Test site Irpinia
WP 3.4
High Frequency GPS: a potential contribution
for monitoring a active faults
Resp.
Antonio Avallone
M. Marzario, E. D’Anastasio, N. D’Agostino, L. Abruzzese, V. Cardinale,
Castagozzi, G. Cecere, C. D’Ambrosio, G. De Luca, L. Falco, A. Memmolo,
F. Minichiello, F. Migliari, M. Pignone, R. Moschillo, L. Zarrilli
Istituto Nazionale di Geofisica e Vulcanologia, Centro Nazionale Terremoti
Roma, 24 marzo 2010
Objectives
•
Set up of a first dense local CGPS network in Italy
transmitting data in real-time for GPS seismology
studies on a single active fault.
•
Epoch-by-epoch (kinematic) GPS data analysis using a
geodetic-quality software
•
Capability to retrieve quick co-seismic mean
displacements after the earthquake
Real-time CGPS network
Data are acquired at both
1Hz and 30s sampling
intervals and are transmitted
in real time by satellite
telemetry or GPRS/UMTS or
WIFI technologies.
High-rate GPS data analysis (1/2)
Despite traditional GPS data analysis (daily solutions), the high-rate
GPS data analysis is based on processing data in kinematic mode
providing a solution every recorded epoch.
Higher the sampling rate = higher the solution rate
The GPS data analysis has been performed using Gipsy/Oasis II
software (developed at JPL, NASA) with the Precise Point
Positioning strategy
Example of 30s-sampled
GPS time series for the
Sumatra earthquake
Red = North
Green = East
High-rate GPS data analysis (2/2)
Example of 10Hz-sampled
GPS time series for the
L’Aquila earthquake
Red = North
Green = East
Blue = Up
For the first time:
- 10Hz sampled PPP time
series
- GPS sites on the
activated fault (“near
source”)
Sampling rate > 1Hz are
needed tostudy moderate
magnitude events, as
those in the Apennines
Avallone et al., in prep.
Quick co-seismic mean displacement detection
To analyze GPS data, satellite
orbits and clocks are needed.
IGS final orbits and clocks:
available with 12-18 days latency
(every Thursday)
IGS Rapid orbits and clocks:
available with 17-41 hours latency
(daily, at 17 UTC)
Conclusions
We now are able to analyze high-rate GPS data to carry out earthquake
source studies on a seismogenic fault
We now could obtain a quick co-seismic mean displacement detection
within about 1 day from the earthquake, without important loss of
accuracy
For the end of the project, we will:
- investigate the capability of the 10Hz GPS data to detect the main
aftershocks occurred after the L’Aquila mainshock
- Explore the possibility to use IGS Ultra-rapid orbits to reduce the
analysis latency (to about 3-4 hours) (main problem: satellite clock
information are needed but not delivered…)