Ricerc@Sapienza

The goal of this article is the illustration of the newfunctionalities of the VADASE (Variometric Approach for Displacements Analysis Stand-alone Engine) processing approach. VADASE was presented in previousworks as an approach able to estimate in real time the velocities and displacements in a global reference frame (ITRF), using high-rate (1 Hz or more) carrier phase observations and broadcast products (orbits, clocks) collected by a stand-alone GNSS receiver, achieving a displacements accuracy within 1-2 cm (usually better) over intervals up to a few minutes.

It is well established that earthquakes can trigger atmospheric waves able to propagate right up to the ionosphere as
Coseismic Ionospheric Disturbances (CIDs). They are due to the acoustic waves both produced in the proximity of
the epicenter (within 500 km) and by those triggered by Rayleigh waves propagating far from it. Numerous studies
demonstrated that GNSS (Global Navigation Satellite System) is a mean to detect ionosphere alterations through
computing the total electron content (TEC) value.

High-frequency geodesy is here intended as the capability of retrieving information relevant to geodesy and geophysics at high frequency through geodetic measurements and methodologies. In particular, this short review work focuses on two aspects: fast ground motions, as those due to earthquakes, and fast ionospheric total electron content (TEC) disturbances, as those caused by tsunamis.

The number of Android devices enabling access to raw GNSS (Global Navigation Satellite System) measurements is rapidly increasing, thanks to the dedicated Google APIs. In this study, the Xiaomi Mi8, the first GNSS dual-frequency smartphone embedded with the Broadcom BCM47755 GNSS chipset, was employed by leveraging the features of L5/E5a observations in addition to the traditional L1/E1 observations. The aim of this paper is to present two different smartphone applications in Geoscience, both based on the variometric approach and able to work in real time.