I don't see it being that big of deal on a world stage, at least not directly. You don't see a worldwide pump into Chinese markets, it's nearly all internal. It will be interesting to see the pullback on Chinese foreign equity investment and liquidation of whatever percentage of assets this brings about.

That's pretty textbook. Very alarming.

I'm no economist and it looks to me like events like this are pretty well-predicted. My question is: why aren't there measures to prevent these events?

According to the other link that's been posted (article is here: http://www.vox.com/2015/7/7/8910293/china-stock-market-crash), the crash happened as a result of several rounds of increasing restrictions on "trading on margin"; using borrowed money to ride the stock market. Apparently the restrictions were so well-enforced that it actually chopped growth off at the knees, and the market fell into free-fall.

I'm not saying that regulation is bad (it's not), but they clearly went overboard in an attempt to curb their bubble-like growth, and ended up causing the same kind of market contraction they were trying to prevent. Of course, I would assume it's likely that the bust would've been far more dramatic if they had let the bubble find its natural end.