Southern California is ... unique. I grew up down there, along with several tens of millions of other people, and I watched my town grow from a little community of 20,000 people to something like 100,000 when I left thirty years ago. I've had occasion to return more than a few times and I see seven or eight cities which have merged and overlapped to form an urban center that isn't called Los Angeles or San Diego, yet has more than 2 million people. They have to live somewhere, and that's forced many to live in places that have to be considered sort of marginal.
In my high school days, I ran cross country, and we trained in the foothills and across the alluvial fans at the base of the San Gabriel Mountains beneath Cucamonga and Ontario Peaks (8,859 and 8,693 feet respectively). I liked exploring the chaparral country, especially after the spring rains, and in those days, the fans were undeveloped. They were considered sort of a wasteland, too rocky to grow citrus or graze cows, as was done in the flatter valleys below.
It was quite a shock, then, to visit some relatives who lived in one of the newer developments, tucked right up against the mountains. In many third-world countries, people live in the marginal environments in shanties. In Southern California, they live in two story mansions.
So here are my questions for the day: How many natural hazards can people in the developments above, at the base of the eastern San Gabriel Mountains, reasonably expect to experience at some point in their lives? What is the geological cost of living in beautiful Southern California? And how many of these hazards are spelled out in the mortgage papers these folks sign?