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| Titel |
A seismic wave propagation study for the triggering of the Lusi mud-volcano, Indonesia. |
| VerfasserIn |
M. Lupi, E. H. Saenger, F. Fuchs, S. A. Miller |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250066851
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| Zusammenfassung |
| A long-standing debate began in May 2006 with the onset of the eruption of the Lusi mud
volcano, near Sidoarjo, Indonesia. The controversy concerns the causes that initiated the
discharge of the mud: was it triggered by the nearby drilling operations or was it caused by
the occurrence of a M6.3 seismic event near Yogyakarta?
To shed light on the effects induced by the Yogyakarta earthquake we performed numerical
investigations on the effects induced by the propagation of the seismic waves induced by this
seismic event. To perform the analysis we used a finite-differences grid, which represents the
first 3000 m of crust underneath Lusi. Our geological model is based on seismic profiles,
geological logs and accounts for compressional wave speed, shear wave speed, and
density of the geological layers. An important feature of the geological model is the
occurrence of a relatively high P-wave velocity layer (approximately 6300 m s-1
located approximately 500 m above the geological formation that originated the
mud.
We assumed a fundamental signal frequency of 0.5 Hz to calculate the maximum
energy density distribution in the geological media and we performed seismic wave
propagation analysis for three different sources: i) a plane P-wave arriving from depth,
ii) a point source at the surface, iii) a point source located approximately 1000 m
below the relatively high p-wave velocity layer. The first and the third case lead to
similar results that indicate the occurrence of high energy density concentrations
above and below the high velocity layer. The second case shows that a pure surface
wave would not induce high energies below the relatively high p-wave velocity
layer.
Our analysis shows that the relatively high P-wave velocity layer is key to understand the
whole system. In addition, the simulations indicate that a wave that may have triggered the
onset of the mud volcano could only have been a body wave coming from depth. Future
simulations will include other geological structures, including faults, to determine under what
conditions energy traps may have amplified the seismic energy within the mud layer. |
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