RESUMEN
A 5700-square-kilometer quiet zone occurs in the midst of the locations of more than 4000 earthquakes off the Pacific coast of Nicaragua. The region is indicated by the seismic gap technique to be a likely location for an earthquake of magnitude larger than 7. The quiet zone has existed since at least 1950; the last large earthquake originating from this area occurred in 1898 and was of magnitude 7.5. A rough estimate indicates that the magnitude of an earthquake rupturing the entire quiet zone could be as large as that of the 1898 event. It is not yet possible to forecast a time frame for the occurrence of such an earthquake in the quiet zone.
RESUMEN
A table is presented showing the recorded distribution of the forty-eight species of Anopheles known from the Caribbean Arc. Its primary object is to indicate to Public Health Authorities throughout the Sub-Region with what species dangerous to Health they are threatened by air routes. Certain anomalous distributions of individual species brought out by this tabulation are discussed. Much further detailed Anopheline survey work is obviously called for. Unfortunately most of the areas concerned are under Governments noteworthy for their lack of affluence. A second table is presented showing geological surface changes around the Island arc from the Cretaceous epoch onwards. This is discussed in its bearing upon the distribution of certain species. It is apparent that the spread of some species at least has been across quite considerable stretches of sea, where land bridges have not been available since the last emergence of the Islands concerned(AU)