Seismic Forecast and Review (May 2017)
Hitting at Least One Nail on the Head
In my last article, I projected that there would be a very good chance (90% above the average) for at least one magnitude 6.7 or greater earthquake to occur somewhere in the world during the last week of April. I named likely places as Japan, followed by a tie between Alaska and Chile. What happened, after a three month period of worldwide seismic activity that was well below average (with one earthquake above 6.7 magnitude when six is the average)? Two earthquakes above 6.7 occurred on the 24th and 28th of April 2017; one was in Chile and then in the Philippines.
In my estimation, this is a sign that for significant seismic events in the world, activity is again on the upswing; as it was from 13 November 2016 to 22 January 2017. To demonstrate the ups and downs of earthquake activity during the past six months, for earthquakes of at least 6.1 magnitude during a 71 day period from 13 November 2016 through 22 January 2017, there were 30 such quakes (representing 37% more than the average of 22 in 71 days). For the next 71 day period, ending on 4 April, there were only 10 such quakes (representing 54.5% less than average). For ten more days, activity remained significantly below average. Since the 15th of April things have been more like average.
The Forecast for May 2017
One reason why things are now looking more average is mostly due to those big quakes on the 24th and 28th of April. They surrounded a peak of angular relationships between solar system bodies which spiked on the 26th of April. If it was not for that, they may not have happened. But 26 April is not the end of the peaks in what I call Astro Aspect-Values (or AAVs). AAVs remain at elevated levels for most of the month of May so I expect it to be pretty busy.
In other words, 24 out of the 31 days in May 2017 will potentially be seismically active for worldwide significant events (all but the 8th through the 11th and the 29th through the 31st of May). Besides the obvious period of 20.5 May through 28 May 2017, when a huge and wide peak occurs, there are potentially very significant dates on the 1st and 2nd of May, the 5th through the 7th of May, and 15.5 May through 20.4 May.
Recent Activity and What It Might Mean for Future Seismic Events
- Pakistan (7 February 2017; magnitude 6.3-6.5)=possible main shock: 7.1-8.0M
- Philippines (10 February 2017; magnitude 6.3-6.5)=ditto: 7.1-8.0M
- Bolivia (21 February 2017; magnitude 6.3-6.5)=ditto: 7.1-8.0M
- Fiji (24 February 2017; magnitude 6.8-6.9)=ditto: 7.6-8.3M
- Kamchatka (29 March 2017; magnitude 6.6-6.7)=ditto: 7.4-8.2M
- Botswana (3 April 2017; magnitude 6.5-6.6)=ditto: 7.3-8.1M (unlikely)
- Chile (24 April 2017; magnitude 6.7-6.9)=ditto: 7.5-8.4M (very possible)
- Philippines (28 April 2017; magnitude 6.8-6.9)=ditto: 7.6-8.4M
Based on my research into foreshocks, a main shock is preceded by a precursory shock approximately one third of the time. However, since some shocks are aftershocks and some are the largest possible for a given area, a follow-up main shock is often not likely. As a result, the chances may be more like 10-15% on average for any given medium to medium-large shock. But, on the other hand, if such a shock should happen in an area that is capable of and has not seen a great quake in a very long time, the chances may be more than 1 in 3 (such as the 6.7-6.9M shock in Chile on 24 April 2017). When such is the case, the foreshock is usually around 0.8-1.5 magnitudes less than the main shock will be. It should be noted that more times than not, a very large earthquake comes without warning. Such may be the case for the location of the next very big earthquake. Although not listed above, Japan and Alaska may be potentially the location of the next very large earthquake. Those two countries, in addition to Chile, were on the top of my list last month and they remain so for this month as well.
© 2017 Joseph Ritrovato