Exploding manholes are one of those weird and interesting side effects of living in a large city. Imagine walking down the street when all of a sudden a manhole covers flies 50 feet in the air!
Greenhouse gases, CFCs, oil guzzling cars and smoke-belching industry. We don't lack examples of environmental threats that have occupied the previous generations.
Earthquakes are "natural" disasters, right? Yes, but that doesn't mean the shifting plates that cause them can't be aggravated by human industry.