Tsunami is one of the great disasters that can damage infrastructure, ecosystems, and lives. People who live on the coastal area should be aware of how long after an earthquake is a tsunami. It is important because they should evacuate as soon as possible after the signs appear.
There are two types of tsunamis, such as delayed tsunamis and immediate tsunamis. This category divides them according to the speed of travel to the coastline. However, they do not have other factors, such as the severity and distance. Read the overview about both tsunamis here.
How Long After An Earthquake Is A Tsunami in an Immediate Tsunami
Overview
An immediate tsunami is the wave that arrives on the coastline shortly after the earthquake. It can be because of the magnitude and the distance of the epicenter to the coastline. The destruction level of this tsunami is very serious. People only have a little time to evacuate.
The biggest factor of an immediate tsunami is the earthquake with >7.5 on the Richter scale. The seafloor might have displacement. A major displacement would cause powerful waves on the surface. The speed can be more than 500 mph, so the critical time is very short.
Proximity to The Coastline
If the epicenter is close to the coastline, the wave arrives quickly to the shore. Other factors such as depth and the shifts on the ocean floor also contribute to the length of the critical time. How long after an earthquake is a tsunami? Usually, the tsunami will arrive in 5-15 minutes on the coastline.
Tsunami Characteristic
There will be two main waves as the tsunamis in this immediate tsunami. The first wave is the largest one and it won’t be in a single wave. The series would have an interval, probably in hours. It also can be a small wave as the sign of the next one will be bigger.
The second wave of tsunami in the immediate tsunami is the most tragic tsunami. The height of the wave is up to 30 meters. It depends on the magnitude of the earthquake itself. The bigger the magnitude, the higher the tsunami. The topography of the coast will influence how the waves break.
The Danger in Immediate Tsunami
An immediate tsunami is highly dangerous because people barely have time to evacuate themselves. This is such a high emergency for the authorities to note. So, they have to prepare a reliable early warning system to tell people to stay away from the coastline when the sensors read this potential.
How Long After An Earthquake Is A Tsunami in a Delayed Tsunami
Overview
A delayed tsunami is the wave that arrives on the coastline a few hours after the triggering event. The factor is the distance of the epicenter to the coastline, that is far or the depth is great. The tsunami will travel to the coastline and it gradually weakens.
However, this tsunami is still a dangerous one because people are not aware of the triggering event. Warning of a tsunami can be issued suddenly without an earthquake experience. It may create confusion among people and they do not take the warning seriously.
Proximity to The Coastline
The tsunami travels slowly to the shore and it takes about hours. For example, the epicenter can be in the middle of the ocean. To reach the shore nearby, it takes about three hours. However, the speed can be more than 500 mph as the immediate tsunami.
Tsunami Characteristic
The wave can be massive and strong. The series of the wave is a single wave. However, the height of the tsunami will not be as high as an immediate tsunami. The wave is gradually weakened because of the distance of the travel.
The Danger in Immediate Tsunami
Though the destruction may not be as severe as the immediate tsunami, flooding on the coastline is very possible. The massive wave is going to sweep the whole coastline area. However, people have much time to avoid as long as the early warning system works properly.
Since how long after an earthquake is a tsunami will be different, the government should put a lot of concern into preparing an early warning system. The vital device is an SMS broadcaster to send the warning message to many people. Read more about the function and features of the device here.
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