Synonyms of the word 
SEISMIC → SEISMAL - UNSTABLE
seismic
- adj. Related to, or caused by an earthquake or other vibration of the Earth.
- adj. (figuratively) Of very large, or widespread effect.
seismal
- adj. seismic.
unstable
- adj. Having a strong tendency to change.
- adj. Fluctuating; not constant.
- adj. Fickle.
- adj. Unpredictable.
- adj. (chemistry) Readily decomposable.
- adj. (physics) Radioactive, especially with a short half-life.
- v. (transitive) To release (an animal) from a stable.
If you are interested in words, visit the following sites :
- wiktionary.org/seismic For complete definition of a word
- 1word.ws/seismic to play with words, suffixs, prefixs, etc.