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    MALOU    2021-10-25  00:00 UT  18.1N  138.6E   50 kts  West of Central Mariana Is.


TS Malou formed today in the area west of the northern Mariana Islands with winds up to 50 kts. It is expected to track to the north and east over the next week and not to threaten regional seismicity significantly.


A tropical cyclone may be forming west of the central Philippines. This system is currently located at 11N 114E and moving to the west with winds up to 23 kts. It is not likely to greatly enhance regional seismicity at this time.


HURRICANE RICK (17E)        


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HURR  RICK     2021-10-25  00:00 UT  18,2N  102.1E  105 kts  South of Jalisco, Mexico


Hurricane Rick formed south of Guerrero, Mexico today with winds up to 105 kts. It is expected to make landfall in Guerrero near Zihuatanejo and Acapulco, Mexico. Enhanced seismicity is likely in the region of central and western coastal Mexico while this storm is in the area.





October 25, 2021 is the nineteenth 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


Arctic MB>=4.0 30 1.9 0.05

India MB>=4.0 68 2.9 0.02

Hindu Kush MB>=4.0 14 2.0 0.05


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


Mammoth lakes MB>=3.0 -18 -2.1 0.05