Japan's Balloon Bomb Attacks on North America - a GIS Exercise for Forensic Geology

Japanese balloon bombs started to arrive in the western United States and Canada during November 1944 and continued until July of 1945. Finding the launch site(s) of these balloons is one of the great detective stories of WWII and became one of the earliest and classic cases of forensic geology. Sand in the ballast bags provided the forensic evidence leading to the discovery of the launch sites. Micro-paleontologists and mineralogists in the USGS Military Geology Department examined the sand and eliminated various launch sites on the US & Canadian west coasts and Hawaii, concluding that the balloons had been launched from beach areas in Japan.

I developed a GIS exercise for students to examine various data sets to see how these conclusions were reached. Using Google Earth, students convert selected geographic descriptive locations given by Mikesh (1973) into coordinates. These lat/long values, along with other descriptors, create an Excel spreadsheet of metadata related to each incident. Students bring data into ArcMap as XY data and display it on a global map. Using various fields of metadata, students sort and symbolize the data by incident type, date found, injuries/deaths, and whether ballast sand bags were recovered.

Adding scanned and georeferenced geologic maps from the Japanese Geological Survey and coordinates of the launch sites, students discuss the source areas of the minerals found in the sands. Diatomées fossiles du Japon (1889), which played a major role in the historical identification of microfossils in the sand, adds a wonderful element to the project.

Adding current jet stream pattern maps to ArcMap shows that current jet stream positions during the late fall and winter months correlate very well with the pattern of balloon bomb incidents in the US and Canada.