In 2004, one of the deadliest tsunamis in world history hit the Indian Ocean.
It was a Sunday morning, right after Christmas Day, when a magnitude 9.1 underwater earthquake jolted the Sumatra Coast of Indonesia. The quake spawned tsunamis as high as 30 meters that swept through the shores of countries around the Indian Ocean, such as India, Indonesia, Sri Lanka and Thailand. The huge waves killed over 200,000 people.
This devastating event proves that tsunamis must not be taken lightly. To create awareness about their risks and preventive measures, the United Nations declared November 5 as World Tsunami Awareness Day.
WHAT IS A TSUNAMI?
Tsunami is a Japanese word from “tsu” which means harbor and “nami” which translates to wave. According to the Philippine Institute of Volcanology and Seismology (Phivolcs), a tsunami is a series of waves commonly generated by under-the-sea earthquakes, whose heights can be greater than 5 meters or 16.4 feet.
Tsunamis may occur when an earthquake is shallow-seated and strong enough to displace parts of the seabed and disturb the mass of water over it. They are erroneously called tidal waves and sometimes mistakenly associated with storm surges. Natural signs of approaching tsunami include: a felt earthquake, an unusual sea level change (sudden sea water retreat or rise), and a rumbling sound of approaching waves.
In the Philippines, the 2004 Asian Tsunami greatly impacted the development of early warning signals in coastal communities. In 2012, the Cost-Effective Local Tsunami Early Warning System for Selected High-Risk Coastal Communities of the Philippines was first established in Albay and Pangasinan. The technology is basically made up of a platform with a 15-meter high pole. Two types of sensors are attached to this pole: one that notes the rise and fall of the sea level, and the PHIVOLCS-designed wet and dry sensors. The wet sensor detects post-earthquake receding water which may signal an impending tsunami, while the latter determines if water has already hit the pole.
Information generated by the system reaches local government units (LGU) in near real-time. In cases when an earthquake is strong enough to cause a tsunami, the LGU can sound off the warning siren to warn those living in coastal areas and give them enough time to prepare and flee their homes.
Apart from locally generated tsunamis, distant or far field tsunamis are also being monitored. This happens when an underwater earthquake occurs outside the Philippines or in the Pacific Ocean. Depending on the location, a distant tsunami has a longer lead time as compared to locally generated ones which can only take 2 to 20 minutes before the waves reach the shores of affected areas.
The Philippines is located within the Pacific Ring of Fire, an area in the Pacific border where seismic activities occur, and is also surrounded by bodies of water. This makes us prone to tsunamis.
In December 2007, the Tsunami Hazard Maps were produced under the Department of Science and Technology- Grant-In-Aid Program (DOST-GIA) identifying the following areas that are most vulnerable to tsunamis:
Region I- Ilocos Norte, Ilocos Sur, La Union, Pangasinan
Region II- Batanes, Cagayan, Isabela
Region III – Aurora, Bataan, Zambales
Region IV-A – Batangas, Cavite, Quezon
Region IV-B – Mindoro Island, Palawan
Region V – Albay, Camarines Norte, Camarines Sur, Catanduanes, Sorsogon
Region VI – Aklan, Antique, Guimaras, Iloilo, Negros Occidental
Region VII – Bohol, Negros Oriental, Siquijor
Region VIII – Eastern Samar, Northern Samar, Leyte Island
Region IX – Zamboanga City, Zamboanga del Norte, Zamboanga del Sur, Zamboanga Sibugay
Region X – Camiguin, Lanao del Norte
Region XI – Davao del Sur, Davao Oriental
Region XII – Sarangani, South Cotabato, Sultan Kudarat
Region XIII – Surigao del Norte, Surigao del Sur
ARMM – Basilan, Lanao del Sur, Maguindanao, Sulu, Tawi-Tawi
Because tsunamis can occur anytime of the day, international humanitarian organization Red Cross laid out safety measures before, during and after a tsunami.
– Discuss with your family what to do during a tsunami. This helps reduce fear, particularly among younger children.
– Check your workplace and your children’s schools and daycare centers to learn if they are in a tsunami hazard area or inundation zone. Learn about their evacuation plans, especially the designated spots where you can pick up your children.
– Plan evacuation routes from your home, school, workplace and other places you could be where tsunamis present a risk.
– If possible, try to pick evacuation areas 100 feet above sea level or 2 miles inland.
– If you cannot get that high or far, go as high or far as you can. You should be able to reach the highest ground possible on foot within 15 minutes.
– Practice your evacuation routes. Familiarity may save your life. Be able to follow your escape route at night and during inclement weather.
– Drop, cover, and hold on to protect yourself from the earthquake.
– When the shaking stops, gather members of your household and review your evacuation plan. A tsunami may be coming within minutes.
– Follow instructions issued by local authorities. Recommended evacuation routes may be different from the one you planned, or you may be advised to climb higher.
– Use a battery-powered radio to get updated emergency information.
– If you hear an official tsunami warning or detect signs of a tsunami, evacuate at once. A tsunami warning is issued when authorities are certain that a tsunami threat exists, and there may be little time to get out.
– Take your emergency preparedness kit. Having supplies will make you more comfortable during the evacuation.
– If you evacuate, take your animals with you. If it is not safe for you, it is not safe for them.
– Get to higher ground as far inland as possible. Watching a tsunami from the beach or cliffs could put you in grave danger.
– Avoid fallen power lines and stay away from buildings and bridges from which heavy objects might fall during an aftershock.
– Stay away until local officials tell you it is safe. A tsunami is a series of waves that may continue for hours. Do not assume that after one wave, the danger is over. The next wave may be larger than the first one.
– Let friends and family know you’re safe.
– If you have evacuated, return only when authorities say it is safe to do so.
– Continue listening to local news for updated information and instructions.
– If people around you are injured, practice CHECK, CALL, CARE. Check the scene to be sure it’s safe for you to approach; call for help; and if you are trained, provide first aid to those in need until emergency responders arrive.
Although earthquakes remain unpredictable, tsunamis can now be better foreseen through the use of technology. But this doesn’t give us an excuse to forego preparation. Remember that being prepared for disasters spells the difference between life and death.