  This article demonstrates the possibility of constructing indicators of
critical and crisis phenomena in the volatile market of cryptocurrency. For
this purpose, the methods of the theory of complex systems such as recurrent
analysis of dynamic systems and the calculation of permutation entropy are
used. It is shown that it is possible to construct dynamic measures of
complexity, both recurrent and entropy, which behave in a proper way during
actual pre-crisis periods. This fact is used to build predictors of crisis
phenomena on the example of the main five crises recorded in the time series of
the key cryptocurrency bitcoin, the effectiveness of the proposed
indicators-precursors of crises has been identified.
