November 18, 1929 Tsunami: Grand Banks, Newfoundland, Canada

1929, Nov 18, 5:30 pm local time. The earthquake occurred approximately 250 km south of Newfoundland along the southern edge of the Grand Banks. The earthquake triggered a large submarine slump (an estimated volume of 200 cubic km of material was moved on the Laurentian slope) which ruptured 12 transatlantic cables in multiple places, and generated a tsunami... More than 40 local villages in southern Newfoundland were affected, where numerous homes, ships, businesses, livestock and fishing gear were destroyed. Also lost were more than 280,000 pounds of salt cod. Total property losses were estimated at more than $1 million 1929 dollars. (reference #1827)

A tsunami struck the Burin Peninsula of Newfoundland Nov 18, 1929 after the 1702 NST magnitude 7.2 earthquake occurred in the Laurentian Slope Seismic Zone. This event is Canada's most tragic earthquake with twenty-eight lives lost. The tsunami swept into the coast of Newfoundland 2.5 hours after the seismic event near the top of a high spring tide. Water levels first fell far below normal then, in three successive waves, that often arrived on shore as breaking waves, water levels rose 2 to 7 m... St. Lawrence at the head of Great St. Lawrence Harbour was one of the communities inundated, fortunately with no loss of life, but with substantial property damage... The map [St. Lawrence] indicates a tsunami height of about 4 m, a runup height of about 13 m and a runup distance of at least 760 m at the head of the harbour... The earthquake shook loose a portion of the continental slope over a 20,000 km2 area and the resulting turbidity current flowed at 70 km/hr to redistribute 200 km3 of material over a 150,000 km2 area on the Sohm Abyssal Plain… The tsunami created by the Nov 18, 1929 slump on the Laurentian Continental Slope took about 2 hours to reach Bermuda at an average speed of just over 700 km/hr. It took about 2.5 hours to reach the Burin Peninsula of Newfoundland and about 3 hours to reach Cape Breton Island at an average speed of about 144 km/hr... In the case of the 1929 tsunami as it arrived on the Burin Peninsula, in all cases witnesses report it was first seen at about 1930 NST as a major withdrawal (NST is 0.5 hr ahead of AST used in the rest of Atlantic Canada). In the communities of Lamaline, Taylor's Bay, Lord's Cove and Port au Bras there are reports of a breaking wave arriving; up to three main pulses were seen. Many smaller pulses of the tsunami continued to affect the area for several hours after the main event. In Burin Harbour, which is quite deep, the tsunami tended to be seen as a very rapidly rising sealevel over about a 5 to 10 minute period, then the sealevel rapidly fell over the same period... The tsunami with its three successive pulses arrived during a high astronomic tide. To make matters worse, the three main pulses arrived over about a half-hour period near the top of a rising (extra high) 'spring tide' or during "the springes". Fortunately it was a bright moonlit and a windless evening; the sea was dead calm, thus there were no storm waves to do extra damage. In addition, the tsunami's arrival in early evening meant people were up and about and awake to save themselves... Most estimates of the day suggested that the 1929 tsunami elevation was 30 to 50 ft high (9.1 to 15.2 m). In fact, it is doubtful that the tsunami elevation reached more than about 7.5 m above the normal calm sea... (ref #1719)

The 1929 Newfoundland tsunami the tsunami wave heights were 3 m in St. Lawrence Bay and 7 m in Taylor's Bay, but the runup heights at the heads of the bays were about 13 m. (ref #1832)