North Korea maintains nearly 6,000 artillery systems within range of major South Korean population centers, which it could use to kill many thousands in just an hour, even without resorting to chemical or nuclear weapons. Researchers assessed the magnitude of this threat across five attack scenarios, using estimates of the number of North Korean artillery systems, the population densities of potential target areas, and assumptions about the locations of people at the time of the attacks (outdoors, indoors, and below ground). The strike scenarios assessed were (1) five minutes against a major industrial target, (2) one minute along the DMZ, (3) one minute against downtown Seoul, (4) one hour along the DMZ, and (5) one hour against downtown Seoul. Estimated total casualties from the attacks ranged from about 4,500 to more than 200,000. The authors conclude that because so much harm could be done so quickly, the United States and South Korea should try to avoid military provocation cycles that could lead to these attacks. This document presents a series of visualizations that helps bring into sharp relief the danger posed by this threat, providing a useful tool for defense leaders, policymakers, and the public in understanding this important aspect of the complex situation on the Korean peninsula.