Development of a database of historical liquefaction occurrences in the Philippines

Liquefaction is one of the earthquake-related hazards commonly experienced during earthquake occurrences in the Philippines. A database of liquefaction occurrences in the Philippines was developed through the analysis of historical documents, reports, catalogs, newspaper articles, and eyewitness interviews. A total of 808 liquefaction accounts were analyzed—798 of which were induced by 110 earthquakes that occurred from 1619 to 2020, with magnitudes ranging from M 5.1 to 8.3. The database also contains three undated liquefaction accounts from paleoseismic investigations, and seven liquefaction accounts related to four volcanic eruptions. The liquefaction occurrences in the accounts were analyzed in terms of their location quality, liquefaction features, probability ranking, and geomorphic units. We observed that liquefaction can occur repeatedly at the same sites that liquefied during past earthquakes and volcanic activities. This database may be used for seismic hazard studies and disaster risk reduction and mitigation purposes.