To create a disaster more randomly, you can you .... RANDOM !
TethysGame::GetRand(maxvalue) returns a random (integer) value between 0 and maxvalue-1. You can use this for the co-ordinates, as well as the timing:
This creates a meteor at a random location, somewhere in the region (1,10) - (128,41):
TethysGame::SetMeteor(32+TethysGame::GetRand(128),10+TethysGame::GetRand(32),1);
Remember: you have to add 31 to the location, so the first random creates values between 32 and 159 which translates to 1 .. 128.
To start these disasters at a random interval:
CreateTimeTrigger( 1, 0, 300, 800, "Meteor" );
OP2 will start the trigger at a random time somewhere between 300 and 799. Then when it fires, it again creates a random time. It doesnt "store" the result, to use it over and over. If the first trigger starts at mark 4 (=400), this doesnt mean the second WILL start at 8. It CAN, but it is more likely to start at some other time.