Complex sentence: The storm caused a serious disruption throughout the entire municipality during the first week of October; although some areas of the urban core only lost electricity for a brief period, outlying rural regions in the eastern part of HRM were without electricity for up to two weeks.
Split into simpler sentences: The storm caused a serious disruption throughout the central and eastern part of the municipality during the first week of October. Although some areas of the urban core only lost electricity for a brief period, outlying rural regions in the eastern part of HRM were without electricity for up to two weeks.