Colombian authorities are working with Pacific Rubiales Energy Corp. to investigate an increase in seismic activity in the nation’s biggest oil-producing area. The Colombian Geological Service, or SGC, is looking into possible causes of a rise in the number of tremors in eastern Meta province, where the country’s second-biggest oil company has its main operations, SGC geologist Marta Lucia Calvache said by telephone this week. Opposition Sen. Jorge Enrique Robledo and an oil workers’ union are blaming Pacific Rubiales’s Synchronized Thermal Additional Recovery, or STAR, technology, for the increase, an allegation the company says is unfounded. STAR is designed to increase flows by igniting oil in the well. “The hypothesis is that the...