There is a drug presence among people living on the streets and in the bars. This means that panhandling can be a problem. Panhandlers are aggressive despite laws against this behaviour. You may wish to avoid Pandora Street between Cook and Quadra as this is where a huge majority hang out. Do not walk around parks and grassy areas in sandals or bare feet as there are many needles discarded in these areas, city workers are quick to clean them up but it is always a good idea to be precautious in these areas. However there is a strong police presence on downtown streets during the summer, especially on weekends at night. This problem is generally confined to the tourist area bounded by Blanshard Street.
Because all the bars and clubs are very close together, many drunken people spill into the streets at 2AM on Thursday, Friday, and Saturday night and are in fact more dangerous than the street people. If you are out and about at this time or have your downtown hotel room window open be prepared to deal with all that drunken idiots have to offer such as public urination, shouting and rude comments.
In the unlikely event of a major earthquake, duck and cover and stay where you are during the shaking, then go outside once the shaking stops. Buildings and other structures are unlikely to collapse. Your largest threats come from breaking windows and falling objects such as ceiling tiles and bookshelves. Try to get under a table, desk, or door jam to reduce your exposure to these threats. You are more likely to be injured if you try to run during the shaking.