In 479 BC, when Persian soldiers besieged the Greek city of Potidaea, the tide retreated much farther than usual, leaving a convenient invasion route. But this wasn't a stroke of luck. Before they had crossed halfway, the water returned in a wave higher than anyone had ever seen, drowning the attackers. The Potiidaeans believed they had been saved by the wrath of Poseidon. But what really saved them was likely the same phenomenon that has destroyed countless others: a tsunami. Although tsunamis are commonly known as tidal waves, they're actually unrelated to the tidal activity caused by the gravitational forces of the Sun and Moon. In many ways, tsunamis are just larger versions of regular waves. They have a trough and a crest, and consist not of moving water, but the movement of energy through water. The difference is in where this energy comes from. For normal ocean waves, it comes from wind. Because this only affects the surface, the waves are limited in size and speed. But tsunamis are caused by energy originating underwater, from a volcanic eruption, a submarine landslide, or most commonly, an earthquake on the ocean floor caused when the tectonic plates of the Earth's surface slip, releasing a massive amount of energy into the water. This energy travels up to the surface, displacing water and raising it above the normal sea level, but gravity pulls it back down, which makes the energy ripple outwards horizontally. Thus, the tsunami is born, moving at over 500 miles per hour. When it's far from shore, a tsunami can be barely detectable since it moves through the entire depth of the water. But when it reaches shallow water, something called wave shoaling occurs. Because there is less water to move through, this still massive amount of energy is compressed. The wave's speed slows down, while its height rises to as much as 100 feet. The word tsunami, Japanese for "harbor wave," comes from the fact that it only seems to appear near the coast. If the trough of a tsunami reaches shore first, the water will withdraw farther than normal before the wave hits, which can be misleadingly dangerous. A tsunami will not only drown people near the coast, but level buildings and trees for a mile inland or more, especially in low-lying areas. As if that weren't enough, the water then retreats, dragging with it the newly created debris, and anything, or anyone, unfortunate enough to be caught in its path. The 2004 Indian Ocean tsunami was one of the deadliest natural disasters in history, killing over 200,000 people throughout South Asia. So how can we protect ourselves against this destructive force of nature? People in some areas have attempted to stop tsunamis with sea walls, flood gates, and channels to divert the water. But these are not always effective. In 2011, a tsunami surpassed the flood wall protecting Japan's Fukushima Power Plant, causing a nuclear disaster in addition to claiming over 18,000 lives. Many scientists and policy makers are instead focusing on early detection, monitoring underwater pressure and seismic activity, and establishing global communication networks for quickly distributing alerts. When nature is too powerful to stop, the safest course is to get out of its way.
B.Z. 479'da leşkerê Pers bajarê Potidaea dorpêç kiribûn. Ava deryayê vekêşiya bû, Ew der jî bibû rêya êrişê. Lê bexte wan reş bû, di nîvê rê de, pêlên avê bi ser wan de hatin, hemû xeniqîn. Gelê Potidaea bawer kirin ku Poseidon ew rizgar kirine. Lê tişta ku ew rizgar kirî, ew tişta ku gelekê din jî kuştiya: Tsunamî. Dibejin tsunamî jî Kêş û vekêş e. Lê têkiliya tsunamî û kêş û vekêş tune. Kêş û vekêş bi tevgera roj û heyvê çê dibe. Tsunamî ji pêlên ji rêzê pir mezintir e. Lûtkê û kortên wê hene, ji avê çê nabe, lê tsunamî avê dide ber xwe û dibe. Çavkaniya enerjiya wê cuda ye. Enerjiya pêlê avê, ji bayê tê. Ji bo ku tenê li ser rûyê avê ne, biçûk in. Lê enerjiya tsunamî ji bin avê, ji teqîna agirpija, ji hezaza, û pir cara ji erdhejên bin deryayê tê. Dema bin avê de erdhej diqewime, enerjiyakê pir mezin derdikeve. Ev enerjî avê dide ber xwe û bilind dike, piştre av tê kişindin, pêlên biqasî çiya çê dibin. Wisa tsunamî pêk tê, saetêkê de 800 km rê diçe. Ji bona ku di bin avê re tê, ji dûr naye fem kirin. Lê dema nêzîk dibe tê guhartin. Hindik av li peşî dimîne, enerjiya wê hemû kom dibe. Leza tsunamî kêm dibe, lê bilindahiya wê digihe 300 metrî. Tsunamî di Japonî de tê wateya ''pêlên nêzîk'' ev jî diyar dike ku ji nêzîk xuya dibe. Pêşî kortên tsunamî tên, avê ji keviyê dikişînin. Lewra berî tsunamî, heya însana jê tune. Tsunamî ne tenê mirovên li keviyê dikuje, heta 2 km avahî û dara jî xera dike. Bi taybetî jî herêmên nizm. Wextê av vedikişe jî, dîsa hemû kes û hemû tiştê, li ser rêya xwe wêran dike. Di 2004 li Okyanûsa hindî, felaketekî pir mezina dîrokî qewimî, 200,000 mirov mirin li başûrê Asiayê. Em ê çawa xwe ji feleketê siruştî parezin? Li cih na hewl dan bi dîwarên bilind, deriyê mezin, û bi cokên avê rawestînin. Yek jî bi kêr nehat. 2011 de, li Japonya tsunamî dîwarê parastina Fukushima derbas kir, Di encama felaketê nûkleer de 18,000 însan mirin. Zanyar dixebitin berî ku biqewime, tsunamî fem bikin, û bi tora ragihandinê, hemû kesî şiyar bikin. Dema felaketa siruştî pir bi hêz be, ya herî baş: birevin!