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 BERGUITTA (06S)
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TC BERGUITTA 2018-01-16 00:00 UT 18.2S 061.9E 124 kts South Indian Ocean
Tropical cyclone Berguitta (06S) continued in the south Indian Ocean today with winds up to 125 kts. This system is expected to track over La Reunion Islands over the next several days. A volcanic episode and/or seismicity on the Mid-Indian Ridge is possible as the storm moves through the area. The antipode at 18N 118W is off the western coast of Mexico near the tip of the Gulf of California and is not expected to see much promoted seismicity from this weak storm at this time but could become more importance around January 18 when the Gulf of California is antipodal to this storm.
TIDAL EFFECTS ON SEISMICITY
The new moon will arrive at 02:17 UT on January 17. Longitudes experiencing maximum tidal stress at this time are near 35W and 145E longitudes. These are similar to those of the new moon of January 2 which arrived at 02:24 UT. The same areas are likely to experience maximum stress with the new moon. These were noted in previous issues as:
"The full moon will arrive on January 2, 2018 at 02:24 UT. This is a supermoon with the moon at its closest point in its orbit. Tidal effects are likely to be about 30% larger than with a normal full moon. Longitudes experiencing maximum tidal stresses at this time center about 20 degrees around 37W and 143E and include the mid-Atlantic and the east Pacific rim including New Guinea north to Honshu, Japan. These are most likely to see a strong tidally triggered earthquake in the next six days but tidal triggering is possible in many areas and is not limited to these longitudes." (January 2, 2018)
January 16, 2018 is the twenty-ninth day after the beginning of the 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
Alaska MB>=4.0 6 2.0 0.05
Aleutians MB>=4.0 40 3.1 0.01
New Britain MB>=4.0 25 2.6 0.03
So. California MB>=3.0 67 2.3 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: