Matched Filter Detection of the 2018 Fiji Deep Doublet Sequences

Date: 4/26/2019

Time: 06:00 PM

Room: Grand Ballroom

The Tonga-Fiji subduction zone is located in the border of Australian and Pacific plates and contains more than 2/3 of globally recorded deep focus earthquakes (depths larger than 300 km). On August 19^th 2018, a magnitude 8.2 earthquake with depth of 556 km occurred in the Tonga-Fiji region. Two weeks later, another magnitude 7.9 earthquake with depth of 655 km struck nearby area about 250 km southwest to the Mw8.2 Fiji earthquake. The second deep earthquake is likely triggered by the Mw8.2 earthquake, because it occurred in an isolated slab with very low background seismicity and low aftershock productivity. The occurrence of these two earthquakes offers a great opportunity to study the interactions and physical mechanisms of deep earthquakes. However, there are still some missing aftershocks for both earthquakes, likely because their signals are contaminated by mainshock waveforms and coda waves. This could be improved by matched-filter detection. In this study, we perform a systematic detection and relocation to foreshocks and aftershocks associated with this doublet sequence. We used more than 500 aftershocks available in the ISC catalog as templates for detection of 30 days after the Mw8.2 earthquake, and detected more than 1000 and 50 aftershocks for both earthquakes respectively. We plan to extend the detection window longer times before and after the M8.2 and M7.9 earthquakes, and relocate these newly detected events to better illuminate spatio-temporal evolutions of seismicity in this region.

Presenting Author: Chenyu Li

Authors