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Updated: 7.9 Earthquake Tonga (Northeast of Australia)

8.1 Earthquake in TONGA

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Scientists discover how an 8.0 Earthquake did not cause a tsunami.

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Now they are saying that there was no tsunami generated after the 8.0 quake in Tonga last May. However, at the time, Reuters did report a small tsuami.

At least the UPI article discusses briefly the mechanics of a tsunami.

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Tsunamis can also be generated by local quakes such as the Papua New Guinea Tsunami in 1998 which struck after a 7.0 earthquake. The New Guinea Tsunami claimed approximately 3000 lives.

Tsunamis are characterized as shallow water waves. Most distance travelling tsunamis break out in the ocean rather than at a shoreline. Damage from most tsunamis is from water swelling up, inundating and washing over the coast line.

• "On July 17, 1998 a Mw = 7.0 earthquake struck the north central coast of Papua New Guinea. Following the earthquake a large tsunami also struck the region. Initial reports claimed that the wave was between 7 and 10 meters and that up to 3000 persons were killed or missing. This seemed to be an unusually damaging tsunami given the size of the earthquake..."

• "Tsunamis are a series of very long waves generated by any rapid, large-scale disturbance of the sea. Most are generated by sea floor displacements from large undersea earthquakes."

• "Tsunamis can cause great destruction and loss of life within minutes on shores near their source, and some tsunamis can cause destruction within hours across an entire ocean basin. Most tsunamis occur in the Pacific region but they are known to happen in every ocean and sea..."
  NOAA Tsunami

• "A tsunami can be generated by ANY disturbance that displaces a large water mass from its equilibrium position. Submarine landslides, which often occur during a large earthquake, can also create a tsunami."
  Tsunami Generation, Propagation, and Inundation

• "What causes a tsunami? "

• "Oceanographers often refer to tsunamis as seismic sea waves as they are usually the result of a sudden rise or fall of a section of the earth's crust under or near the ocean.

• A seismic disturbance can displace the water column, creating a rise or fall in the level of the ocean above. This rise or fall in sea level is the initial formation of a tsunami wave..."

• "...Tsunami waves can also be created by volcanic activity and landslides occurring above or below the sea surface. These types of activity produce tsunamis with much less energy than those produced by submarine faulting.

  The size and energy of these tsunamis dissipates rapidly with increasing distance from the source, thus resulting in more local devastation..."
  Tsunami.org