 |
| Titel |
Rethinking moment tensor inversion methods to retrieve the source mechanisms of low-frequency seismic events |
| VerfasserIn |
Sandra Karl, Juergen Neuberg, Thomas Roome |
| Konferenz |
EGU General Assembly 2011
|
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250053064
|
|
|
|
|
|
| Zusammenfassung |
| Forecasting volcanic eruptions is a fundamental objective of volcanology. In recent years,
the study of volcano seismic signals has grown in importance and has resulted in
significant advances towards the understanding of the internal dynamics of active
volcanic systems. However, the potential to use these signals for better forecasting the
eruptive behaviour of volcanoes is somewhat limited, unless a better understanding
of the exact role of the trigger mechanisms in a wider volcanological context is
gained.
Long period (LP) seismic events are one class of volcano seismic earthquakes that have
been observed at many volcanoes around the world, and are thought to be associated
with resonating fluid-filled conduits or fluid movements (Chouet, 1996, Neuberg et
al.). While the seismic wavefield is well established, the actual trigger mechanism
of these events is still poorly understood. In an attempt to better understand the
driving forces of LPs, inversions for source mechanisms have become increasingly
common.
This approach uses synthetic LP seismograms to invert for source mechanisms on
Souffriere Hills volcano using a moment tensor (MT) inversion procedure. The receiver
distribution represents the real distribution as it is installed and active on Montserrat island.
The synthetic seismograms generated represent the free surface response to a chosen source
embedded in a homogeneous half space with vp = 3.5km-s, vs = 1.86km-s, and
Ï = 2.32kg-m3. The source mechanism for this study, slip on a ringfault structure at a
realistic depth, was approximated by a set of 8 double couple sources in an octagonal
arrangement.
Previous studies have commonly assumed a point source for waveform inversion.
Knowing that applying a point source model to synthetic seismograms representing an
extended source process does not yield the real source mechanism, it can, however, still lead
to interesting results. Therefore, this study investigates the effects of changing the
source parameters on the apparent moment tensor elements. In future, point source
inversion based on higher-order tensors might have to be considered to improve our
understanding of the source mechanisms of low-frequency earthquakes in volcanic settings. |
|
|
|
|
|
|