# Analysis of Information Availability for Seismic and Volcanic Monitoring Systems: A Review
## 1 Introduction  
Commonly, seismological data centers (SDC) around the world are continually adding new technologies for data acquisition and processing, data storage, information analysis, and information diffusion. So, SDCs have reached their current monitoring networks by increasing instrumental networks and repeater nodes of different capabilities at different stages. Instrumental networks of SDCs consist of various sensor types such as seismic sensors, accelerometers, inclinometers, high-precision GPS, monitoring cameras, pressure sensors, infrasound sensors, gas measurement sensors, and others [1, 2, 3]. These specialized sensors require other components such as data acquisition systems, data loggers,transmission media, energy sources, and physical infrastructure. Once new sensing data are generated, they are sent in continuous mode or time intervals, mainly using TCP/IP protocol stack through a data transmission media assigned to each terminal station. Communication media used commonly in SDCs are microwave, satellite, Wi-Fi, optical fiber, 3G/4G network, and the Internet [4; 5]. Some network topologies combine communication media by using repeaters nodes until reaching SDC. These centers host the acquisition, processing, and storage systems for real-time monitoring, analysis, diffusion, and other processes [6]. Sometimes, data transfer is discontinuous because of internal or external factors. Among the latter case, radio frequency interference and weather conditions are prevalent in wireless links. On the other hand, internal factors are related to the transmission medium's technological limitations, power backup failures, problems associated with the retrieval of information from the acquisition systems, and underused alternative channels in the repeater nodes. For example, IG-EPN (Instituto Geofisico, Escuela Politecnica Nacional, Ecuador) located in South America has annually identified that the overall performance of data transmission networks is not at the best level (less than 90 percent) [7; 8], due to the factors mentioned above and others, such as the diversity of data acquisition systems and manual procedures for the data recovery process used in some SDCs. Figure 1, \"seismic-volcanic monitoring systems: a general diagram\", aims to visualize the involved processes from the source to the users. Where the problem representation contrasts an ideal system in front of a real system, processes could be improved with the contribution of this research This study aims to identify the leading causes that could increase the error range in data acquisition, analysis, and diffusion of information, as well as identify some actions that have been taken to solve these problems on specific seismic-volcanic networks. Currently, SDCs have to process this information with possible accuracy failures or delays in processing time due to data gaps. Information security focuses on the assurance of data systems through the compliance of processes, standards, and mechanisms that improve the confidentiality, integrity, and availability of information, regardless of where it is located. Regarding information availability, operational continuity focuses on information reliability at the source, storage, processing, transmission, or access to information [9]. Operational continuity also includes evaluating risks and threats, establishing action plans, applying standards, implementing good practices that improve the management of information assets, and guaranteeing service continuity [10]. From the information security perspective [11; 12; 13], confidentiality is defined as the characteristic that allows access to information only to authorized users. Integrity refers to ownership to protect data from alterations or modifications unauthorized, and availability considers the timely delivery of data when the authorized user requires it.