Tried the Mine bloc, if you leave everything eplodes like a creeper with many damages and a big hole in the ground.
However some player do not want to have their fields around their base filled with holes like the moon.
Si we protected bloc damages : (with worldguad or with a precious stone bloc). this is working, mine explodes, ground is not destroy but damages to players are 10 or 15x less as before?

You can change the intensity mine, by using a different multiplier in the config in the mine flag:

http://preciousstones.shoutwiki.com/wiki/Field_Flag_Reference#mine