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Conference Papers Year : 2011

Modelling LP source process at Ngauruhoe volcano, New Zealand


Ngauruhoe volcano has produced over 20000 small repeating long period earthquakes since 2006. The earthquakes are characterised by extended codas, a small range in magnitudes (all < ML 1.5) and nearly identical waveform characteristics over long time-periods (years). These persistent earthquakes were observed to change over a two week period in January 2008; A period when the two station permanent network at Ngauruhoe was augmented by 3 additional temporary broad-band sensors. In the frequency domain, the earthquakes became higher frequency, while retaining some of the main resonant peaks (i.e. 1.2, 3.2 and 4 Hz) from the earlier period of the sequence. In the time domain, the waveform envelope retained some of their characteristic phases, but had notably higher frequencies. These changes occurred without any systematic shift in relative phase arrival times (i.e. locations), and so occurred within a small source volume. We will present results of forward and inverse waveform modelling for two earthquakes, one dominated by low frequencies and the other with more broader frequency characteristics. For our modelling, we use a visco-elastic finite-difference method to compute Green's functions in a range of spatial locations around Ngauruhoe volcano. These impulse responses are then used to invert for the source moment assuming various source orientations, geometries and positions. Our objective is to discover possible property changes, whether source position, geometry, or source orientation, which might have produced the observed changes within the time and spatial constraints for the two modelled earthquakes.
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Dates and versions

hal-00599190 , version 1 (08-06-2011)


  • HAL Id : hal-00599190 , version 1


A. Jolly, Philippe Jousset, J. Neuberg, Steve Sherburn. Modelling LP source process at Ngauruhoe volcano, New Zealand. 2011 International Union of Geodesy and Geophysics (IUGG) General Assembly, Jun 2011, Melbourne, Australia. ⟨hal-00599190⟩


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