Moment tensors provide depth control for reliable tsunami prediction

April 13, 2016

gempa Modules

Seaquakes have the potential to generate destructive tsunamis when the magnitude is large, the earthquake occurs at shallow depth below the ocean floor and the earthquake mechanism has a significant uplift component. Their correct determination is therefore crucial for Tsunami Early Warning conducted in many centres worldwide. False as well as missed warnings may have large societal and economic impacts.

Reliable and unique estimation of magnitude, earthquake depth and mechanism, and the tsunami thread are feasible using SeisComP3 and gempa's TOAST and MTV. The software modules together combine observations of earthquakes and tsunami wave heights with rapid modelling of earthquake soures and tsunami waves.

On 04 April 2016 a shallow M6.8 earthquake struck the Vanuatu region in the open sea. Without the correct determination of the earthquake moment tensor at the centroid depth using MTV the tsunami potential would have been overestimated giving rise to potentially higher tsunami wave heights. Using MTV, the moment tensor and the centroid depth were determined. By inversion for the moment tensor, the initial hypocentre was shifted from tsunami-hazardous depth of just 10 km to a centroid of 33 km. The shift in depth changes the tsunami prediction made by gempa's TOAST from wave heights of about 0.3 m to less than 10 cm at the coasts of the Pacific Islands.

In this way, gempa's TOAST and MTV have contributed to reliable Tsunami-Early warning for the countries of  the Pacific Ocean. Both software modules are applied at data centres worldwide.

TOAST and MTV belong to the gempa product family . MTV is a joint development of gempa and GFZ Potsdam .