WEATHER PHENOMENA

 

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:

 

TROPICAL CYCLONE HAROLD (25P)

 

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TC    HAROLD   2020-04-04  00:00 UT  14.1S  164.8E  135 kts  Vanuatu     

 

TC Harold formed today in the region of Vanuatu with winds up to 135 kts. It is expected to track to the south and east over the next several days. Seismicity on the area of Vanuatu is likely to be enhanced while ths cyclone is in the region.

 

TROPICAL CYCLONE IRONDRO (24S)

 

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TC    IRONDRO  2020-04-04  00:00 UT  21.5S   78.3E  115 kts  South Indian Ocean          

 

TC Irondro continued today in the South Indian Ocean near Cocos Island with winds up to 115 kts. It is expected to track to the south and east over the next several days. Seismicity on the Indian Ocean mid-ocean ridges is likely to be enhanced while this cyclone is in the region.

TIDAL EFFECTS ON SEISMICITY

 

 

April 4, 2020 is the ninth 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

 

Mt ST. Helens MB>=1.0 55 4.1 0.01

Washington MB>=3.0 19 3.3 0.01

JMA 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

 

East US MB>=1.0 -12 -2.3 0.04