The Office of Civil Defense (OCD) urged the public Sunday, Dec. 22, to be on high alert and take immediate steps to prepare for potential tsunami threats amid a series of earthquakes offshore of Ilocos Sur.

OCD Administrator, Undersecretary Ariel Nepomuceno directed the regional directors of civil defense offices in Ilocos (Region 1), Cagayan Valley (Region 2), and Central Luzon (Region 3) to work closely with partner national government agencies (NGA) and local government units (LGUs) to ensure the safety of residents.

“Check preparations for earthquakes with a possible tsunami resulting from the movement of the Manila Trench,” he said.

From Dec. 17 to 21, the OCD said that the Philippine Institute of Volcanology and Seismology (PHIVOLCS) has recorded 49 earthquakes with magnitudes ranging from M1.8 to M5.0 off Ilocos Sur.

The seismic activity was centered about 100 km west, northwest of Santa Catalina town, and the source of the earthquake events has been attributed to movement near the Manila Trench area, it added.

“Current earthquake activity indicates two likely scenarios: the earthquakes may continue at their current frequency and gradually decrease in the coming days, or they may intensify, resulting in a stronger earthquake that could generate a tsunami,” the OCD pointed out.

The Phivolcs outlined tsunami forecast points, indicating significant risks for nearby areas. It said the projected runup heights include Calayan, Cagayan with a height of 2.5 meters; Pagudpud, Ilocos Norte, expecting 7.6 meters; Laoag City, Ilocos Norte, projected to see 10 meters; Vigan City in Ilocos Sur anticipating 14.7 meters; San Fernando City, La Union at 11 meters; Bolinao, Pangasinan at 11.6 meters; and Palauig, Zambales at 4.8 meters.

The National Disaster Risk Reduction and Management Council (NDRRMC) issued a memorandum directing the OCD in Regions 1, 2 and 3 to undertake specific actions related to local tsunami preparedness. 

The memorandum, signed by Director Cesar Idio, OCD deputy administrator for operations, outlined several key actions for the OCD regional offices, including drafting a tsunami evacuation plan. 

The regional offices shall review the current tsunami contingency plan for each respective region and enhance it by developing a new draft evacuation plan. They must also identify gaps or areas for improvement to ensure alignment with the latest hazard assessments and response protocols. 

“It is crucial to map out evacuation routes that ensure accessibility while prioritizing coastal communities with a 15-minute response time,” the NDRRMC said.

Additionally, the regional offices must validate and map designate evacuation centers for coastal barangays and identify temporary evacuation centers for displaced individuals in the event of massive destruction. Coordination with local government units (LGUs) is essential to strengthen evacuation planning, the NDRRMC noted.

The memorandum also emphasized the necessity of ensuring that tsunami alert and warning systems are operational. This includes testing the functionality of tsunami alert systems to ensure timely dissemination of early warnings and verifying that communication channels with LGUs, communities, and other stakeholders are operational.

The directive also highlighted the need to test the tsunami incident command system which involves conducting drills and simulations to evaluate the effectiveness of the command structure. 

Nepomuceno stressed that if the ongoing tremors west of Ilocos Sur diminish, there remains an opportunity to enhance earthquake preparedness significantly. 

“If our prayers are answered, we still have the chance to double our earthquake preparations —early warning systems, public awareness, drills, inventory of equipment and skilled personnel, and updating of plans,” he said.