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April 194.0
Extracts fromCatalogue Feltin Guam1825-1938 of Earthquakes W. C. Repetti, S.J. fuIanila Obseruatory The association of earthquakes with oceanic deeps is illustrated by the seismic history of the island of Guam, Marianas Islands. The Nero Deep, to the southeast of Guam, has a depth of 5,269 fathoms at a point about 90 miles from Guam and earthquake shocks can safely be charactefized as frequent in Guam. In the following catalogue we confine ourselves to the shocks which have been perceive,dby persons and reported. The records of the Wiechert Inverted Pendulum seismograph, installed in Agafia in 1914, indicate that there are quite a number of earthquakes which are felt and not reported, or which could be felt under favorable conditions. The reports from Sumay were made by the member of the Co4rmercial Pacific Cable Company who made thelroutine meteorological observations at the point. The reports from Agafla after August 1914, are due to Mr. W. W. Rowley who was in charge of the seismograph from the time of its installation to the time of his retirement in November 1935. Since then the instrument has been under the care of Messrs. Inocencio Aflague and Atanasio Haniu who continue to report the perceptible earthquakes. The fact that most of the earthquakes are reported as felt in Agafia does not imply that they rvere not felt in other places on the island. The sources of information used in the compilation of this catalogue were the following. B,-Diccionario-Geogr6fico-Estadistico-Hist6rico de las Filipinas. Fr. Manuel Buzeta. Madrid. 1850. CA.-Earthquake Records from Agafra, Island of Guam. Cleveland Abbe, Jr. Terrestial Magnetism and Atmospheric Electricity. June 1904, Vol. IX, No. 2. EC.-"El Comercia." A Manila nere'spaper. GM.-"Gaceta de Manila," The official government gazette. the year 1892 Miguel de Lasa of Guam sent to ML.-In Father Miguel Saderra Maso, S.J. a list of earthquakes which he had taken from a manuscript journal of important events in Guam, He ended with the note: "These are the scant data supplied by the above-mentioned book, and they have been verified by persons of that period (1825-70)
who are stiil living, We remind you, however, that the moderate and light earthquakes, which frequently shake us, are not mentioned, but merely the violent ones." -MOB, Sept. 1,902. MOB.-Manila Observatory Bulletins. MOR.-llanila Observatory Records. SM.-Some Notes Concerning the Volcanoes and Seismic Phenomena of the Marianas Islands. Rev. Miguel Saderra Maso, S.J. -MOB. Sept. 1902, VE.-"La Voz Espaflola." A Manila newspaper.
Ti.me-We do not know what standard time was followed in Spanish days; probably mean solar time, corrected at intervals. Our records carty a notation that up to 1916 the time in Guam was th 40- east of Greenwich; and that on August 16th of that year was changed to th 39-. On April 18, 1918 the official time was declared to be that of the meridian 1490 44' 55" east of Greenwich, the meridian of the governor's palace. This involved only a fraction of a second change from the existing standard, too slight to be of any practical importance. On February 7, 1922, the official time was decla;red to be that of the 10th time zone east of Greenlvich, the time of the 150th meridian east of Greenwich. Intensity-In some cases the Rossi-Forel scale of earthquake intensities is referred to. EARTHQUAKES1825 and 1834. During the months of April and lVlay of of the years 1825 and 1834 terrible earthquakes were experience din this island, causing great damage to buildings and spreading consternation among the inhabitants, who believed their last hour had come. 1849. on the 25th of January of this year, ,t t#";ti;* before 3 o'clock in the afternoon, a terrible subterranean noise was heard; at the same instant there was a terrific earthquake, with strong vertical and horizontal movements, lasting a minute and a half, during which time the last fearful hour of complete desolation seemed to have arrived. The tower of the parish church of San Ignacio, that had just been completed, was thrown dolvn upon the roof of the church. The parochial residence of Agafla, as well as those of Umatac, Pago, and Agat, with their churches, and various houses in the towns, were more or less ruined, one of those that suffered most being that of the college of San Juan de Letran. The roof and many timbers fell to the ground, the heavier timbers alone saving it