Foreword

Compared to the magnitude 7.8 July 16, 1990 Northern Luzon earthquake, the magnitude 7.1 November 15, 1994 Mindoro earthquake was weaker and less destructive but nonetheless dramatic and can be considered another classic. Both events were tectonic in origin, related to movement along zones of weakness transecting the Philippine Archipelago, the former along the well-known Philippine Fault Zone and the latter along a hitherto unacknowledged active fault which we are now calling as Aglubang River Fault. Like the 1990 event, the 1994 Mindoro earthquake produced geologic features such as fault-related ground rupture and secondary ground failures like liquefaction and landslides though these were minor compared to those brought about by the 1990 Luzon earthquake. In addition, the 1994 event generated a tsunami which accounted for majority of the casualties and wrought significant damage on the northern shoreline communities of Mindoro. Without this tsunami, total casualty would have been only 29 instead of 78.

Luckily, the disaster response machinery of Mindoro province was in place and under the leadership of Governor Rodolfo G. Valencia, response and recovery were prompt, minimizing the toll and losses. National government bodies like the National Disaster Coordinating Council (NDCC), Department of Social Welfare and Development (DSWD) and others, led by President Fidel V. Ramos himself, were also quick and efficient in extending assistance to the affected local government units.

The 1994 Mindoro earthquake reiterated the lessons highlighted by the 1990 Northern Luzon event and provided another opportunity to deepen our understanding of the processes/phenomena generated or triggered by shallow seated and high magnitude earthquakes. Moreover, it underscored the reality of tsunami and the impossibility of issuing timely warning for tsunami of local origin. The time interval between the earthquake and the tsunami hit is too short (2-5 minutes in the case of the Mindoro event) for any meaningful warning system. Other options must therefore be considered to reduce tsunami disaster in the future. One option is to adopt and enforce policies regulating settlements in the areas exposed to tsunami, another is to install mitigation structures, but these must be weighed against the fact that tsunami-generating events are rare and far-between. A less costly alternative is to conduct education and information campaigns to make the concerned inhabitants aware of the hazard, take any strong earthquake as a natural warning for tsunami and immediately flee toward pre-identified places of safety whenever they experience extremely strong ground shaking.

It was precisely this need to develop life-saving reflex action to tsunami which inspired us in early 1994 to organize GHIEA or Geologic Hazards Information and Education Alliance. GHIEA is an alliance of media and science/hazard-oriented government and non-government organizations which aims to promote awareness of and preparedness for geologic hazards. The alliance was finally launched in May 1994 with the following initial member organizations: PHIVOLCS and Science and Technology, Philippine Information Agency (PIA), Office of Civil Defense (OCD), Department of Education Culture and Sports (DECS), Kapisanan ng mga Brodkasters sa Pilipinas (KBP), National union of Journalists in the Philippines (NUJP) and Public Relation Organization of the Philippines (PROP). For the next two years, the alliance will focus its information and education campaigns on tsunami hazard nationwide.

This report was prepared by the PHIVOLCS Quick Response Teams dispatched to document the earthquake and its impacts. We hope it will be useful to everyone and more concerned sectors will joins us in the campaign to promote geologic disaster preparedness and mitigation.

RSPunongbayan
Director