Digital spatial data for the map "Earthquakes in and near the northeastern United States, 1638-1998"

No existing earthquake catalog provided current, roughly uniform coverage of the map area. Instead, parts of the area are covered by two regional seismograph networks and the Canadian national network, and several states maintain or are compiling their own lists of earthquakes from various sources. Accordingly, making the map required compilation of a catalog. Because this map is designed for the public and not for scientific or engineering use, the map should show each state's earthquakes in a manner consistent with the way that state's authoritative persons or organizations show them. This principle of consistency with authoritative sources in each state was urged by one state geologist within the map area, and it was welcomed by members of other state geological surveys who were contacted during catalog construction. Accordingly, there are two main differences between this catalog and one that would result from a seismologist's research. First, I have not examined the original seismographic or intensity data. Second, the combination of sources used and the relative preference given to each source changed from State to State, and from Canada to the United States. Therefore, the map and its catalog should NOT be used for scientific or engineering purposes, nor to assess seismic hazards or losses. However, the map still shows the relative differences of seismicity between States and large parts of States. The larger damaging earthquakes have been vetted individually by local seismologists.