io6 STEPHEN TABER 



intensity close to IX R.-F., originated about 50 km. north of the 

 coast and opposite the middle of the island; and the shock on 

 September 5, 1908, with slightly lower intensity seems to have had 

 its origin in approximately the same locality. On July 7, 1869, 

 two light shocks were felt on board the ship Esther and Sophie 

 when about 20 km. north of Culebra Island. The earthquake of 

 February 17, 1909, felt over the greater part of Porto Rico and the 

 Virgin Islands, originated along the steep submarine slopes north 

 of Culebra and St. Thomas. On October 29, 1886, an earthquake 

 was felt on board the British brigantine Wilhelmina while over the 

 steep scarp 75 km. north of Anegada Island. 



The north side of the Brownson Trough is entirely under water 

 few soundings have been made in its vicinity, and it is so far from 

 the land that earthquakes originating along its slopes could cause 

 little or no damage; therefore evidence of faulting is not abundant. 

 A broad ridge rising 3,200 to 5,600 m. above the floor of the trough 

 separates it from the North Atlantic Basin. The trough-Hke 

 depression separating Haiti from the Bahama Banks apparently 

 joins the north slope of the Brownson Trough at a slight angle, in 

 much the same way that the Cayman Islands-Sierra Maestra- 

 North Haiti fault zone joins the fault zone on the south side of the 

 Brownson Trough. 



On February 19, 1883, the bark Siddartha experienced a sharp 

 earthquake, lasting 25 seconds, while over the north side of the 

 Brownson Trough in lat. 2o°04'N., long. 67°4i'W. The bark 

 trembled as if dragging over a hard bottom although the depth 

 here is more than 6,000 m. 



On November 29, 1916, and on July 13 and 26, 191 7, severe 

 earthquakes originated in the vicinity of lat. 19° 30' N., long. 

 68° 30' W. The last of these shocks was felt over most of Haiti 

 and Porto Rico and probably had an intensity of IX R.-F. near the 

 epicenter. It was followed by a series of aftershocks lasting several 

 days. These earthquakes of 1916 and 191 7 should be correlated, 

 perhaps, with the trough that separates Haiti from the Bahama 

 Banks for they originated in the area where it joins the Brownson 

 Trough (see page 103). 



