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| Titel |
Constructing new seismograms from old earthquakes: Retrospective seismology at multiple length scales |
| VerfasserIn |
Elizabeth Entwistle, Andrew Curtis, Erica Galetti, Brian Baptie, Giovanni Meles |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250106629
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| Publikation (Nr.) |
 EGU/EGU2015-6307.pdf |
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| Zusammenfassung |
| If energy emitted by a seismic source such as an earthquake is recorded on a suitable
backbone array of seismometers, source-receiver interferometry (SRI) is a method that allows
those recordings to be projected to the location of another target seismometer, providing an
estimate of the seismogram that would have been recorded at that location. Since the other
seismometer may not have been deployed at the time the source occurred, this renders
possible the concept of “retrospective seismology” whereby the installation of a sensor at one
period of time allows the construction of virtual seismograms as though that sensor had been
active before or after its period of installation. Using the benefit of hindsight of earthquake
location or magnitude estimates, SRI can establish new measurement capabilities
closer to earthquake epicenters, thus potentially improving earthquake location
estimates.
Recently we showed that virtual SRI seismograms can be constructed on target sensors in
both industrial seismic and earthquake seismology settings, using both active seismic sources
and ambient seismic noise to construct SRI propagators, and on length scales ranging over 5
orders of magnitude from ~40 m to ~2500 km[1]. Here we present the results from
earthquake seismology by comparing virtual earthquake seismograms constructed at target
sensors by SRI to those actually recorded on the same sensors. We show that spatial
integrations required by interferometric theory can be calculated over irregular
receiver arrays by embedding these arrays within 2D spatial Voronoi cells, thus
improving spatial interpolation and interferometric results. The results of SRI are
significantly improved by restricting the backbone receiver array to include approximately
those receivers that provide a stationary phase contribution to the interferometric
integrals. We apply both correlation-correlation and correlation-convolution SRI, and
show that the latter constructs virtual seismograms with fewer non-physical arrivals.
Finally we reconstruct earthquake seismograms at sensors that were previously active
but were subsequently removed before the earthquakes occurred; thus we create
virtual earthquake seismograms at those sensors, truly retrospectively. Such SRI
seismograms can be used to create a catalogue of new, virtual earthquake seismograms that
are available to complement real earthquake data in future earthquake seismology
studies.
[1]E. Entwistle, Curtis, A., Galetti, E., Baptie, B., Meles, G., Constructing new
seismograms from old earthquakes: Retrospective seismology at multiple length scales, JGR,
in press. |
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