Regarding the request from philshem in the comments to the question, I will post my comment details as an answer.
Disclosure: I am the author of the mentioned website.
As a suggestion, as I feel it fits the question and this was migrated from softwarerecs: Currently, I am getting emergency location data up and running and have recently added wildfires and earthquakes as WMS. The services are not free though (services need to be maintained) but the respective data is open data.
If you'd like to put it into a cool map app, I'm open to discussing usage options like free use for non-commercial applications. You also might be able to find more data here: www.geodata.one.
The data contents include e.g. major volcanic eruptions, major tsunami locations (World); current river water levels, wind speed/ direction, rainfall amount, temperature, severe weather warnings, current radiation values (Germany).
Some of the data services are external, some still need to be set up or updated. If there is more relevant data out there, I will definitely add them (suggestions welcome).