How tsunamis form and their impacts
On July 30th, at 11:24 AM (Russia's local time), an earthquake occurred near the Kamchatka Peninsula. This was measured to have a magnitude of 8.8, putting it amongst the 10 largest earthquakes in recorded history. The only stronger earthquakes ranged from 9.0 to 9.5, while this earthquake is tied with two other 8.8 magnitudes. At first, economic losses and severe shaking were the main concerns for the mainland, but that quickly turned to the treat of a tsunami. This threat stretched all the way to the states, and has been taking effect over the course of the day.
Tsunamis are caused when an earthquake or volcanic eruption takes place under the sea, with the intensity and length of occurrence both playing factors in the overall strength of the tsunami. The earthquake in this most recent case began to generate a series of waves that then traveled inland area-wide.
As these waves travel inland, they gradually increase in height. This is what causes the shoreline to often recede before the waves reach the mainland. They continue to grow and take on more water before eventually making their way onto shore.
Once they reach the shore, these waves often have strong currents and widespread flooding. There are 3 different types of tsunami alerts depending on the expected impacts of these waves. A watch is issued when a distant tsunami is possible. If this is issued, be ready and prepared to act when new information arrives. An advisory is issued when strong currents and waves are possible/a threat to those in and very near the water. When this is issued, stay out of the water, and stay away from beaches/waterways. A warning is issued when dangerous coastal flooding and powerful currents possible. When this is issued, move to high ground or inland.
Earlier today, a tsunami advisory was put into place for Hawaii and for the some of the coast of California. As these waves moved into areas like Hawaii, waves nearing 6 ft were measured as they hit shore. These advisories have since been dropped as the heights of these waves have decreased and impacts are expected to be overall on the lower end.
