhole logging are used. Receiver function analysis has been used many times in the past [2,3] to find out the depth of the Mohorovičić discontinuity which is the boundary between the lower crust and the upper mantle
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