suddenly dead trees, some splitting open

Question

We have had a number of well established trees die this past year.
After several years of drought we had an exceptionally wet winter. No hard freezing here.
We have lost redwoods, poplar/cottonwoods, Italian cypress, willow, fig (black) and fig (white).All died seemingly spontaneously.
The fig trees, now dead, are splitting open on the trunks and limbs.

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Answer 1

These trees are dead - past "tracing".
The cracks were not caused by freezing- as in "frost cracks" and it is the trunks, so not "bark splitting" either.

Answer 2

This is likely caused by the fluctuation in the environmental conditions you mention.
Wounds should not be covered; there is a technique called tracing, that is explained in the links below.
You can also check with your County Extension Office, they may have specific care to your region.

http://plantclinic.cornell.edu/factsheets/barksplitting.pdf
https://www.gardeningknowhow.com/ornamental/trees/tgen/cracking-tree-trunks.htm
https://www.oakgov.com/msu/Documents/publications/oc0476_bark_splitting.pdf
https://www.gardeningknowhow.com/extension-search/