November 4, 1927 Tsunami: S. California, United States

1927, November 4, 13:51 UTC. 34.9 N, 120.7 W, magnitude 7.3 MS, 22 miles northwest of Point Arguello, California. A magnitude 7 earthquake occurred off shore. Six foot waves washed out sections of railroad, and flooded stations at Surf and Pismo. Observed at Avila. Recorded in Hawaii and at Ft. Point and La Jolla. Tectonic source probably but effects also similar to 1878 submarine landslide event. of 10 feet and a very restricted affected area. This tsunami affected about 35 miles of shore line. Validity 4. (reference #237)

The Lompoc earthquake of 4 November 1927 (MS 7.0) was one of the largest offshore events in California, and the associated tsunami was recorded in Hawaii as well as on the California coast. The epicenter of this event has long been debated; one location is offshore where the ocean is about 1000-m deep, whereas another location is very near shore beneath a water depth of less than 100 m... Both the arrival times and waveforms of the recorded tsunami of the 1927 Lompoc earthquake indicate that it occurred offshore at about 34.2oN, 120.75oW, where the water depth is about 1000 m... Using the mechanism solution obtained by them, the seismic moment is estimated to be 3 X 1026 dyne-cm, corresponding to Mw = 7.0. This value is consistent with the surface-wave magnitude, indicating that tsunami excitation is similar to that expected from surface waves. The large tsunami observed at Hilo is due to the bathymetric effects near Hilo Bay. The tsunami magnitude estimate of 7.6 made by Abe (1979) is apparently an overestimate because of this effect. (reference #3796)

1927, November 4, 5:51. There was a strong earthquake with source on the edge of the shelf on the northern boundary of the Murray - fault zone. Large slides took place on the coast in the Santa Barbara district, and the movement of traffic on the railway was interrupted. Flues were damaged at Lompoc and other coastal settlements. A very strong seaquake was felt on the "Sokonia" 50 km (27 miles) from Arguello Point, on the "Alaska Standard", 25 km (15 miles) from the same cape and on other vessels.

A tsunami arose, which was observed on the coast of California and was registered on the Hawaiian Islands. An employee from Surf reported that there was a wave 'approximately 1 1/2 - 2 m (6 feet) high, which began with the crest. A railway employee at Port San Luis observed a fall and rise in water level of 1 1/2 m (5 feet) followed by oscillations in level for an hour. According to the lighthouse attendant, in the same port a rise occurred, followed by a drop of 11/4 m (4 feet), without subsequent substantial oscillations. An observer at Pismo Beach compared the tsunami with large storm waves.

The tsunami was registered by the tide gauges at Cape Fort (San Francisco), at San Diego and at La Jolla. On the first record, the oscillations began with a slow drop in level at 7:00, with a half period of 24 minutes. Then more rapid oscillations began with a period of about 15 minutes and a maximal amplitude of 4 cm. The sign of the first onset of the tsunami of the record at La Jolla is not definite. The oscillations had a period of 15 minutes, a maximal amplitude of 6 m and lasted about 13 hours.

At Hilo (Hawaiian Islands), the tsunami began 5.1 hours (at 8:33) after ebb tide, the maximal amplitude of oscillations was 10 cm, the period 12 minutes. At Honolulu, the tide gauge registered weak oscillations with an amplitude of 2 cm and a period of 20 minutes.

(above from reference #415)