Spatio-temporal characteristics of the geomagnetic field over the Lombok Island, the Lesser Sunda Islands region : new geological, tectonic, and seismo-electromagnetic insights along the Sunda-Banda Arcs transition [Elektronische Ressource] / Teti Zubaidah. Deutsches GeoForschungsZentrum GFZ

Zubaidah

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• Publié par: universitat_potsdam
• Publié le: 01 janvier 2010
• Nombre de lectures: 23
• Poids de l'ouvrage: 7 Mo

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Teti Zubaidah
Spatio-temporal characteristics
of the geomagnetic field over
the Lombok Island, the Lesser
Sunda Islands region:
New geological, tectonic, and
seismo-electromagnetic
insights along the Sunda-Banda
Arcs transition
Scientific Technical Report STR10/07
ISSN 1610-0956 www.gfz-potsdam.de
STR10/07
Teti Zubaidah, Spatio-temporal characteristics of the geomagnetic field over the Lombok IslandTeti Zubaidah
Spatio-temporal characteristics
of the geomagnetic field over
the Lombok Island, the Lesser
Sunda Islands region:
New geological, tectonic, and
seismo-electromagnetic
insights along the Sunda-Banda
Arcs transition
Dissertation
zur Erlangung des akademischen Grades
doctor rerum naturalium (Dr. rer. nat.)
in der Wissenschaftsdisziplin Geowissenschaften
eingereicht an der Mathematisch-Naturwissenschaftlichen Fakultät
der Universität Potsdam
März 2010
Impressum
Telegrafenberg
D-14473 Potsdam
Gedruckt in Potsdam
April 2010
Scientific Technical Report STR10/07ISSN 1610-0956
Die vorliegende Arbeit
in der Schriftenreihe
Scientific Technical Report (STR) des GFZ
ist in elektronischer Form erhältlich unter
www.gfz-potsdam.de - Neuestes - Neue
Publikationen des GFZ
Imprint
Telegrafenberg
D-14473 Potsdam
Printed in Potsdam, Germany
November 2008
ISSN 1610-0956
This work is published in the GFZ series
Scientific Technical Report (STR)
and is open accessible available at:
www.gfz-potsdam.de - News - GFZ
Publications
im Fachbereich GeowissenschaftenTeti Zubaidah
Spatio-temporal characteristics
of the geomagnetic field over
the Lombok Island, the Lesser
Sunda Islands region:
New geological, tectonic, and
seismo-electromagnetic
insights along the Sunda-Banda
Arcs transition
Dissertation
zur Erlangung des akademischen Grades
doctor rerum naturalium (Dr. rer. nat.)
in der Wissenschaftsdisziplin Geowissenschaften
eingereicht an der Mathematisch-Naturwissenschaftlichen Fakultät
der Universität Potsdam
März 2010
1. Gutachter: Prof. Dr. Michael Weber
2. Gutachter: Prof. Sri Widiyantoro PhD
3. Gutachter: Prof. Dr. Katsumi Hattori
Mitglieder der Kommission:
Prof. Dr. Frank Krueger
Prof. Dr. Patrick O'Brien
Prof. Dr. Romain Bousquet
Prof. Dr. Mioara Mandea
Prof. Dr. Mohamed HamoudiImpressum
Dr. Makky Sandra Jaya
Betreuerin des GFZ:
Dr. Monika Korte
Telegrafenberg
D-14473 Potsdam
Gedruckt in Potsdam
April 2010
Scientific Technical Report STR10/07ISSN 1610-0956
Die vorliegende Arbeit
in der Schriftenreihe
Scientific Technical Report (STR) des GFZ
ist in elektronischer Form erhältlich unter
www.gfz-potsdam.de - Neuestes - Neue
Publikationen des GFZ
Deutsches GeoForschungsZentrum GFZScientific Technical Report STR 10/07
DOI: 10.2312/GFZ.b103-10079
Imprint
Telegrafenberg
D-14473 Potsdam
Printed in Potsdam, Germany
November 2008
ISSN 1610-0956
This work is published in the GFZ series
Scientific Technical Report (STR)
and is open accessible available at:
www.gfz-potsdam.de - News - GFZ
Publications
im Fachbereich GeowissenschaftenInstitut für Erd- und Umweltwissenschaften



Spatio-temporal characteristics of the geomagnetic field over
the Lombok Island, the Lesser Sunda Islands region:
New geological, tectonic, and seismo-electromagnetic insights
along the Sunda-Banda Arcs transition










