The phenomenon of a tsunami

Depending on how the earthquake occurs, a tsunami may occur suddenly or upstream. Even if you do not feel the shaking, a distant earthquake may bring a tsunami.

When a huge wave with submarine sediment – a very destructive tsunami – hits the coast – ships, houses, cars, etc. can be instantly swallowed up and even washed up to unexpected heights.

The speed of the tsunami is extremely fast, so if you see a tsunami on the coast, then it may already be too late because you can not run away from the speed of the tsunami.
Moreover, the tsunami will come again and again and the height of the first wave may not be as high as the second wave that follows because it cannot be predicted.

Therefore, whether it is only a slight shaking from a mild earthquake, you should be aware of the possibility of tsunami and evacuate in time.


The mechanism of a tsunami

In an earthquake that occurs at a plate boundary, the top of the land plate is jacked up, causing the seawater directly above to rise and sink – and this movement of the seawater forms a tsunami.

Tsunamis are caused the simultaneous movement of seawater from the sea floor to the sea surface, and the impact and devastation of the massive amount of water that floods coastal areas can be tremendous.

Tsunamis not only occur in the sea but can also occur in the mountains when a large mudslide flows into a lake or pond – or dam, setting off huge waves of water.


The phenomenon of a volcano eruption

The volcano spews out – at hundreds of degrees in temperature – a mixture of ash, pumice, rocks and volcanic gases – called a volcanic debris flow, which pours out at speeds of over a hundred km per hour, burning up all objects in its path. Please evacuate as quickly as possible to a safe place, to avoid being engulfed.

Liquid-like magma, called a lava flow, moves slowly from higher to lower ground and the earth, after the flow passes through, forms a lava earth, which is usually more damaging to solid objects than to people.

The pressure of the magma and the effects of the eruption cause the volcano itself to collapse, instantly burying a large area in sediment. If it flows into the ocean, it is likely to cause a tsunami. Such a situation can only be evacuated before the event.

Special attention should be paid to rainfall after an eruption, as volcanic mudslides are likely to occur. Also, after the immediate volcanic eruption ends, it will in fact continue to erupt for years or decades to come and as it is difficult to recover quickly, it is best to move as far away from the volcano as possible.

Following a volcanic eruption, volcanic ash and other harmful gases fill the air and with the wind, air quality becomes a serious health hazard, so cover your mouth and nose or wear a gas mask and evacuate as soon as possible.

With a snow-covered volcano erupting in winter, beware that as the snow and ice covering the volcanic ash melts, the ash and soil together form a mudslide and it is most important to alert the downstream areas and to stay away from valleys and rivers.

Volcanic eruptions are likely to cause large volcanic earthquakes, and if they occur at the bottom of the sea they may also cause tsunamis.