Programming When North Korea conducted its recent nuclear weapon test, the blast had been detected by a global seismic sensing network operated by the Preparatory Commission for the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO). The network, called the International Monitoring System, aims to “make sure that no nuclear explosion goes undetected.” Software designed in part by a Brown University computer scientist is helping to do just that.The most recent North Korean test wasn’t terribly difficult to detect. It was a fairly large blast, it occurred in a place where a test wasn’t surprising, and the North Korean government made no effort to hide it. But clandestine tests of smaller devices, perhaps by terrorist organizations or other non-state actors, are a different story. It’s those difficult-to-detect events that VISA — a machine learning system that Brown’s Erik Sudderth helped to design — aims to find.The International Monitoring System includes 149 certified seismic monitoring stations around the globe. Those stations send data to the CTBTO’s Vienna headquarters, where analysts compile all seismic events into a daily bulletin supplied to nations around the world. The vast majority of events detected by the system are natural — earthquakes and seismic tremors of various sorts. But…