Historical Seismograms - Evidence from the AD 2000 Izu Islands ...

STUDIES OF PHILIPPINE HISTORICAL EARTHQUAKESR. G. Valenzuela and L. C. GarciaPhilippine Atmospheric, Geophysical and Astronomical Services AdministrationQuezon City, Philippines1. IntroductionHistorical records from the year 1589 to the present show that the Philippinesfrequently experienced earthquakes of all intensities. This is to be expected sincethe Philippine archipelago lies at the collision junction between the Philippine SeaPlate and the China Sea Plate.A certain degree of development in science and culture was attained by the Filipinoslong before foreign civilizations reached the shores. However, early contactwith Chinese traders did not seem to include any technology transfer on earthquakestudies (the Chinese started seismological studies as early as the 2nd Century B.C.).The earliest record of a Philippine earthquake dates back to 13 July 1589, morethan half a century after the arrival of the Spaniards. The Spaniards built churchesand other civil structures, mostly mortared stone blocks and bricks. In those days,earthquake occurrences and effects were recorded, especially the violent and destructiveones, for the purpose of reporting to authorities for repair requisitions fordamaged structures.In 1865, formal seismological observation and studies were started in the Philippineswith the establishment of the Manila Observatory by the Jesuits. FatherFederico Faura, S.J., was the founder. In the observatory reports of 1865, there wasmention of the construction of a horizontal seismoscope and a vertical seismometer.In a report issued by the Spanish government on an earthquake of 1851, there wasalso mention of a pendulum in operation at a Southern Luzon town.2. Macroseismic DataMany compilations of historical earthquakes are extant, but it was only in 1982that a more concerted effort was made to collect macroseismic data. This was inconjunction with the implementation of the "Earthquake Hazard Mitigation Programin Southeast Asia" under the auspices of the Southeast Asia Association ofSeismology and Earthquake Engineering (SEASEE) in cooperation with the Officeof Foreign Disaster Assistance of the U.S. Agency of International Development(OFDA/USAID) and the U.S. Geological Survey (USGS).The richest source of historical earthquake information was the "Catalogue ofPhilippine Earthquakes, 1589-1899" by Repetti (1946). A group of researchersfrom the Philippine National Library compiled a volume of data, most of whichwere translations from Spanish to English. Materials from American libraries wereobtained from the USGS. Information from newspapers, journals, official and privatecommunications and technical papers also form part of the catalogue sources.A catalogue of Philippine earthquakes in four volumes was subsequently produced.Each volume represents a division of the history of seismological service inthe Philippines.Historical Seismogramsand Earthquakes of the World289Copyright 0 IYXh by Academic Press, Inc.All rights of reproduction in any form reserved.