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Marzario, Monica
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Marzario, Monica
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- PublicationOpen AccessVery high rate (10 Hz) GPS seismology for moderate-magnitude earthquakes: The case of theMw6.3 L'Aquila (central Italy) event(2011)
; ; ; ; ; ; ; ; ; ; ;Avallone, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia ;Marzario, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia ;Cirella, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Piatanesi, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Rovelli, A. ;Di Alessandro, C. ;D'Anastasio, E. ;D'Agostino, N.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia ;Giuliani, R.; Dipartimento Protezione Civile ;Mattone, M.; Dipartimento protezione civile; ; ; ; ; ; ;; ; The 2009 April 6th Mw 6.3 L'Aquila destructive earthquake was successfully recorded by closely 23 spaced 10-Hz and 1-Hz recording GPS receivers and strong motion accelerometers located above or 24 close to the 50° dipping activated fault. We retrieved both static and dynamic displacements from 25 Very High-Rate GPS (VHRGPS) recordings by using Precise Point Positioning kinematic analysis. 26 We compared the GPS positions time series with the closest displacement time series obtained by 27 doubly-integrating strong motion data, first, to assess the GPS capability to detect the first seismic 28 arrivals (P waves) and, secondly, to evaluate the accelerometers capability to detect co-seismic 29 offsets up to ~45 s after the earthquake occurrence. By comparing seismic and VHRGPS frequency 30 contents, we inferred that GPS sampling rates greater than 2.5 Hz (i.e. 5 or 10 Hz) are required in 31 the near-field of moderate magnitude events to provide “alias-free” solutions of coseismic dynamic 32 displacements. Finally, we assessed the consistency of the dynamic VHRGPS results as a constraint 33 on the kinematic rupture history of the mainshock. These results suggested that the high-rate 34 sampling GPS sites in the near field can be as useful as strong motion station for earthquake source 35 studies.389 513 - PublicationOpen AccessThe 2009 L'Aquila Earthquake: Postseismic Deformation with High Temporal Resolution Using the new GPS "Carrier Range" Data Type(2009-12)
; ; ; ; ; ;D'Anastasio, Elisabetta; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia ;Blewitt, Geoffrey; Bureau of Mines and Geology/ Seismological Laboratory, University of Nevada, Reno, NV, USA ;D'Agostino, Nicola; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia ;Avallone, Antonio; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia ;Cheloni, Daniele; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Marzario, Monica; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia; ; ; ; ; ; ; ;Eos Trans. AGU; American Geophysical UnionThe availability of continuous GPS measurements during or soon after significant (Mw > 6) seismic events is important to record the coseismic displacements, the initial postseismic evolution and to evaluate their relative contribution to the overall crustal deformation and total moment release (both seismic and aseismic). Here we present the result of the analysis of continuously operating GPS permanent stations already active or rapidly deployed after the Mw 6.3 2009 April 6th L'Aquila earthquake. In contrast to the observations made for previous earthquakes in Italy, our observations capture the 2009 mainshock allowing an improved temporal resolution on the early postseismic deformation. In order to better define initial postseismic displacements and investigate sub-daily station motions we calculate epoch-by-epoch (0.1 - 30 sec) position time series with the new "carrier range" data type based on the JPL GIPSY-OASIS package. This new approach is based on the calibration of carrier phase data of each station using estimates of one-way carrier phase biases from an ambiguity-fixed network of ~3,500 stations worldwide [see Blewitt, Bertiger and Weiss, 2009 Fall AGU Meeting]. Carrier range data (a precise pseudorange data type) were constructed for GPS stations in the epicentral area, and were processed without carrier phase bias estimation. Time-dependent postseismic displacements were then modeled with a logarithmic time-dependent function. Since postseismic deformation begins immediately after the mainshock and is large within the first day following the mainshock, the actual estimate of amount of coseismic deformation depends upon the temporal character of the deformation and the availability of high-rate GPS time series immediately after the mainshock. The results of our analysis are then used to characterize the characteristics of the initial postseismic evolution after the 2009 mainshock and to investigate the time-dependent distribution of afterslip on the fault.344 105