Spatio-temporal evolution of low-magnitude seismicity before the May 24, 2013, Sea of Okhotsk earthquake recovered by waveform cross correlation. Is it an earthquake prediction case?

Abstract

According to the International Data Centre (IDC), the Sea of Okhotsk earthquake occurred at 05:44:49.7 on May 24, 2013, had coordinates 54.89°N,153.31°E, mb=6.27, and depth of 604 km. The USGS moment magnitude is 8.3. The previous event detected by the IDC in the surrounding volume 53°N-57°N, 151°E-155°E, depth from 400 to 700 km occurred on February 6, 2012. Using the same seismic data from the stations of the International Monitoring System together with detection and phase association methods based on waveform cross correlation, a series of low-magnitude earthquakes was recovered immediately before this major earthquake. More than 200 events obeying the Event Definition Criteria adapted by the IDC were found between May 13 and the mainshock, with a sudden increase in their occurrence rate starting on the afternoon May 19. The evolution of the numbers of these low-magnitude earthquakes in various ranges of statistical significance within the source volume demonstrates some features, which can be related to the approaching initiation of the Sea of Okhotsk earthquake.

It was found that the results are significantly biased by the effect of side-sensitivity of the WCC detector to the high seismicity at regional distance from the studied volume. There was a M6 earthquake on July 19, 2013. The effect was studied after this paper had been published and revealed the bias. Okhotsk Sea earthquake occurred on May 24, 2013. This case is currently under investigation