# Analysis of Information Availability for Seismic and Volcanic Monitoring Systems: A Review
## 1 Introduction
The information availability requires that the service must be ready for the user (people, processes, and applications) [14] when needed and with authorization; therefore, the information system components must be in operation and avoid service interruptions, hardware failures, communications, and power outages [12]. Nonetheless, availability from an information security perspective considers the loss and/or acceptable data interruption in a specified  
Figure 1: Seismic-volcanic monitoring systems. A general diagram. period. High availability and redundancy systems can detect failures and minimize such disruption [15], among others. Organizations responsible for seismic and/or volcanic studies worldwide (SDCs) have \"seismic data\" as their primary information asset to determine early warnings [2; 16]. These data are generated by the instrumental monitoring networks and carried over different transmission media toward the data centers. Subsequently, data are received in acquisition and processing systems. Then, they are stored for use in the information interpretation and diffusion processes, as well as future phenomenon research. For example, in these studies [17; 18; 19], even though organizations are different and have seismic monitoring responsibilities or volcanic monitoring, they have similarities in their structure for information processing. At communication systems for seismic and volcanic monitoring, the most compromised component of the information security triad is availability. Therefore, this study is motivated by the availability vulnerabilities, the possible risks of communication outages that affect data quality, its incidence on early warnings, and response times. The goal is to propose an information security strategy with mechanisms for increasing the availability of information in instrumental networks and their interaction with acquisition and processing systems inside SDCs. Therefore, the study does not focus on risk management and possible seismic-volcanic impacts on the population, impacts on human lives, and risks for the population. The diversity of worldwide seismic and volcanic monitoring networks has been considered in this review, due to seismic and/or volcanic monitoring centers being structured in blocks or similar processes that include: measurement of seismic-volcanic activity, data transmission, acquisition, processing, analysis, interpretation, and diffusion of information. The literature review in this research will summarize the most important methods and solutions that contribute to the availability of information in data acquisition systems and data transmission networks for seismic and volcanic monitoring. In this way, this work relates to recent studies, mainly since 2015, on the most recommended protocols and algorithms for recognizing factors that affect the real-time transmission, data recovery processes, and the information from instrumental networks designed for geological phenomena monitoring. This article review criterion is due to software updates for acquisition systems and features of current models of sensors, digitizers, and transmission media used in seismic-volcanic monitoring networks. Section 2 introduces the methodology, including research questions, search strategies, study selection, study quality assessment, data collection, and data analysis to achieve a summary of relevant studies. Section 3 reviews seismic studies and results about instrumental networks, data acquisition and processing, seismic data standards, and early warning trends. Section 4 provides an analysis of the proposed research questions. Finally, Section 5 concludes the research findings in this literature review, the threats to data acquisition systems and seismic monitoring networks, and possible future solutions.