By Jade Zaldivar
THE tsunami alert level 2 that was issued after a magnitude 8.9 quake hit Japan has caused a stir not only among residents of 19 provinces identified by the National Disaster Risk Reduction Management Council but also in Davao City where thousands of residents within coastal areas evacuated and moved to higher ground. Some even went up the Shrine Hills. Others proceeded to the City Hall in their panic.
Moving to calm the nerves of her panicky constituents, Davao City Mayor Sara Duterte-Carpio directed Central 911 and other emergency response units to stand by for action. She later told Edge Davao that Central 911 is well- equipped and always ready. Following the tsunami within the Pacific Region caused by 8.9 magnitude earthquake in Japan March 10, some residents in the city panicked.
Mayor Sara said employees of the City Social Services and Development Office and the Davao City Disaster Coordinating Council sprang into action rushing to the coastal areas in the evening of March 10 and saw to it that the people were given whatever assistance they needed.
“(The) employees explained to the people that they do not need to go to the Shrine and the City Hall. We also facilitated the ferrying of people back to their homes,” Duterte said.
The city’s chief executive explained that earthquakes and tsunamis are “natural disasters that are difficult to predict precisely when and where they will happen.”
“Out Central 911 is equipped to respond to disasters, but is limited by its capacity and available resources,” the mayor said. She said the local disaster council is regularly updated by the national office. “Our disaster coordinating councils are in regular communication with barangay officials on status updates, when to evacuate, where to go and what to do,” she said.
“People should also coordinate with their barangay officials so as not to create unnecessary panic,” she added.
Alert level 2 only advises the public to be “on alert for unusual waves.”
“Based on tsunami wave models and early tide gauge records of the tsunami in the Pacific, coastal areas in Philippine provinces fronting the Pacific Ocean are expected to experience wave heights of at most one meter. The first tsunami waves will arrive between 5 p.m. to 7 p.m., March 11, 2011 (Philippine time) and may not always be the largest. These waves may continue for hours,” the National Disaster Risk Reduction and Management Council (NDRRMC) stated in its bulletin.
Davao City, which is shielded from the Pacific Ocean by the Davao Oriental peninsula, did not allow residents to be unconcerned as the Davao City Disaster Coordinating Council through Central 911 chief Colonel Verner Monsanto ordered coastal barangays to be on alert for unusual wave activities.
“While it (tsunami alert) will directly affect Davao del Sur and Davao Oriental, it might slightly affect some of our coastal barangays,” Monsanto said. “The council has requested coastal barangay captains to conduct coast watching. We are closely monitoring,” the bulletin added.
Philippine Institute of Volcanology and Seismology (Phivolcs) Director Renato Solidum raised tsunami alert level 2 on all provinces facing the Pacific Ocean just over an hour after the earthquake in Japan and shortly after the tsunami that followed.
These provinces include Batanes, Cagayan, Ilocos Norte, Isabela, Quezon, Aurora, Camarines Norte, Camarines Sur, Albay, Catanduanes, Sorsogon, Northern Samar, Eastern Samar, Leyte, Southern Leyte, Surigao del Norte, Surigao del Sur, Davao Oriental, and Davao del Sur.
On Friday, small tsunami waves struck the country in early evening, but caused no damage or casualties.
Like Japan, the Philippines lies in the Pacific “Ring of Fire.” Scientists cite studies that show that a large number of buildings in Manila would be damaged or destroyed by a similar 8.9-magnitude that hit Japan.
Aside from the Philippines, other areas in the world that were placed under a lower tsunami watch were the Marshall Islands, Indonesia, Papua New Guinea, Nauru, Guam, Micronesia and Hawaii.
The magnitude-8.9 earthquake struck Japan off its northeastern coast 2:46 p.m. Friday (1:46 p.m. in the Philippines), triggering a 13-foot (four-meter) tsunami that washed away cars and tore away buildings along the coast near the epicenter.
A once-exotic word that has now entered the everyday lexicon, a tsunami refers to a shock of water that spreads through the sea, usually after a sub-sea floor quake.
A section of seabed is thrust up or driven down by violent movement of the Earth’s crust.
The rift displaces vast quantities of water that move as waves, able to cover enormous distances over open water, sometimes at the speed of a jet plane.
An 8.9-magnitude quake off Japan’s northern coast on Friday generated a 10-meter tsunami that picked up ships and dashed them into coastal towns. Buildings and vehicles were carried away as the huge wall of water swept inland.
The word “tsunami” comes from the Japanese words for “harbor” and “wave.”
At their point of generation, tsunamis have a relatively small wave height, with peaks far apart.
As the waves approach the shore they are compressed by the shelving of the sea floor, reducing the distance between the peaks and vastly increasing the height.
To those on the shore, the first sign of something amiss can be the retreat of the sea, which is followed by the arrival of large waves.
“The sea was driven back, and its waters flowed away to such an extent that the deep seabed was laid bare and many kinds of sea creatures could be seen,” wrote Roman historian Ammianus Marcellus, awed at a tsunami that struck the then-thriving port of Alexandria in 365 AD.
“Huge masses of water flowed back when least expected, and now overwhelmed and killed many thousands of people… Some great ships were hurled by the fury of the waves onto the rooftops, and others were thrown up to 3 kilometers from the shore.”
Several factors determine the height and destructiveness of a tsunami.
They include the size of the quake, the volume of displaced water, the topography of the sea floor as the waves race to the coast and whether there are natural obstacles that dampen the shock.
Destruction of protective mangroves and coral reefs and the building of homes or hotels on exposed beaches are fingered as leading causes of high death tolls from tsunamis.
Large quakes are the main drivers of tsunamis, but the phenomenon can also be sparked by other cataclysmic events, such as volcanic eruptions and even landslides.
In 1883, a volcano shattered the Pacific island of Krakatoa, causing a blast so loud that it could be heard 4,500 km away, followed by a tsunami that killed some 30,000 people.
The tsunami of December 2004 in the Indian Ocean was caused by a monstrous 9.1-magnitude earthquake off the Indonesian island of Sumatra.
It released energy equivalent to 23,000 of the atomic bombs dropped on Hiroshima, according to the US Geological Survey. Some 220,000 people in 11 nations were killed, many of them thousands of kilometers from the epicenter.
On Aug. 17, 1976, a 7.9-magnitude earthquake in Mindanao spawned a tsunami that affected more than 700 km of coastline around the Moro Gulf in the North Celebes Sea—the largest tsunami-inducing quake to have occurred in Mindanao, according to the Philippine Institute of Volcanology and Seismology.
Nearly 5,000 died while some 10,000 were injured in the Mindanao quake and tsunami, according to Phivolcs. The World Almanac put the Mindanao death toll at 8,000. More than 2,000 went missing.
The Pacific Ocean is particularly prone to earthquakes and therefore to tsunamis.
But research has found that, over the millennia, tsunamis have occurred in many parts of the world, including the Atlantic and Mediterranean. A global monitoring network, overseen by the United Nations, has been set in place to alert areas at risk.
