| http://www.earthquakesummary.info/ A strong earthquake of M 6.6 hit the region of New Britain, Papua New Guinea today. NEIC reported this earthquake was felt with intensity III in Kimbe, West New Britain and possibly in Australia. No tsunami was expected or observed. This event occurred within a few hours of the full moon tidal event which was complete at 20:14 UT on June 15. This is a subduction zone and the vertical motions associated with this tidal event were probably at least in part responsible for triggering this earthquake. It is likely, however, that another triggering mechanism associated with the strong M 1.3 class solar flare and the geomagnetic storm four days ago also was affective in promoting this event. The epicenter lies about 10 degrees south of the local geomagnetic equator and geomagnetic triggering appears most prominent around four days after geomagnetic storms. The HF map for several hours after this event shows that the strongest HF readings would have been over New Britain about the time of this earthquake. This map and further information on HF systems can be viewed at: http://www.ips.gov.au/HF_Systems/6/5 This is the strongest earthquake in the world since a similar earthquake of M 6.5 occurred late on May 15 about 300 km to the east of today's epicenter coincided with the tidal event associated with the full moon of May 17. As noted in this summary on May 16 "In the past this alignment (full moon) has been associated with strong subduction zone earthquakes". We noted this event related to the previous full moon in out summary yesterday where we stated in this regard: "Recent activity associated with the full moon in these regions included ... an M 6.5 in New Britain on May 15". In particular we identified the regional Solomon Islands as one of two areas where statistics showed a strong increase in seismicity associated with the tidal alignment in our TIDAL section. We also noted that "Baja aftershocks appeared to be enhanced by tidal effects of the full moon alignments". An M 4.1 in Baja occurred several hours prior to the complete alignment today. The geomagnetic effects and the tidal effects added 1.0 units of magnitude to the previously expected maximum magnitude for an event in this region at this time. In particular we had expected an event within about 100 km latitude and longitude of today's New Britain event to occur around June 17 (forecast 60913) with magnitude up to M 6.6. |