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Ghost tilt signal during transient ground surface deformation events: Insights from the September 3, 2010 Mw7.1 Darfield earthquake, New Zealand
Author(s) -
Fournier Nicolas,
Jolly Arthur D.,
Miller Craig
Publication year - 2011
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2011gl048136
Subject(s) - geology , tilt (camera) , seismology , deformation (meteorology) , transient (computer programming) , signal (programming language) , geodesy , oceanography , geometry , mathematics , computer science , programming language , operating system
This work assesses whether tiltmeters can reliably measure ground tilt in the 2–20 s band, similar to that of very–long period volcanic earthquakes. Seismic waves recorded with co–located high–rate GPS, borehole seismometer and bubble tiltmeter during the 2010 Mw7.1 Darfield earthquake in New Zealand are used to determine the response of the tiltmeter. The joint analysis of this dataset shows that, at least for periods within the aforementioned band, the observed tilt signal was in fact not related to ground tilt but, instead, to translational ground acceleration caused by passing S and surface waves. If no independent control on translational motion is provided for recorded very–long period volcanic earthquakes within the 2–20 s band, the signal recorded on bubble tiltmeters may therefore be misinterpreted. The use of co–located high–rate GPS data provides such control and is essential to discriminate translational motion from ground tilt on the recorded seismic and tiltmeter signals.