Individual Event Report
| Event #527 - Summary, and parameter estimates with source IDs |
| This large and significant earthquake is well known and well represented, both in catalogs and newspapers. The intensity given is for Vancouver, some distance from the epicenter. Higher intensities undoubtedly were felt nearer the epicenter. Earthquake History of the United States summarizes: "Felt in southern British Columbia and northwestern Washington. Buildings shook at Seattle. Magnitude 7.0." The location cited is from the dissertation of Garry Rogers (1983). He says: "Investigations with the set of P arrival times listed in the ISS place the epicentre on Vancouver Island near the west coast, south of the present town of Gold River which did not exist in 1918. Because of the quality of 1918 arrival times this epicentre has an uncertainty of the order of + 50 km. Felt information collected by Dennison (1919) and supplemented by newspaper investigations suggest the magnitude of 7 (Ms) calculated by Gutenberg and Richter (1949) is correct." Earthquake History of the United States says: "Felt in southern British Columbia and northwestern Washington. Buildings shook at Seattle. Magnitude 7.0." |
| TIME |
LOCATION |
MAGNITUDE |
MAX. INTENSITY |
FELT AREA |
| YR |
MO |
DAY |
HR |
MIN |
AM/PM |
Time
Type |
LAT(N) |
LON(W) |
DEP
(km) |
MAG |
Mag
Type |
Felt
Plc. |
Felt
St. |
Inten-
sity |
Int.
Type |
Felt
Area |
Felt
Area
Int. |
Felt
Area
Units |
| 1918 |
12 |
6 |
12 |
45 |
A |
L |
49.50 |
125.90 |
|
7.00 |
G |
Vancouver |
B.C. |
V |
MM |
650000.00 |
|
km2 |
| N-Ore - 1193 |
GCR - 2330 |
- |
MILNE - 1449 |
USEQS - 955 |
GCR - 2330 |
Underlying Source Material
| Source ID |
Publication |
Pub Date |
Pub Details |
| 2330 |
Garry Colin Rogers, Seismotectonics of British Coulmbia, PhD Thesis |
1983 |
PhD Thesis, Dept. of Geophysics and Astronomy, University of British Columbia, pp. 19-27 and p. 228 |
Transcription: TABLE Il
Larger Historic Vancouver Island - Puget Sound Earthquakes
Their Felt Area (In square KM -RSL 6/95) and Resulting Magnitude
FELT PREVIOUS(1) FELT AREA (2)
DATE COORDINATES AREA MAGNITUDE MAGNITUDE
1872 DEC 14 48.6 121.4 1010,000 - 7.3
1903 MAR 14 47.7 122.2 26,000* 4.3 4.9
1904 MAR 17 47.8 123.0 50,000* 6.0 5.3
1909 JAN 11 48.7 122.8 150,000 5.6 6.0
1911 SEP 29 48.8 122.7 8,000 4.3 4.1
1913 DEC 25 47.7 122.5 20,000* 4.3 4.7
1915 AUG 18 48.5 121.4 77,000* 5.5 4.6 (This magnitude is a typographic error in Roger's thesis correct magnitude should be 5.6, based on the felt area given here RSL 6/95)
1918 DEC 06 49.5 125.9 650,000 7.0 7.0
1920 JAN 24 48.6 123.0 70,000 5.0 5.5
1923 FEB 12 49.0 122.7 8,000 4.3 4.1
1926 DEC 04 48.5 123.0 30,000 4.3 5.0
1928 FEB 09 49.0 125.3 120,000 3.7 5.8
(List continues through 1965 - RSL 6/1995)
*Felt area from "Earthquake History of the United States" by Coffman and
von Hake (1973).
1)Magnitude in the Canadian Earthquake Data File.
2)Calculated using Toppozada's (1975) relationships
5) Comments on Revisions of Some Key Earthquakes (Figure 6)
a) March 16, 1904
In the Canadian Earthquake Data File the epicentre for this event was located on the west
side of the Olympic Peninsula and it was assigned a magnitude of 6. in "Earthquake History of
the United States" it is given the location of Victoria, B.C. and assigned an intensity value of V.
A study of felt levels from newspaper reports suggests the earthquake has an epicentre along the
west side of Puget Sound, south of Port Townsend and that the magnitude is about 5. The
confirmation that this earthquake was not near the west coast of the Olympic Peninsula is
important as no large earthquakes have yet been located along the coast.
b) January 11, 1909
Felt reports from newspapers limit this epicentre to the San Juan Islands region where
several instances of damage occurred. Felt information also clearly shows that the size of the
isoseismal maps is between that for the 1965 Seattle earthquake and the 1976 Gulf Islands
earthquake (Figure 7). The magnitude is about 6 according to Toppozada's (1975) felt area
relationship. Lack of aftershocks and lack of higher intensities in the epicentral region suggest
this event belongs to the deeper suite of earthquakes. This event is significant because it
points out that large earthquakes in the deeper suite can also occur north of Puget Sound.
c) December 6, 1918
This earthquake has several epicentres in the literature which are shown in Figure 8.
