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Blockchain is the technology used by developers of cryptocurrencies, like Bitcoin, to enable exchange of financial “coins” between participants in the absence of a trusted third party to ensure the transaction, such as is typically done by governments. Blockchain has evolved to become a generic approach to store and process data in a highly decentralized and secure way. In this article, we review blockchain concepts and use cases, and discuss the challenges in using them from a governmental viewpoint. We begin with reviewing the categories of blockchains, the underlying mechanisms, and why blockchains can achieve their security goals. We then review existing known governmental use cases by regions. To show both technical and deployment details of blockchain adoption, we study a few representative use cases in the domains of healthcare and energy infrastructures. Finally, the review of both technical details and use cases helps us summarize the adoption and technical challenges of blockchains. 

Major earthquakes (>∼6.5 M_w) can generate observable waves which propagate not only through the Earth but also through the Earth's ionosphere. These traveling ionospheric disturbances can be observed using multifrequency GPS receivers to measure the ensuing perturbations in the Total Electron Content of the ionosphere. Assisted by a statistical approach we developed to indicate the occurrence of a significant TEC perturbation from the normal background behavior, we detect a traveling ionospheric disturbance generated by the 2016 7.8M_wKaikoura earthquake occurring in New Zealand on the 13th of November. The disturbance was detected ∼8 min after the earthquake, propagating toward the equator at ∼1 km/s with a peak‐to‐peak amplitude of ∼0.22 Total Electron Content units. The coseismic waveform exhibits complex structure unlike that of the expected N‐wave for coseismic ionospheric disturbances, with observations of oscillations with 4‐min periodicity and of two N‐waves. This observed complexity in the ionosphere likely reflects the impact of the complex, multifault structure of the earthquake.