As a rule, kriyas haTorah is an obligation incumbent on the tzibur. Therefore, a person who lives in a city that does not have a minyan generally does not need to leave his city in search of a minyan to participate in kriyas haTorah. Reading Parshas Zachor (and according to some, Parshas Parah), however, is an obligation on the individual. Therefore, one must try to get to a minyan. If this is not feasible, he must read on his own from a Sefer Torah. According to some Achronim, if a person was unable to hear Parshas Zachor, he can be yotzei his obligation by listening to the kriyas haTorah that is read on Purim day. The kriyah relates the story of Amalek’s attack. Other Achronim say that since these pesukim do not consist of the actual instruction to obliterate Amalek, their recital does not count towards the mitzvah. The poskim disagree about whether women are obligated to listen to Parshas Zachor. The custom for women is to try to listen to the leining.
[שו"ע תרפה, ז, ומשנ"ב יז; ביאורים ומוספים דרשו, 26]