As a Plum community pauses to remember those who died in a fatal house explosion a year ago, questions about the cause remain unresolved and a mayor is demanding answers.  Six residents in the Rustic Ridge neighborhood died as a result of the massive Aug. 12 explosion, which sent shock waves that were felt throughout the borough and beyond. The blast destroyed three houses and caused significant damage to a dozen more. A house across the street remained standing but eventually had to be razed because it was uninhabitable. Its rebuild is nearly complete.   Read the article…………………………….