M8.2 Alaska Peninsula

Forecasted: 2021-06-29

Earthquake occurrence date: 2021-07-29

Depth of earthquake: 43.00 km

*Model was calculated at the date of forecasting

Figure 1: M8.2 Alaska Peninsula; Regional shear-traction field at the time of the earthquake.

Figure 2: M8.2 Alaska Peninsula earthquake – shear-traction field at the near-, intermediate- and far- field distances from the earthquake.

The large M8.2 earthquake on Alaska Peninsula happened during the regional increase of the shear-traction field. The increase was generated by numerous tectonic waves passing over the region.

On 29th June 2021, we forecasted the elevated possibility for earthquakes in the region of Southeast of the Alaska Peninsula for the time period from 25th July 2021 to 31st July 2021. The strongest one happened on 29th July and was followed by several more in the following days.

The earthquake was triggered by a local and regional increase of shear-traction fields in the region. The largest aftershock to the M8.2 mainshock happened during an increase of the near-field effect of the shear-traction.

The M8.2 mainshock happened during the increase in the estimated seismicity rate for the given model. The increase of estimated seismicity rate regarding the long-term seismicity rate was 10-times higher. The probability for such a large magnitude earthquake was 0.64%.