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|Spuren des Plumes und Strukturen des oberen Mantels unter Hawaii abgeleitet aus konvertierten Wellen|
|Main title||Spuren des Plumes und Strukturen des oberen Mantels unter Hawaii abgeleitet aus konvertierten Wellen|
|Title variations||Traces of the plume and structures of the upper mantle beneath Hawaii derived from converted phases|
Place of birth: Zeven, Deutschland
|1. Referee||Prof. Dr. Rainer Kind|
|Further Referee(s)||Priv. Doz. Dr. Günter Asch|
|Keywords||hotspot, plume, mantle discontinuities, Hawaii, receiver functions|
|Classification (DDC)||550 Earth sciences|
|Summary||Hawaii is one of the best-known examples of hotspot volcanism in the world. The insulated position in the central Pacific keeps away additional tectonic effects. Hence, in the context of mantle plumes Hawaii is a site of special interest.
Until now neither the depth of the plume source nor the exact position of its conduit in the mantle are well-known. Answers to these questions may also bring new cognition linked to the dynamical processes of the mantle such as convection.
Within this work the receiver function technique has been applied to image seimic velocity structures down to the uppermost part of the lower mantle beneath Hawaii. Data from eleven temporary broadband seismic stations located on the four biggest Hawaiian islands have been investigated. Supplementary data have been available from permanent broadband stations. A couple of observations have been made in different depths.
Moho depths between 12 - 17 km have been derived. Underneath the younger part of the island chain from the Big Island to Oahu an additional converted phase beeing generated within the crust. To the younger part it is occuring systematically earlier in the seismic section.
The lithosphere-asthenosphere boundary was clearly observed in the area under investigation. The thickness of the lithosphere is decreasing to the older part of the island chain. Within the asthenosphere a local low velocity zone has been verified underneath the Big Island. The discontinuities of the mantle transition zone in 410 km and 660 km depth have also been identified. In some parts also converted phases generated at 520 km and also greater depths have been found.
According to arrival times of the P410s and P660s phases the area could have been devided into three regions: The southeast does not show any influences of a mantle plume at all, while in the northwestern part reduced S-wave velocities in the uppermost mantle are found. Southwest of the Big Island, finally, thinning of the mantle transition zone indicates the position of the plume conduit in this depths with a core radius of about 120 km.
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|FU Department||Department of Earth Sciences|
|Year of publication||2004|
|Document type||Doctoral thesis|
|Date of defense||2003-12-15|
|Created at||2004-07-14 : 12:00:00|
|Last changed||2010-02-19 : 10:06:13|
|Old Darwin URL||http://www.diss.fu-berlin.de/2004/172/|