Antarctic ice events are readily detectable by distant hydrophones in the Indian Ocean because the sounds propagate well into the SOFAR channel. It may be that the reverse is true. Remote sounds in the ocean from inside and outside the SOFAR channel might also get funneled toward Antarctica as the SOFAR channel nears the surface due to temperature and salinity changes. This would give three active seismic stations on the Antarctic coast T-wave coverage of the Indian Ocean. Based on 7th arc timing, a prominent detection was found on all three stations that may triangulate to a new candidate MH370 location.
Known hydrophones around the Indian Ocean have been closely examined for evidence of an impact or late implosion. Several seismometers have also been examined, mainly looking for seismic P and S wave arrivals. Shoreline seismometers like Amsterdam Island have also been checked for T-wave arrivals, where they are essentially used as hydrophones. The slower sound waves in water are converted into seismic waves at a sloped seabed. Distant Antarctic seismometers were not initially considered, but the advantages of a quiet coastal environment and very shallow SOFAR channel are intriguing.
The three coastal Antarctic seismometers that have a direct SOFAR path are IU.CASY, G,DRV, and AU.MAW, with CASY being closest to the search area. To get the approximate timing, the Oct 2017 CSIRO drift location at 30.5S on the 7th Arc was chosen as the focus of the recent search area. Profiling from there to CASY, MAW, and DRV gave propagation times of 2772, 3220, and 3340 seconds. Adding to the 7th arc timing of 00:19:37 gives target times of 1:05:49, 1:13, and 1:15:17 UTC for expected arrival. Examining the seismic data around those times reveals a prominent arrival on each seismometer:
Distinct signals are seen at 1:10:40 on IU.CASY, 1:18:15 on G.DRV, and 1:21:27 on AU.MAW. Note that the times are later than expected, and the G.DRV arrival is earlier than AU.MAW, which would point to a possible common origin farther northeast. Using these new propagation times with the previously profiled propagation speeds gave new distance estimates. The online geodesic mapping tool at geo.javawa.nl was used to plug those distances in as the radius for a circle centered on each seismometer. Plotting the three circles gave a surprising result. The intersection of each pair was within 50 km of a common location point about 300 km east of the 7th arc. This unfortunately makes it inconsistent with the satellite BTO timing.
Reprofiling the propagation times for the new paths gave a close convergence at a new locus. Allowing for the variation in T-wave conversion of up to 40 km gives a good matchup at 25.938S 104.626E.
T-waves are converted to seismic waves just offshore, typically at a depth of 200m at middle latitudes. The exact depth on the Antarctic coast is unknown, but with the SOFAR channel near the surface, conversion could be very close to the shore. Once converted, the waves travel at faster seismic speeds to the recorder, and polarization analysis would point toward the conversion point. Conversion signals are usually most intense where a broad shelf faces the incoming wavefront. Estimating possible conversion points near these three seismometers appears to reduce the matching error.
The exact impact time is assumed to be within two minutes of the 7th arc timing. The origin locus moves about 1.5 km south on bearing 188.0 for every second after 00:19:37. The locus is moving away from the 7th Arc at supersonic speed, so there would not, for example, be a later match near the saved Shah flight simulator spots. An impact four minutes after 7th arc timing would put the locus at an intersection with the Curtin event bearing around 301 degrees from H01. That impact timing would be compatible with a sustained glide, but still 350 km off from the BTO computations for that time.
Although the matchup is impressively close, the character of the signal arrival at AU.MAW is not typical of a seismic or SOFAR signal. It is a very sharp impulse lasting just seconds. It has an oscillatory decay unlike a recording glitch, but the signal spread would be expected to be much broader, especially in comparison to the very broad CASY signal. Other blips can be seen arriving at around 4 Hz on the CASY trace. These may be typical of distant ice events that arrived through the SOFAR channel. Even if MAW is a local event at the station, the other two arrivals still match up as T-waves at that locus.
Earthquake catalogs give no match for teleseismic events that might account for the arrivals, but an uncataloged event could be responsible.
A Tentative Result
Given the inconsistency with the ping rings and the odd MAW signal character, there is a low confidence that this is the location of the plane, unless there is a major correction to the BTO distance calculations. Still, such a remarkable coincidence should not go unreported. The .kmz file contains more detailed notes on the timing.
Future research prospects are to look for Antarctic T-wave evidence of a late implosion, and to examine the weaker arrivals for timing matches nearer the 7th arc.