KYUSHU, Japan (CBS) – Scientists say they’ve recorded low frequency shaking on the ocean floor that could be the result of increasing pressure, similar to what was released during the devastating 2011 Japan earthquake and tsunami.
Scientists had previously detected a slow moving underwater shift – or foreshock – along the plate responsible for the 2011 earthquake that sent shock waves around the world and devastated Santa Cruz and Crescent City harbors in California.
In a 2012 article, researchers suggested that such a shift may have caused “substantial stress loading” and unstable conditions that triggered the 9.0 magnitude quake and tsunami blamed for killing more than 15,000 people.
Now a second team of researchers says a similar pattern is emerging in a subduction zone where two tectonic plates are engaged in a “slow” earthquakes that would previously have gone unnoticed.
“Monitoring of offshore seismicity off southern Kyushu, Japan, recorded a complete episode of low-frequency tremor, lasting for 1 month, that was associated with very-low-frequency earthquake activity,” reads the abstract in the journal Science.
These quakes moved in waves along the tectonic ridge and stopped abruptly rather than dissipating slowly and releasing the energy, potentially increasing stress that could be released in a “mega thrust” earthquake, according to IFL science.
The hope is that the discovery of such rumbling in an area where big quakes originate may be a first step in early detection of larger tremors with the potential to cause widespread structural damage and trigger tsunamis.