Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)The South America VLF Network (SAVNET) has been installed in April 2009, and is composed of eight tracking receivers spread over South America, in Brazil, Peru and Argentina, and the Antarctica Peninsula. SAVNET is monitoring the properties of subionospheric propagating waves that reveal changes of the electrical properties of the ionospheric diurnal D-region or nocturnal E-region. In this paper, we will show the ability of the diagnostic obtained by SAVNET to discuss the monitoring of the solar activity on short timescales related to ionization due to solar flares. The sensitivity of flare detection as a function of the solar activity level will be discussed. On longer timescales related to the solar cycle, SAVNET is also able to provide information on the solar Lyman-alpha radiation. Finally we show that the VLF technique is well suited to search for of seismic-electromagnetic effects, and to provide a genuine diagnostic of high-energy astrophysical phenomena. (C) 2010 Elsevier Ltd. All rights reserved.7341984SI15811586MACKPESQUISAConselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Centre National de la Recherche Scientifique (CNRS)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)CNPq [Proc. 304433/2004-7, 490124/2006-2]FAPESP [Proc. 2007/05630-1, Proc. 06/02979]