- Education and Science»
- Geography, Nature & Weather
Seismic Review and Forecast for December 2017
As was suggested in my last forecast of a month ago, the seismic activity for November would look similar to that of September or at least average and less like that of August and October. Those last two months, unlike the others, had no quakes of magnitude 6.8 or larger and significantly less fatalities. For comparison, there were 31 deaths caused by earthquakes in August and one in October, but there were 475 in Mexico in September from the 8.2 and 7.1 magnitude quakes and 483 deaths from the 12 November quake of 7.35 magnitude on the Iran/Iraq border (fatality figures from James Daniell's Earthquake Impact Database).
One difference between the more active months of September and November was that both of the two largest quakes in the earlier month resulted in significant casualties, while in the last month the second largest quake of 7.0 magnitude in the New Caledonia region was harmless. November also produced over twice as many quakes in the 6.4 to 6.7 magnitude range than the average; seven instead of three and compared to four in September. There was also no below average results within five tiers of magnitude beginning with a low of 5.8 and a high of at least 7.1, which has not happened for over at least the past year. The activity of these two months may be a sign that the many months of below average seismicity before them will be contrasted by a long term increase to come.
A recent scientific study also suggested that the next five years will see a worldwide increase in earthquakes of at least 7.0 magnitude due to a slow- down in the spin of the earth on its axis during the last six years. In a recent article I suggested the same thing within the continental United States for earthquakes of at least magnitude 6.6 due to the total solar eclipse of August 2017, the path of which crossed the continental U.S. Looking into the historical record, I have found that the continental U.S. does not seem to follow the trend that this scientific study found (related to the earth's spin) for worldwide earthquakes or, if there is a cause and effect, the start of such an increase is delayed so that when the worldwide seismicity returns to average levels, the frequency in the U.S. then increases for a few years. As a result, the United States may see more than the usual number of large quakes (of at least 6.4 magnitude) during the next eight to ten years.
In this article I will again look at a connection between earthquakes and total solar eclipses, but instead of analyzing the history of such a connection to worldwide eclipses and earthquakes related to the Saros 145 series (the same series as was associated with the August eclipse), three eclipses that reached totality in the western portion of the United States from 1918 to 1979 will be investigated instead.
In the earlier study (related to Saros 145), worldwide earthquakes of at least 7.5 magnitude were found to correlate with the prior eclipses in that series. In this study, since the continental U.S. has a reduced frequency and magnitude range than for the worldwide data set, earthquakes of at least magnitude 6.8 were reviewed. What was found indicated that the average rate of such earthquakes (when Vancouver Island in British Colombia, Canada was included) is one such quake every 4.1 years for a period of 1918 through 1983 or 16 earthquakes in 66 years. Half of those earthquakes occurred within a window of 4.7 years following the three eclipses studied, and six of those eight were within 644 km or 400 miles from the center of the earlier eclipse path.
Although 10 quakes were outside of the range of 644 km (400 miles) from the center of the prior eclipse path, two of those quakes were within 4.7 years following a prior eclipse (with one of those just 50 km outside the 644 km range and the other one inside the distance range of one eclipse but just over 7 years after that eclipse and was also 1.5 days prior to the 29 June 1925 Santa Barbara quake that was 65 km from a separate eclipse path). Based on these three prior total eclipses which were visible in the western portion of the continental U.S., there is an average of two quakes in the U.S. that are within 644 km of the center of the prior eclipse path and less than 4.7 years following it. As a result, based on past indicators, it is expected that there will be at least 137% more quakes than usual during the 4.7 years following the August 2017 solar eclipse, or two to three quakes of a minimum magnitude of 6.8 instead of the usual one for that period of time.
The first and last of the three quakes that were a part of this study happened to pass through the states of Washington and Oregon, or two areas that are concerned with the possibility of a large, damaging and possibly deadly earthquake to occur at some point, possibly in the near future, on the west coast or along the Cascadia Subduction Zone. Both of these eclipses crossed paths near the Mount Saint Helens volcano which erupted in May 1980, or 15 months following the last eclipse in February 1979.
Of the six major quakes that occurred following the three eclipses examined, the largest ones, or the only ones of 7.2 magnitude or larger, occurred off the northern California coast (at the same longitude of 41N07) and related to the same two eclipses. Also of interest is the fact that the two earthquakes which were associated with the last of these two eclipses both had the same tight angular relationship of Mercury near the Sun-Pluto midpoint. This identical aspect comes up on December 4, 2017 at 1415 UT, at the same time as there is a significant spike in Astro-Aspect Values (AAVs) which involves a combination of several angular relationships between solar system objects that have come up often during times of past significant seismic activity. There is also a significant peak in AAVs during 21-25 December 2017 (and a separate, smaller peak from 28-30 December). Also, the aspect that comes into play on December 4, again makes an appearance during the last two days of January and the first two days of February, 2018. There are also peak days worth keeping an eye on for 11, 18, and 22 January 2018.
Although, as usual, the chances of an earthquake of at least magnitude 6.8 occurring during the next two months is greater outside the continental United States than within its borders, the eclipse of August 2017, creates an increased risk within the United States from now through May 2022.
© 2017 Joseph Ritrovato