Investigations with the set of P arrival times listed in the ISS place the epicentre on Vancouver
Island near the west coast, south of the present town of Gold River which did not exist in 1918.
Because of the quality of 1918 arrival times this epicentre has an uncertainty of the order of + 50
km. Felt information collected by Dennison (1919) and supplemented by newspaper
investigations suggest the magnitude of 7 (Ms) calculated by Gutenberg and Richter (1949) is
correct.
d) February 9, 1928
Felt information and a 100 mile distance issued from the Victoria seismograph station (VGZ),
presumably from the S-P interval, indicates the earthquake was in the vicinity of Barkely Sound
and had a magnitude of about 5-3/4. This event was in the Canadian Earthquake Data File but
was located in the Strait of Juan de Fuca with a magnitude of 3.7. It is significant that an
earthquake of this size occurred in the Barkely Sound region as there have been no events
above magnitude 4 in that region since 1928.
e) September 17, 1926 and May 7, 1927
Both of these events were assigned epicentres by the ISS at the location previously
calculated for the epicentre of the December 6, 1918 earthquake (Figure 8). Because of the
proximity of the cities of Nanaimo and Victoria and the distribution of population close to the ISS
epicentral region, these earthquakes could not have been located there as they would have been
felt. With the data listed in the ISS and felt reports they were located elsewhere. The 1927
event occurred in the vicinity of Brooks Peninsula on Vancouver Island and the 1926 event
occurred on the mainland north of Vancouver (see Appendix 1).
APPENDIX 1 - Revised parameters fir earthquakes in the Vancouver Island-Puget Sound Region 1900-1950
( P 128. - Included here are 1900-1928; Times apparently GMT -RSL 5/95)
YEAR DATE TIME LAT LONG MAG
1903 Mar. 14 02:15 47.7 122.2 4.9 Location from "EQ Hist. of the US.", mag. from felt area
1904 Mar. 17 04:21 47.8 123.0 5.3 Location from "EQ Hist. of the US.", mag. from felt area
1909 Jan. 11 23:49 48.7 122.8 6.0 Location based on felt reports, mag. from felt area
1911 Sept. 29 02:39 48.8 122.7 4.1 Location from "EQ Hist. of the US.", mag. from felt area
1913 Dec. 25 14:40 47.7 122.5 4.7 Location from "EQ Hist. of the US.", mag. from felt area
1915 Aug. 18 14:05 48.5 121.4 4.6 Location from "EQ Hist. of the US.", mag. from felt area (Note - the magnitude of 4.6 is due to a typographical error in Table 1 of Roger's thesis. The correct magnitude, based on a felt area of 77,000 square km is 5.6 RSL 6/95)
1918 Dec. 06 08:41:05.8 49.62 125.92 7.0 Recalc. from ISS data. Mag. from Gutenberg and Richter (1949) and felt area.
1919 Oct. 10 01:07:16.5 48.63 127.15 5.5 Recalc. from ISS data. Mag. estimated from the number of P arrivals.
1920 Jan. 24 07:10 48.6 123.0 5.5 Location from "EQ Hist. of the US.", mag. from felt area
1923 Feb. 12 18:30 49.0 122.7 4.1 Location from "EQ Hist. of the US.", mag. from felt area
1926 Sept. 17 23:14:40 50.0 123.0 5.5 Recalc. from ISS data. Mag. estimated from the number of P arrivals. This event was previously identified as occurring on Sept. 7 at 22:14:36
1926 Dec. 4 13:55 48.5 123.0 5.0 Location based on felt reports, Magnitude from felt area
1927 May 7 21:56 50.15 127.85 5.5 Gonzales (VGZ) S-P and felt reports are similar to 1978 Brooks Peninsula events, thus this epicentre is used. Magnitude from felt area. This event was previously identified as occurring on May 8 at 14:00.
