Some seismicity may be affected by weather due to wind, tidal surge and air pressure systems effects of  the continental mass compared with adjoining plate masses. During the tropical storm season in the Northern Hemisphere we keep an eye on tropical storms which may affect seismicity according to our models.  Currently the following tropical storms appear to have potential to affect seismicity in the coming week:





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TS    NYATOH   2021-12-01  00:00 UT  13.8N  136.4E   75 kts  Southern Mariana Islands           


TS Nyatoh (TD 27W) continued today in the area southwest of Guam in the Mariana Islands with winds up to 75 kts. It is expected to track to the north and may enhance seismicity in the area of Guam and the Mariana Islands in the next several days.




The new moon will arrive at 07:43 on December 4, 2021. Longitudes which are at local solar midnight at this time are near 120 West while those at local solar noon are near 60 East. These are the longitude bands most likely to experience tidal triggering effects on seismicity with this new moon. In the west they include much of the western active portions of California, Oregon, Nevada and Washington and in the east, Iran and Afghanistan. A moderate to large earthquake is likely in these areas within the next week from tidal triggering effects. Other areas may also see tidal triggering at this time especially likely near local solar noon and midnight.



December 1, 2021 is the twenty-seventh day after the beginning of the new lunar month. Regions most likely to experience tidal triggering on this day (With associated magnitude ranges; the percent change in seismicity rate over background seismicity rate on this day of the lunar month; statistical z-value and significance level) are:


Region Magnitude range %change z-value Significance level


New Britain MB>=4.0 23 2.3 0.04

Puerto Rico MB>=4.0 28 3.1 0.01

So. California MB>=3.0 59 2.0 0.05

Hindu Kush MB>=4.0 17 2.4 0.04

Utah MB>=2.0 19 1.9 0.05

Aleutians MB>=4.0 35 2.7 0.03


Regions expected to experience reverse triggering (i.e. they are unlikely to experience a significant event at this period of the lunar cycle) are:



Region Magnitude range %change z-value Significance level