Is there physical evidence that the M8.2 8-Sep-17 earthquake triggered the M7.1 19-Sep-17 earthquake?

The recent large Mexican earthquakes occurred 11 1/2 days and about 600 km apart. The static stress of the first earthquake was not enough to trigger the second (Stein et al., 2017). 11+ days may be too long a time for dynamic triggering to play a role as well. However, Walter et al. (2015) found a link between two M7+ earthquakes that were 9 days and 450km apart in Central America. We use their technique to look for evidence in Mexico. Aftershocks from the second earthquake are used as templates in a match-filter search. In Central America, the technique revealed numerous earthquakes in the location of the second earthquake, but occurring shortly after the first earthquake. In Mexico, the second earthquake only had 11 aftershocks that could be used as templates as there were very few aftershocks (Mexican National Seismological Service - SSN). The match filter search found a total of 21 matches after the M7.1, including the original 11 earthquakes. 1 event occurred 5 days after the M8.2, but there were other events during the month of September before the M8.2. This is very different from the case in Central America where more than 20 events occurred at the site of the second earthquake within 3 hours of the first (Walter et al., 2015). These earthquakes do not give physical evidence of triggering, but perhaps there are smaller earthquakes outside the detection range. We also look for evidence in the GPS signal, but this is complicated by the 2017 Guerrero SSE that started in May. It started earlier than expected, and since it is slip predictable, it was smaller than previous large SSEs in Guerrero. It was ending when the M8.2 occurred, and was reactivated by the M8.2. Thus, GPS signals in southern Mexico contain the post-seismic slip of the M8.2 as well as the SSE. At the time of writing this, there is no clear evidence in the GPS signal of transient slip activated near the M7.1 at the time of the M8.2.