October 3, 1931 Tsunami: San Cristobal Island, Solomon Islands

Reference #414:

1931, October 4, 1931 6:15 [local time]. Validity 4. There was an earthquake on San Cristobal Island. It was apparently incomparably stronger than all other earthquakes in the memory of the European settlers. A tidal wave appeared (in Tuilagi) about 10 minutes after the earthquake on the 4th. At Kira Kira, the rise of water was about 2 m, but since it was ebb tide, the water rose only to the high tide mark, without doing any damage except to one recently built stone moorage, which had already been partly destroyed by the earthquake.

This wave was observed along the entire northern coast of San Cristobal, being somewhat larger in the eastern part of the shore and gradually diminishing to nothing in the direction to the western tip of the island.

At Port Mary (Santa Ana Island), the water retreated a very large distance, and then, after a brief pause, rose quickly and reached the highest high tide mark. This cycle of movements, which required about a minute for its completion, recurred three times with diminishing amplitude. According to depth measurements made after the sea had calmed down, the lowest level reached by the water was about 3.5 m below the lowest low tide mark, so that the total rise and fall of water was about 5.5 m.

Judging by available data, on the south cast of San Cristobal Island, between Cape Surville and Cape Sydney, the water first retreated from shore some distance beyond the lowest low tide mark (it was ebb tide) and then returned and rose, and the water surface became like a wall, which arose at the edge of the reefs. This wall advanced on land like a monolith, carrying away everything in its path. The cycle recurred three times.

The highest level reached was clearly marked on the trees which withstood the onslaught of the water and at most places was about 6 m above the high high tide mark, although at the center of the affected area, whether because the disturbance of the surface of the water nearby was greater, or because of the shore configuration, the level reached was at least 9 m above the high water mark.

Tsunami waves destroyed 18 villages on San Cristobal island; 50 people died (according to other sources 26 people).

Gutenberg, Richter (1954): 3.X; 19h13m13S; 10.5 S,

161.75 E.; M=7.9.

Reference #132:

1931, October 3. Solomon Islands, Christoval. Villages destroyed by earthquake and tidal wave.

Reference #236:

1931, October 3, 19:13. A tsunami from a 7.9 magnitude earthquake on San Cristobal Island in the Solomon Islands region destroyed 18 villages locally and was recorded on the tide gage at Hilo where the water first lowered about 0.07 m, then rose about 0.11 m. At Honolulu the range of

oscillations was 0.05 m.

Reference #237:

1931, October 3,19:13 CMT. A magnitude 7.9 earthquake in the Solomon Islands generated a 9-m tsunami locally and was recorded at Santa Barbara with an amplitude of 1.5 inches, at San Diego with a 1.2 inch amplitude and even smaller amplitudes at the Presidio, Balboa, and La Jolla. Validity 4.