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I don't understand how such a big explosion caused such a minor Tsunami. My understanding is that the waves that hit the coasts weren't causing much major damag

I don't understand how such a big explosion caused such a minor Tsunami. My understanding is that the waves that hit the coasts weren't causing much major damage? I really held my breath the hours after the explosion.

kzrdude 5y ago
The size of the explosion doesn't really scale with it - it's the size of moved earth that determines the power in the tsunami. So the power of the landslide or moving seabed, if I understand correctly. See also the description of the generation of the 2004 tsunami: https://en.wikipedia.org/wiki/2004_Indian_Ocean_earthquake_and_tsunami#Tsunami https://en.wikipedia.org/wiki/2004_Indian_Ocean_earthquake_a...
shagie 5y ago
From what I understand, it has to do with the volume of the water that is displaced. With a tsunami caused by a fault it can be massive. For example, the 2014 Indian Ocean ( https://en.wikipedia.org/wiki/2004_Indian_Ocean_earthquake_and_tsunami#Tectonic_plates https://en.wikipedia.org/wiki/2004_Indian_Ocean_earthquake_a... ) > An estimated 1,600 km (1,000 mi) of fault surface slipped (or ruptured) about 15 m (50 ft) along the subduction zone where the Indian Plate slides (or subducts) under the overriding Burma Plate. The slip did not happen instantaneously but took place in two phases over several minutes: Seismographic and acoustic data indicate that the first phase involved a rupture about 400 km (250 mi) long and 100 km (60 mi) wide, 30 km (19 mi) beneath the sea bed—the largest rupture ever known to have been caused by an earthquake. For the Tonga eruption - https://www.npr.org/2022/01/18/1073800454/nasa-scientists-estimate-tonga-blast-at-10-megatons https://www.npr.org/2022/01/18/1073800454/nasa-scientists-es... - that's 1.5x smaller. Furthermore, that energy released wasn't all in the ocean, some of it went into the atmosphere. Another example for https://en.wikipedia.org/wiki/2011_Tōhoku_earthquake_and_tsunami https://en.wikipedia.org/wiki/2011_Tōhoku_earthquake_and_tsu... > An upthrust of 6 to 8 metres (20 to 26 ft) along a 180 kilometres (110 mi) wide seabed at 60 kilometres (37 mi) offshore from the east coast of Tōhoku resulted in a major tsunami that brought destruction along the Pacific coastline of Japan's northern islands. From an energy released perspective, the 2004 earthquake: > The energy released on the Earth's surface (ME, which is the seismic potential for damage) by the 2004 Indian Ocean earthquake was estimated at 1.1×1017 joules (110 PJ; 26 Mt). This energy is equivalent to over 1,500 times that of the Hiroshima atomic bomb, but less than that of Tsar Bomba, the largest nuclear weapon ever detonated. Another measure is that that was a 9.1-9.3 magnitude quake. The 2011 quake and tsunami was a 9.0-9.1 magnitude quake. Tonga was estimated to have a surface-wave magnitude of 5.8.

kzrdude 5y ago

The size of the explosion doesn't really scale with it - it's the size of moved earth that determines the power in the tsunami. So the power of the landslide or moving seabed, if I understand correctly. See also the description of the generation of the 2004 tsunami: https://en.wikipedia.org/wiki/2004_Indian_Ocean_earthquake_and_tsunami#Tsunami https://en.wikipedia.org/wiki/2004_Indian_Ocean_earthquake_a...

shagie 5y ago

From what I understand, it has to do with the volume of the water that is displaced. With a tsunami caused by a fault it can be massive. For example, the 2014 Indian Ocean ( https://en.wikipedia.org/wiki/2004_Indian_Ocean_earthquake_and_tsunami#Tectonic_plates https://en.wikipedia.org/wiki/2004_Indian_Ocean_earthquake_a... ) > An estimated 1,600 km (1,000 mi) of fault surface slipped (or ruptured) about 15 m (50 ft) along the subduction zone where the Indian Plate slides (or subducts) under the overriding Burma Plate. The slip did not happen instantaneously but took place in two phases over several minutes: Seismographic and acoustic data indicate that the first phase involved a rupture about 400 km (250 mi) long and 100 km (60 mi) wide, 30 km (19 mi) beneath the sea bed—the largest rupture ever known to have been caused by an earthquake. For the Tonga eruption - https://www.npr.org/2022/01/18/1073800454/nasa-scientists-estimate-tonga-blast-at-10-megatons https://www.npr.org/2022/01/18/1073800454/nasa-scientists-es... - that's 1.5x smaller. Furthermore, that energy released wasn't all in the ocean, some of it went into the atmosphere. Another example for https://en.wikipedia.org/wiki/2011_Tōhoku_earthquake_and_tsunami https://en.wikipedia.org/wiki/2011_Tōhoku_earthquake_and_tsu... > An upthrust of 6 to 8 metres (20 to 26 ft) along a 180 kilometres (110 mi) wide seabed at 60 kilometres (37 mi) offshore from the east coast of Tōhoku resulted in a major tsunami that brought destruction along the Pacific coastline of Japan's northern islands. From an energy released perspective, the 2004 earthquake: > The energy released on the Earth's surface (ME, which is the seismic potential for damage) by the 2004 Indian Ocean earthquake was estimated at 1.1×1017 joules (110 PJ; 26 Mt). This energy is equivalent to over 1,500 times that of the Hiroshima atomic bomb, but less than that of Tsar Bomba, the largest nuclear weapon ever detonated. Another measure is that that was a 9.1-9.3 magnitude quake. The 2011 quake and tsunami was a 9.0-9.1 magnitude quake. Tonga was estimated to have a surface-wave magnitude of 5.8.