Tsunami Hill needs more studies–Phivolcs
NOT high enough and too close to the shore.
These are but two of the possible flaws that an expert from the Philippine Institute of Volcanology and Seismology (Phivolcs) pointed out on the planned Tsunami Hill project of the Dagupan City government, to be built in the island barangay of Pugaro.
Joan Salcedo, Phivolcs Science Research Specialist, who came on the invitation of the Sangguniang Panlungsod (SP) told the council last week that based on the scenario that a seven meter-high tsunami will hit Dagupan, a man-made hill of the same height may offer no resistance.
“When we say seven meters high of water will hit Dagupan, this is a seven-meter wall of water. In tsunami, the quake comes from the bottom of the earth and the energy generated from that tremor is transferred to the wall of water moving forward to the seashore,” she explained.
At the same time, Salcedo pointed out that after consulting other experts on the other earthquake-related hazards, such as the Tsunami Hill’s proximity to an existing fault and the shoreline and the liquefaction effect, the devastation in Dagupan during the 1990 earthquake was significantly due to liquefaction.
As to the location of the hill at 300 meters away from the shore, Salcedo said, “Masyado siyang malapit.”
Looking at the scale model of the planned Tsunami Hill, Salcedo pointed to the design of the stairs saying, “I think, it is not good to make the stairs all round.”
She said the plan of the structure must take into consideration how the people will be able to easily climb the top after being warned of the coming of a tsunami.
TSUNAMI THREAT
Salcedo confirmed that the threat of a tsunami hitting Dagupan is possible.
Citing studies made by Phivolcs, she revealed that the source of the tsunami will likely come from the active Manila Trench located less than 100 kilometers off Bolinao.
“If it moves, it can generate an 8.3 magnitude earthquake,” she intoned.
If the Manila Trench shakes, it could spawn a tsunami in Dagupan City with a height reaching as high or higher than seven meters, she added.
She told newsmen after the council session that the frequent tremors being experienced in Mindoro and Negros are associated with the Manila Trench, which extends from the Visayas to the northern part of the archipelago.
When asked by newsmen if there is a possibility that Dagupan could be spared from a tsunami since it lies south of the Lingayen Gulf and covered by the mountains of Labrador, Sual and Bolinao, Salcedo said tsunamis, when they hit, empty into bays and Lingayen Gulf is a bay.
She added that because of the energy packed by a tsunami, triggered by an earthquake, all the structures along the coast will be carried away in its path.
In such a scenario, she said the educational and commercial center of Pangasinan close to the coastline, may likely be flattened to the ground.
COMPREHENSIVE PLAN
Salcedo also stressed that Dagupan should prepare a more comprehensive plan for a tsunami strike, not just the construction of a hill.
“There should be a coordinated and systematic evacuation of the people to a higher ground,” she said.
The plan, she said, must be communicated and understood by all the stakeholders, especially the communities.
Salcedo also urged that plans be made for the post-tsunami scenario as tsunamis hit in single wave but in a series of waves that can last for several hours.
OTHER OPTIONS
Asked by Vice Mayor Belen Fernandez, chair of the SP, if there are other more feasible alternatives to the planned Tsunami Hill project, Salcedo said there should be proper evacuation and a definite evacuation center that is safe.
“We should only resort to vertical evacuation if there is no more evacuation area that can be recommended”, Salcedo said.
The planned Tsunami Hill will cost P9 million, of which at least P4.01 million will be spent for the first phase based on the bidding already conducted and awarded to LM Diaz Trading and Construction by city hall.
The bidding and awarding was undertaken without approval from the SP contrary to standard policy.
The Tsunami Hill was proposed by Mayor Benjamin Lim to supposedly provide a safe haven for residents of the Pugaro island village in case of a tsunami.
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