In an 81-day period during the summer of 1969 four portable seismographs were operated in northwest British Columbia and southeast Alaska. One hundred and forty microearthquakes were detected. Epicenters were located near the Queen Charlotte-Fairweather fault and the Denali fault. The Chatham Strait fault showed no activity and only a few events were located in the Quaternary volcanic zone of British Columbia. A scattering of microearthquakes through the archipelago and the Coast Range and a concentration in the Glacier Bay region suggest that the seismicity may be more complex than the pattern indicated by the distribution of larger earthquakes. The most numerous seismic events recorded, numbering in the thousands, were low-frequency events emanating from a number of specific areas where large glaciers are located.