Last March 11, Japan was hit by a magnitude 9.0 earthquake that caused a gigantic tsunami of up to 38.9 meter high, sweeping the coast of the Miyagi prefecture. The earthquake and the succeeding waves struck 15,000 people dead with less than 10,000 still missing.

Aside from loss of life and property, the twin calamities caused several nuclear accidents around the Fukushima Nuclear Power Plant.

Records reveal that the damage could total to more than USD300 billion. The earthquake ranks as one of the top 5 most devastating earthquakes in the world since earthquake records began in the 1900s.

The sight of a live TV coverage of the big waves swallowing concrete communities is astonishing. As Japan tries to recover from the aftermath, more interest grew on how people should deal with earthquakes and tsunamis.

A week after the Japan earthquake, New Zealand was hit by a magnitude 6.5 leaving 65 people dead. Then on March 25, a magnitude 6.8 hit Myanmar killing at least 70 people.

With deadly calamities in close succession, questions are asked if the Philippines could be next, and if it is, how prepared are they for similar catastrophes and what should Filipinos do now as preparation for these.

Are we at risk?

The Philippines’ inclusion in the region called the Pacific Ring of Fire is one reason why the country is at a high risk. The Ring of Fire is home to about 80 percent of the world’s largest earthquakes. The 40,000 km U-shaped basin is marked with oceanic trenches, plate movements, and volcanic belts.

Director of the Philippine Institute of Volcanology and Seismology (PHIVOLCS), Dr. Renato Solidum, points out the areas that can be affected by tsunami in terms of actual inundation based on historical experience: all coastlines on the eastern shoreline fronting the Philippine Sea which borders the Pacific Ocean; to the west, shorelines fronting the South China Sea; and to the south, the coastlines facing the Sulu Sea and the Celebes Sea. Certain islands can also be affected by tsunamis coming from inland seas.

On this hazard map (, one can see that the entire Philippine archipelago is one big tsunami hazard area.

Twin Phenomena

By and large, tsunamis are not well understood due to their rarity. Solidum acknowledged that accurately understanding the basics of the tsunami is the first step to facing such threat.  “Before the Indian Ocean earthquake in 2004, many people had never even heard of the word tsunami and had erroneously tagged them as tidal waves or associated them with storm surges or high coastal waves produced by strong winds during a storm.”

Solidum said, a tsunami is composed of seawater movements generated by shallow-seated earthquakes that produce vertical movements on the ocean floor thus disturbing the water on the surface.

Submarine volcanic eruptions can also produce tsunamis, just as they can be generated from earthquakes that occur as a result of the movement of the trenches near the coast.

As for speed, tsunamis can be very low in the deep ocean, but in there, the speed is 800kph. Near the coastline it slows down at around 40km per hour, but the height can be large depending on certain factors, including the magnitude of the earthquake and the topography of the affected area. Hence, earthquakes are often associated with tsunamis, and should serve as a warning for an incoming tsunami.

Tsunamis have two types: locally generated and distant. Distant tsunamis are seawater movements occurring from earthquakes in other countries in the Pacific such as Japan, U.S. or Chile. The lead-time for such an event would be anywhere between an hour to 24 hours before they are expected to hit the local coast. It’s possible to receive accurate warnings as the speed at which they are traveling is known. This gives time for coastal residents to relocate to safer ground.

On the other hand, locally generated tsunamis can occur from anywhere between 2 to 10 minutes after the earthquake happens. This does not leave much time for official warnings to reach the community at risk, and very often, this means doom for those who are not quick enough to get to higher ground.

The structure of the land directly affects the size of the tsunami as well coastal areas that are flat can expect the waves to reach further inland, as was the case in Japan. Meanwhile, elevated or inclined ground will mitigate the impact of a tsunami wave.

Greater destruction

Looking at a 100-year reference, from the 1900s to the present, we find that the Philippines has endured at least three major events: massive earthquakes ranging from magnitude 9 to 9.5 during the 50s and 60s. In the past 400 years, the Philippines has endured around 40 tsunamis and 90 major earthquakes, a statistic that shows that the more regular typhoons and resulting floods should understandably take more priority.

Nevertheless, their infrequency is compensated by the magnitude of their effects: indeed the tsunami has the potential to be even more devastating than any typhoon we could ever encounter.

Signs of an impending tsunami

The signs of an incoming tsunami are threefold and can be summarized as Shake, Drop and Roll.

The preceding earthquake can either be inland or offshore. But many communities that have experienced the tsunami, for example, the locals of Mindoro who have witnessed the 1994 event, know that immediately after the earthquake they need to go to inland or elevated ground.

People who are still on the coastline may witness a sudden retreat of the waters. This is dangerous as residents may be attracted to exposed sandbars and other interesting sights and approach the beach instead of evacuating the area immediately.  This is distinctly different from slowly receding waters, as in low tides. In some areas, not fronting the moving trench, instead of seeing a drop, they might see a sudden rise of the water level.

The third sign is a sound (a roar) produced by the incoming tsunami as the wall of water pushes the air to produce an unusual sound.

The alarm system

Some coastal areas have bells (batingaw) that should be sounded out to signal the coming of a tsunami. Sirens are good warning signals, but it is better to rely on a system not dependent on electricity or technology.

The Philippines has access to a double warning system. The first is the Pacific Tsunami Warning System which involves countries and territories around the Pacific. Here, information about the earthquake and the possible tsunami is gathered and transmitted to the neighboring countries by the Pacific Tsunami Warning Center based in Hawaii. This data is brought to the Office of Civil Defense, to the media, and eventually down to the beach area.

Phivolcs has its own capability to locate earthquakes worldwide. If all the systems are running, the agency can monitor the arrival of tsunami waves from the different oceans in the world. There are different modalities of warning but one very tested way is through the public broadcasting (radio) media. However, getting this information immediately down to the coastal areas is what needs to be done and what should be improved. Other means of communication not relying on technology should be prioritized in such situations.

Disaster preparedness

Republic Act 10121 also known as the Disaster Risk Reduction and Management (DRRM) Act was passed and approved on May 27, 2010. The act allows for the immediate release of calamity funds to LGUs in order to prepare for disasters. Seventy percent of the total calamity fund can be used for risk-reduction measures and 30 percent for quick response activities. This law should encourage local government units to take initiatives. However, as Dr. Solidum points out, it is one thing to have resources available, and another to take advantage of them.

Phivolcs has presented the steps to be taken to prepare for tsunami-related events. Any disaster-preparedness activity can be participated by at least the barangay captain; if there are no such efforts, then community members can organize among themselves or request their local leadership to organize activities focused on: tsunami preparedness (what should be done before a tsunami arrives) and disaster reduction (what can be done to reduce the resulting damage caused).

Step 1: Increase awareness

The community should not feel that they are faced with the unknown. Basic tsunami information should be properly disseminated.

Step 2: Tsunami hazard and risk mapping

The community must know which areas are at risk. The hazard maps are available on the Phivolcs website and can be downloaded from These maps should be posted in prominent places around the community, properly disseminated and used as a tool to assist emergency responders to plan evacuations.

Step3: Community-based preparedness activities

People should be aware that in some cases tsunamis arrive a few minutes after the earthquake. In such cases, there will not be enough time for the community to receive information or warning from the national government, and must therefore be able to mobilize themselves quickly and follow the routes indicated in the tsunami evacuation map. For this purpose, public signages should be prominently placed, and a detailed tsunami evacuation map based on the tsunami hazard map should be created.

Step 4: Conduct drills

Drills can be conducted in three ways. A tabletop exercise simulates an evacuation drill. The second is a walk through exercise that aims to test how fast people from the coast can reach an identified shelter. People should reach a designated shelter where everyone can gather together so that respondents will not be hard up in locating missing residents. The third is an elaborate drill that should mobilize the entire affected community, including the utilization of various resources and simulating a warning. Another type of tsunami drill involves distant tsunamis and the ability of relaying warnings from the national authorities down to the barangay level.

Some preparations need to be initiated early and sustained over the long term via strong cooperation between residents and NGOs or local government units. Building dikes and mangrove planting (ongoing government projects) and preservation are measures that cannot be done overnight.

How prepared are we?

The GMA News and Public Affairs department released a documentary showing the state of tsunami preparedness in the international community.

According to Angelli Guidaya-Atienza, program manager in charge of the documentary special, Ground Zero, which aired in early May this year, observed that “Based on our own research, there seems to be very little awareness and preparedness on the tsunamis in our country. Before [the earthquake that happened in] Japan, tsunamis are not present in people’s minds”, she said.

Atienza’s team went to several tsunami-hit places in the country including Bicol, Zambales, Mindoro, Leyte and Mindanao. What they found out was an eye-opener. As they simulated tsunami drills, it was interesting to note that only the people from Mindoro and Bicol who are prepared for any impending disaster.

“The Bicolanos are well aware of the dangers. In Albay, the disaster preparedness officer demonstrated how tsunami waves could reach the height of 6 meters. It’s a part of their consciousness,” Atienza observed. “They were serious and orderly in their drills. Given the number of typhoons that pass by the region and their risk to tsunamis, natural disaster is a part of their daily lives so the attitude is different”, she said.

According to the Japan International Cooperation Agency (JICA), the Philippines should prepare for a potential 7.2 earthquake. Metro Manila is a high-risk zone – home to 13 cities and 4 municipalities, it has one of the highest populations in South East Asia. Many earthquake generators or faults including the Valley Fault System (Marikina Valley Fault which stretches from the Anggat Dam in Bulacan to Mt Sungay in Tagaytay), can damage up to 30% of public buildings. A hazard map of the city identifies the presence of brown and red zones where anywhere between 200,000 to 500,000 more houses can collapse. Four red zones in Manila, five in Pasig, one each in Navotas and Taguig, and nine bridges were identified.

“We lack transparency,” Atienza said. “Our scientists are doing their job, monitoring, mapping out the place, but this information is not being accessed by the public. For example there are buildings in the urban areas or the business districts, and based on our findings show that they are on top of a fault. But if you ask the people about this, they don’t know this fact. Will the owner tell you this? In San Francisco (which was included in the documentary), they tell you if the building is on top of a fault, and the landlady herself will give you an emergency kit. It’s a different kind of mindset.”

Chino Gaston, one of the journalists who covered Japan for this documentary, agreed. “Why were the Japanese so resilient in the face of disaster? Because they knew the protocol, they understood the dangers even as children because they go through the drills at school. They knew where to meet up, where to get supplies, the soup kitchens were organized, and they weren’t surprised. Part of the preparation is mental and it should be habit forming.”

We made it clear in the documentary that people should ask for disaster preparedness initiatives from their leaders. If you are not taking measures already, then inform yourselves, find out what needs to be done, and take initiatives. I would encourage that. Though our resources may be limited, we need to give ourselves a fighting chance.” Atienza said.

Dr. Solidum echoed this sentiment. “It’s an event which we can prepare for but we cannot guarantee that everyone can be saved. But at least we have the possibility to prepare,” he said.

First published in the Disasters & Risks section of Volume 1 Issue No.6 of SecurityMatters Magazine – Print Edition