Online detection of offsets in GPS time series
- PDF / 3,966,975 Bytes
- 10 Pages / 595.224 x 790.955 pts Page_size
- 39 Downloads / 188 Views
RESEARCH ARTICLE
Online detection of offsets in GPS time series A case study of eruptive fissure opening at Mount Etna Giuseppe Nunnari1
· Flavio Cannavo´ 2
Received: 18 November 2019 / Accepted: 25 August 2020 © The Author(s) 2020
Abstract This paper deals with the online offset detection in GPS time series recorded in volcanic areas. The interest for this problem lies in the fact that an offset can indicate the opening of eruptive fissures. A Change Point Detection algorithm is applied to carry out, in an online framework, the offset detection. Experimental results show that the algorithm is able to recognize the offset generated by the Mount Etna eruption, occurred on December 24, 2018, with a delay of about 4 samples, corresponding to 40 min, compared to the best offline detection. Furthermore, analysis of the trade-off between success and false alarms is carried out and discussed. Keywords Volcano monitoring · Eruptive fissures · Offsets in GPS time-series
Introduction The Global Positioning System (GPS) has become an essential tool for ground deformation monitoring in environments subject to the risks of natural disasters, such as active volcanic and tectonic areas. Fast detection of potentially hazardous events (such as earthquakes and volcanic eruptions), can be decisive for safeguarding human lives and infrastructures. However, data available in real time by GPS monitoring networks are not themselves enough for a reliable evaluation of the phenomena in progress, unless appropriate analysis tools be available too. One of the problems that prevent an effective use of GPS sub-daily solutions for real time applications, is that they are usually affected by a significant amount of noise due to different sources of uncertainty (e.g. Communicated by: H. Babaie Giuseppe Nunnari
[email protected] Flavio Cannav´o [email protected] 1
Dipartimento di Ingegneria Elettrica Elettronica e Informatica, Universit´a degli Studi di Catania, Viale A. Doria, 6, 95125 Catania, Italy
2
Istituto Nazionale di Geofisica e Vulcanologia, Piazza Roma, 2, Catania, Italy
non-precise ephemerides). In particular, the shorter the processed period, the higher the level of noise affecting the GPS solutions. Thus, the algorithms for detecting true displacement transients must be as robust as the sampling time is lower. Due to the large number of noise sources, often not well known, GPS noise is generically modeled as a mixture of white noise, flicker noise and random walk noise (Mao et al. 1999). Offsets are one of the components of GPS time series, sometimes considered as a source of noise, which could contribute to degrade the accuracy of GPS time series. They can be due to the equipment problems, such as antenna or receiver changes, but also to natural phenomena, such as post seismic effects of earthquakes and, in volcanic areas, to the opening of eruptive fissures. Offsets can have various sizes, from very small, which are very difficult to detect in presence of noise, to quite large, which, on the contrary, ca
Data Loading...