Dissertation
zur Erlangung des akademischen Grades
"doctor rerum naturalium"
(Dr. rer. nat.)
in der Wissenschaftsdisziplin " Geowissenschaften"











eingereicht an der
Mathematisch-Naturwissenschaftlichen Fakultät
der Universität Potsdam




von
Teti Zubaidah





Potsdam, den 29. März 2010
Deutsches GeoForschungsZentrum GFZScientific Technical Report STR 10/07
DOI: 10.2312/GFZ.b103-10079


























ii
Deutsches GeoForschungsZentrum GFZScientific Technical Report STR 10/07
DOI: 10.2312/GFZ.b103-10079Abstract


The Lombok Island is part of the Lesser Sunda Islands (LSI) region – Indonesia,
situated along the Sunda-Banda Arcs transition. It lies between zones characterized
by the highest intensity geomagnetic anomalies of this region, remarkable as one of
stthe eight most important features provided on the 1 edition of World Digital
Magnetic Anomaly Map. The seismicity of this region during the last years is high,
while the geological and tectonic structures of this region are still not known in detail.
Some local magnetic surveys have been conducted previously during 2004–2005.
However, due to the lower accuracy of the used equipment and a limited number of
stations, the qualities of the previous measurements are questionable for more
interpretations. Thus a more detailed study to better characterize the geomagnetic
anomaly -spatially and temporally- over this region and to deeply explore the related
regional geology, tectonic and seismicity is needed. The intriguing geomagnetic
anomalies over this island region vis-à-vis the socio-cultural situations lead to a study
with a special aim to contribute to the assessment of the potential of natural hazards
(earthquakes) as well as a new natural resource of energy (geothermal potential).

This study is intended to discuss several crucial questions, including:
i. The real values and the general pattern of magnetic anomalies over the island, as
well as their relation to the regional one.
ii. Any temporal changes of regional anomalies over the recent time.
iii. The relationships between the anomalies and the geology and tectonic of this
region, especially new insights that can be gained from the geomagnetic
observations.
iv. The relationships between the anomalies and the high seismicity of this region,
especially some possible links between their variations to the earthquake
occurrence.

First, all available geomagnetic data of this region and results of the previous
measurements are evaluated. The new geomagnetic surveys carried out in 2006 and
2007/2008 are then presented in detail, followed by the general description of data
processing and data quality evaluation. The new results show the general pattern of
contiguous negative-positive anomalies, revealing an active arc related subduction
region. They agree with earlier results obtained by satellite, aeromagnetic, and
marine platforms; and provide a much more detailed picture of the strong anomalies
on this island. The temporal characteristics of regional anomalies show a decreasing
strength of the dipolar structure, where decreasing of the field intensities is faster
ththan the regional secular variations as defined by the global model (the 10
generation of IGRF). However, some exceptions (increasing of anomalies) have to be
noted and further analyzed for several locations.

Thereafter, simultaneous magnetic anomalies and gravity models are generated and
interpreted in detail. Three profiles are investigated, providing new insights into the
tectonics and geological evolution of the Lombok Island. Geological structure of this
island can be divided as two main parts with different consecutive ages: an old part
(from late Oligocene to late Miocene) in the South and a younger one (from Pliocene to
Holocene) in the North. A new subduction in the back arc region (the Flores Thrust
zone) is considered mature and active, showing a tendency of progressive subduction
during 2005–2008. Geothermal potential in the northern part of this island can be
iii
Deutsches GeoForschungsZentrum GFZScientific Technical Report STR 10/07
DOI: 10.2312/GFZ.b103-10079mapped in more detail using these geomagnetic regional survey data. The earlier
estimates of reservoir depth can be confirmed further to a depth of about 800 m.
Evaluation of temporal changes of the anomalies gives some possible explanations
related to the evolution of the back arc region, large stress accumulations over the LSI
region, a specific electrical characteristic of the crust of the Lombok Island region, and
a structural discontinuity over this island.

Based on the results, several possible advanced studies involving geomagnetic data
and anomaly investigations over the Lombok Island region can be suggested for the
future:
i. Monitoring the subduction activity of the back arc region (the Flores Thrust zone)
and the accumulated stress over the LSI, that could contribute to middle term
hazard assessment with a special attention to the earthquake occurrence in this
region. Continuous geomagnetic field measurements from a geomagnetic
observatory which can be established in the northern part of the Lombok Island
and systematic measurements at several repeat stations can be useful in this