Very Dry Start to 2021

16 02 2021

Dale C. S. Destin |

Antiguans have just witnessed the driest start to the year in over a generation. January 2021 was the driest January since 1977 for Antigua, with an island average of 27.4 mm (1.08 in).

Usually January yields 67.3 mm (2.65 in) of rain; however, this time, the total was down by 59%. This puts the rainfall for the month in the well below normal category – the bottom 10 percentile of the most recent climate period – 1991 to 2020.

Such low rainfall is rare for January. How rare? Once in every 27 years, on average, which translates to a 3.7 percent chance of such a low total annually. Usually, there is over a 96 percent chance of the month producing more rainfall.

From a historical standpoint, this is the third driest January on record dating back to 1928. Only January 1977 and 1931 have been drier. January 1931 is the driest on record with 16.3 mm (0.64 in) and January 2006 is the wettest with 2017.7 mm (8.57 in).

Despite the trickle of rainfall for January 2021, the rainfall for the month is usually the most reliable of all months with the lowest variability index of 0.83 or moderate, for the climate period 1991-2020. All other months have a variability index of 1 to 2.37 or moderate to extreme. The variability is obtained by dividing the difference in rainfall of the 90th percentile and the 10th percentile by the median.

Notwithstanding the drier than normal January 2021, the rainfall for January remains without any significant (statistical) trend. The mean rainfall over the past seven climates has not changed significantly, ranging between 65.8 to 79.5 mm (2.59 to 3.13 in), over the period 1928 to 2020.

As we look forward, the rainfall for February is lagging average by about 38 percent, and even if the averaged is reached, there is the high likelihood for rainfall to drop to drought levels by the end of February. About another 35 mm (1.38 in) of rain is needed to stave off drought. This or more rainfall for February 17-28 has only occurred 10 times in the last 55 years – 18 percent of the time.

January is unlikely to be this dry again under the next 27 years. By then, we will be at the middle of the 21st Century – millennials would have reach senior citizen age.

Please continue to follow me for more on what looks likely to be the start of a drought and all things weather and climate via TwitterFacebook and Instagram. Also, share this blog, if you found it useful. 

The Great 1843 Mother of All Caribbean Earthquakes

8 02 2021

Dale C. S. Destin |

At 10:37 am, February 8, 1843 – 178 years ago today, the mother of all Caribbean earthquakes struck the region. This is believed to be strongest of all Caribbean earthquakes, ever reported. Dubbed the “The great 1843 earthquake” by Beauducel and Feuillet of the Institut de Physique du Globe de Paris, it killed more than 1500 people and perhaps up to 6000, most in Guadeloupe, and caused catastrophic damage.  

Earthquake event of 8 February 1843, where black star, southeast of Antigua, indicates epicenter from Feuillard [1985]. Thick dashed lines, with roman numerals between, indicate approximate isoseists – equal earthquake intensity. Dashed areas show the approximate size of the ruptured zones estimated by using the Wells and Coppersmith [1994] relation between rupture length and magnitude. See Natalie Feuillet et al

The powerful earthquake, with an estimated magnitude of 8.5, struck the Caribbean, with epicentre between Antigua and Guadeloupe. Different sources have it centre in slightly different places, which is not unusual; however, all have it within 50 miles of the above-mentioned islands.

The monster quake is credited with the total destruction of the Guadeloupe city of  Pointe-à-Pitre. What the shaking did not demolish directly, fire sparked by it consumed the rest. Eyewitness accounts and newspaper reports painted a very dismal picture of the aftermath of this earth-shattering quake, which caused damage throughout most of the Eastern Caribbean. Here is an account of damage to Antigua, according to an 1843 report by Captain of the ship – Royal Mail Steam Packet Dee, as cited by José Grases G. 1990 and obtained from the The University of the West Indies Seismic Research Centre (UWI-SRC) website:

This island has suffered most severely, the whole of the churches and mills throughout the island being a heap of ruins. The organ in the Church of St. John’s totally destroyed; the Dockyard at  English Harbour is sunk considerably, many parts being under water, the whole of the  stone houses in a complete ruinous state, the walls partly or wholly down; the water tanks containing nearly 11,000 tons of water burst with an  awful crash; the earthquake lasted about 4 minutes. Mr. Hart, Clerk in charge of the Dockyard, English Harbour, states that 3 clocks in the  neighbourhood  stopped  at  10h:  40M:  a.m. Precise accounts had not  been received from the  interior. It is ascertained 40 lives had been lost – fears were entertained it was short of the actual loss. The Governor’s House (Dow’s  Hill) is partially destroyed with nearly all its furniture; the  Ridge Barracks much damaged; the Custom House, Court House, and Wesleyan Meeting House destroyed.”

No photo description available.
Damage from the 1974 Antigua earthquake. The 1843 earthquake was 10 times stronger. Photos by UWI-SRC

This earthquake, which ranks among the top 20 strongest ever in the world, was said to have been felt as far away as New York, USA. It was probably a megathrust earthquake – the most powerful kinds. It was up to 10 times stronger than the infamous 1974 Antigua earthquake and up to 32 times stronger than the 2010 Haiti earthquake.

It must be noted that there are conflicting estimates of the magnitude of this catastrophic event with, at least, one expert indicating that the magnitude was as low as 7.5 to 8. I am more persuaded  by the 8.5 magnitude estimate, since this appears to be the most recent finding – Natalie Feuillet et al., and also supported by, at least, two other experts. In some literature it is listed at magnitude 8.3. At any rate, it was not your garden variety earthquake by any stretch of the imagination.

According to the UWI-SRC, earthquakes are a daily reality across the Caribbean, especially the northeast Caribbean where hundreds occur annually, although most are not felt.

Over the years, the UWI-SRC has expressed concerned over the potential for an 1843 or 1974 caliber earthquake impacting the northeast Caribbean. Although earthquakes, especially large ones, are virtually unpredictable, the public should be prepared, as moderate to significant sized earthquakes may impact the region at any time. Individual, community and national measures should always be in place to mitigate the impacts of earthquakes.

For more on seismic activity in the Eastern Caribbean visit: UWI-SRC. Also please continue to follow me for all things weather and climate via TwitterFacebook and Instagram. Share this blog, if you found it useful.

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