Human activities can induce earthquakes

AS A MATTER OF FACT - Sara Soliven De Guzman - The Philippine Star

The campaign trail is working doubly hard before next Monday’s election. I hope all our candidates realize how they have turned their towns and cities into garbage damps with all their posters and tarpaulins all over the archipelago. Talk about pollution caused by all these candidates. Are they worthy of winning? They better clean up when all is over and done, lest we see their big faces still posted on the walls, trees, and electric posts after the election.

The citizens need to know that earthquakes can be induced by humans especially by our government officials who do not care about the future. So, before we even vote for our candidates, we must think, think, think. Who amongst our public officials actually care about us? Who protects the environment? There are many officials once elected into office care less about the Philippines. All they care about is how to make money out of their positions in government. Susmariosep!

Many government officials are the culprits to the deterioration of our environment. A study published in the journal Seismological Research Letters a few years ago identified 730 sites where human activity caused earthquakes over the past 150 years. Researchers found out that human activity has induced earthquakes with magnitudes as high as 7.9 – and that the number of earthquakes is clearly rising in some regions of the world. As a matter of fact, these so-called human-induced earthquakes have the potential to be dangerous, even more deadly than the ones caused by nature. Geologists today have begun to understand the repercussions these quakes could have on people and the environment.

What kind of human activity causes earthquakes? According to the report’s data, found on a publicly accessible database, mining accounted for the highest number of human-induced earthquakes worldwide (many earthquakes clustered around 271 sites). The removal of material from the earth can cause instability, leading to sudden collapses that trigger earthquakes. Multiple earthquakes at 167 sites – and by far the deadliest ones – were triggered by what the report calls water reservoir impoundment, or dam building.

In 2008, an estimated 80,000 people died or went missing following a 7.9 earthquake in China’s Sichuan province. Scientists believe it was triggered by the weight of 320 million tons of water that had been collected in the Zipingpu Reservoir – over a well-known fault line.

In the US, the conversation around human-induced earthquakes has largely centered around fracking for oil and natural gas, given the rapid spread of the technology in many states. According to the US Geological Survey, fracking can induce seismic activity, both directly and from disposing of wastewater used in the process. Twenty-nine project sites where found to have earthquakes induced by fracking itself, 36 sites where quakes were induced by post-fracking wastewater disposal, and 12 sites with temblors induced by unspecific oil and gas wastewater disposal.

Earthquake triggers were also identified from nuclear explosions in 22 locations and two construction sites. Miles Wilson, a University of Durham geophysicist who collected the study’s data said that, “All anthropogenic projects influence forces acting in the Earth’s crust. For example, by adding or removing mass, so we shouldn’t be surprised that the Earth responds to these changes and that in some cases earthquakes are the response.”

 “Mining will continue to increase in scale. In fact, today’s mines are bigger than ever and reach miles underground. This activity could lead to more instability in the Earth, and more or larger earthquakes,” Wilson warns.

Aside from the Philippines lying along the Pacific Ring of Fire, which causes the country to have frequent seismic and volcanic activity, we also have environmental problems that may in some ways trigger an earthquake. Mining is one of these.

After the recent magnitude 6.1 earthquake, Rappler Talk spoke to Dr. Mahar Lagmay, UP Resilience Institute Executive Director, on the impact of the earthquake in Pampanga and the factors that led to it. Dr. Lagmay said that the reason why Porac, Floridablanca and San Fernando were the hardest hit was due to the soil condition which was soft (lahar) that amplified the shaking of the ground. From the preliminary analysis of what really happened, there are other compounding factors that are still being studied such as the direction of the movement of the fault and the unconsolidated soil soft sediments that must have amplified the tremors. Were these areas on top a fault line? He said it is not definite but what is sure is that there is a fault line at the epicenter of the earthquake which was in Zambales.

Dr. Lagmay also discussed structural integrity. Was the building constructed according to the requirements of the structural code such as the size of the steel used or the curing of cement? He also pointed out that we have good laws and codes that follow the principles of physics and engineering.

Dr. Lagmay highlighted the importance of knowing what the problem is so that we can solve it in the right way. Earthquake is a phenomenon. People do not die because of the earthquake. People die because of the hazards of the earthquake. He enumerated the four hazards that people need to be aware of: structural integrity of the building, landslide, tsunami and fire. The structural integrity means whether the building followed the building code or not; landslide that is triggered by an earthquake; tsunami is when the earthquake happens offshore and the land under the sea moves (Manila Trench) with a 2-3 kilometers inundation; and fire which usually happens due to gas leaks in the homes or buildings after an earthquake. He gave as an example the earthquake that happened in San Francisco in the 1900’s where many died not because of earthquake but because of the fire. He warned that if the West Marikina Valley Fault moves and brings about the magnitude 7.2 earthquake, widespread fire is feared to happen.

Since we cannot predict when an earthquake will happen, it is very important for us to be aware of how we can mitigate and reduce its impact. Awareness, education and engagement are important factors in reducing the possible loss of lives and damage to property. Awareness is the first step towards disaster preparedness.

Dr. Mahar Lagmay who heads the UP Resilience Institute says that the Philippines is a natural laboratory for hazards. In fact, the world is looking at us on how we react and respond to different calamities and disasters. He reminds us that knowledge is important in order to survive. I hope our government recognizes the importance of science and research so that we can get the right data in localized areas of the country so that we can properly prepare and respond to problems that come our way. More so, I pray that our government officials think country instead of self gain.

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