1928 Feb. 9 11:05 49.0 125.3 5.8 Location on the basis of Gonzales (VGZ) S-P and felt reports. Magnitude from felt area. |
| |
| Source ID |
Publication |
Pub Date |
Pub Details |
| 1162 |
Townley, S. D. and M. W. Allen, 1939, Descriptive Catalog of Earthquakes of the Pacific Coast of the United States 1769-1928, Chap. III Earthquakes in Washington, 1883-1928, BSSA, V. 29, No. 1, pp. 259-268 |
1939 |
|
| Transcription: 1918 December 6. 12:45 a.m. Northwestern Washington. This shock was severe in Victoria, B. C., and is reported to have been felt as far south as Seattle.-Reid's Scrapbook, 4, 106. |
| |
| Source ID |
Publication |
Pub Date |
Pub Details |
| 955 |
U. S. Dept. of Commerce, 1973, Earthquake History of the United States, V. 41-1, revised ed., pp. 89-96 |
1973 |
|
| Transcription: Dec. 6 00:41* Vancouver, B.C. 49.7 126.5 - V(4) 3-25,43 |
| |
| Source ID |
Publication |
Pub Date |
Pub Details |
| 1193 |
The Oregonian |
1918 |
Friday Dec. 6, 1918, p.1. c.. 3 |
Transcription: VIOLENT TREMOR FELT IN NORTHWEST CITIES
HOUSES SHAKE AND WINDOWS RATTLE AT VICTORIA
Quake Recorded at Vancouver at 12:45 this Morning - Seattle in Path of Disturbance.
Vancouver, B.C., Dec. 6.--Vancouver was violently shaken by an earth tremor at 12:45 this morning. The tremors, which appeared to be from north to south, were felt for two minutes. A distinct rumbling was noticeable. Occupants of tall buildings were especially affected by the disturbance, many being seized with nausea. The shock was felt in all parts of the city, many persons being awakened by the shaking of furniture and tumbling of dishes. In some sections the shock was reported so severe that persons rushed from their beds to the street, fearing that their homes were coming down on them.
Victoria, B.C., Dec. 6.-- A pronounced earthquake of several seconds duration was felt here at 12:45 o'clock this morning. Homes shook and windows rattled all over the city. Island points in the immediate vicinity also reported noticing the disturbance.
Seattle, Dec. 6.--What was believed to be an earthquake was felt in Seattle at 12:45 o'clock this morning. The tremor shook buildings in the downtown district. |
| |
| Source ID |
Publication |
Pub Date |
Pub Details |
| 149 |
Rasmussen, Norman, 1967, Washington state earthquakes 1840 through 1965, BSSA V. 57, No. 3, pp. 463-476 |
1967 |
|
| Transcription: 149 1918 Dec. 6 08:45 49.3 N, 123.0 W V 1 |
| |
| Source ID |
Publication |
Pub Date |
Pub Details |
| 1449 |
Milne, W.G., 1956, Seismic Activity in Canada, west of the 113th meridian 1841-1951: Canada Dominion Obs. Pub., V. 18, No. 7, pp. 119-146 |
1957 |
|
| Transcription: 1918 DECEMBER 6. 00:41 a.m. phi = 49 3/4 degrees N; lambda = 126 1/2 degrees W; M = 7. G. Estevan lighthouse on the west shore of Vancouver Island was the place closest to the epicentre of this earthquake, and considerable mercury was spilled out of the lighthouse lamp due to the tremor. One report stated that the lighthouse itself swayed. At Alberni, 117 miles from the official epicentre, the intensity was rated as IV or V. At both Nanaimo and Ladysmith the earthquake was compared to an explosion. Buildings rocked, and people were violently awakened. The earthquake was felt at Victoria, Vancouver, Kelowna and Seattle, but not at Vernon, Penticton, Chilllwack or Armstrong in the interior. A detailed report was written by F. Napier Denison. Col. |
| |
| Source ID |
Publication |
Pub Date |
Pub Details |
| 1833 |
Woodward Clyde Consultants, unpublished |
1981 |
Woodward-Clyde Consultants (1981), Historical Catalog (1841-1980) for the Pacific Northwest Region, unpublished catalog prepared for the Washington Public Power Supply System. Copy provided to UW in 1993. |
| Transcription: 191812 60841058 49620-125920 V 700N' NO 5 01 |
| |
| Source ID |
Publication |
Pub Date |
Pub Details |
| 323 |
Bradford, Donald C., 1935, Seismic History of the Puget Sound Basin, BSSA, V. 25, No. 2, pp. 138-153 |
1935 |
|
| Transcription: 1918 December 6, 12:45 a.m.; Vancouver, B.C.; felt at Seattle; felt through British Columbia and northwest Washington. |
| |
| Source ID |
Publication |
Pub Date |
Pub Details |
| 1014 |
U. S. Dept. of Commerce, 1973, Earthquake History of the United States, V. 41-1, revised ed., pp. 89-96 |
1973 |
|
| Transcription: 1918. December 6. Vancouver, B.C. Felt in southern British Columbia and northwestern Washington. Buildings shook at Seattle. Magnitude 7.0. |
| |
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