Hello Luke,

You should use the circular portion of the prediction input form. You need to establish a center point for the 50 Km circular. A 50 Km circular is actually 100 Km in diameter and contains 7,854 square Km. Given the size of San Jose, you are still being fuzzy about the precise area you are predicting for. South San Jose? North San Jose? Best to get the exact center point. I know others who use geographical names for predictions, like "northern California" or "Baja".
Doesn't say much about where they think the quake will occur. Besides, I view those kind of predictions as cheating. I know you are not into that.

Best of Luck,
Glen