Numerical modelling and evacuation strategies for tsunami awareness: lessons from the 2012 Haida Gwaii Tsunami

Figures & data

Figure 1. Tsunami vertical sign that indicates entering a hazard zone. (Photo taken by the third author at the California coast on 2013 May 13).

Figure 2. Location of the tide gauge stations, as presented in table 1, and the epicentre.

Table 1. Tide gauge stations data considered in this study.

Station No.	Location	Latitude (ºN)	Longitude (ºW)	Arrival time (UTC)	Time of maximum water level (UTC)	Maximum water level (m)
1	Sand Point, AK	55.3	160.5	6:48	8:14	0.06
2	Kodiak Island, AK	57.7	152.5	6:01	6:01	0.14
3	Seward, AK	60.1	149.4	6:00	—	0.16
4	Yakutat, AK	59.5	139.7	5:22	11:35	0.15
5	Elfin Cove, AK	58.2	136.3	4:34	4:48	0.07
6	Sitka, AK	57.1	135.3	4:26	5:58	0.10
7	Port Alexander, AK	56.2N	134.6W	4:10	6:02	0.11
8	Winter harbour, BC	50.7N	128.3W	4:01	5:50	0.22
9	Neah bay, WA	48.4N	124.6W	5:03	6:38	0.11
10	Port Angeles, WA	48.1N	123.4W	5:50	6:40	0.12
11	La Push, WA	47.5N	124.4W	4:48	7:57	0.12
12	Westport, WA	46.9N	124.1W	5:13	5:21	0.08
13	Garibaldi, OR	45.6N	123.9W	5:12	5:19	0.05
14	South beach, OR	44.6N	124.0W	5:28	5:28	0.09
15	Charleston, OR	43.3	124.3	5:23	7:32	0.13
16	Port Orford, OR	42.7	124.5	5:21	8:41	0.23
17	Crescent city, CA	41.7	124.2	5:44	9:14	0.44
18	Arena Cove, CA	38.9	123.7	6:01	6:37	0.35
19	San Francisco, CA	37.8	122.5	6:52	8:02	0.14
20	Port San Luis, CA	35.2	120.8	6:36	8:10	0.27
21	Hanalei, HI	22.2N	159.5W	8:29	8:54	0.19
22	Nawiliwili, HI	22	159.4	8:51	—	0.03
23	Haleiwa, HI	21.6N	158.1W	8:30	8:57	0.43
24	Mokuloe, HI	21.4N	157.8W	8:34	8:57	0.09
25	Honolulu, HI	21.3	157.9	8:44	9:09	0.20
26	Makapuu, HI	21.3N	157.7W	9:34	9:35	0.27
27	Kahului, HI	20.9	156.5	8:37	9:07	0.79
28	Kawaihae, HI	20	155.8	8:42	9:34	0.56
29	Hilo, HI	19.7	155.1	8:37	10:11	0.29
30	DART 46410	57.6N	143.8W	4:28	—	0.03
31	DART 46409	55.3N	148.5W	5:44	—	0.02
32	DART 46403	52.7N	156.9W	5:28	—	0.02
33	DART 46402	51.1N	164.0W	6:09	—	0.02
34	DART 46419	48.8N	129.6W	3:44	—	0.07
35	DART 46404	45.9N	128.8W	4:17	—	0.05
36	DART 46407	42.6N	128.9W	4:56	—	0.07

Figure 3. The seismo-tectonics of the Queen Charlotte fault: (a) Location of the Queen Charlotte Fault and plate boundaries; (b) aftershocks of the October 28 earthquake.

Figure 4. Historic seismicity off-shore Canada and the epicentre of the October 28 earthquake: (a) magnitude; (b) focal depth.

Figure 5. Tsunami numerical model results: (a) sea surface displacement, in metres; (b) tsunami travel times; (c) maximum water level.

Table 2. Comparison between observed and modelled travel times.

Station No.	Location	Observed travel time (min)	Modelled travel time (min)	Difference (model – obs.)
1	Sand Point, AK	224	239	15
2	Kodiak Island, AK	177	178	1
3	Seward, AK	176	187	11
4	Yakutat, AK	138	122	–16
5	Elfin Cove, AK	90	104	14
6	Sitka, AK	82	106	24
7	Port Alexander, AK	66	67	1
8	Winter harbour, BC	57	44	–13
9	Neah bay, WA	119	108	–11
10	Port Angeles, WA	166	150	–16
11	La Push, WA	104	104	0
12	Westport, WA	129	129	0
13	Garibaldi, OR	128	129	1
14	South beach, OR	144	137	–7
15	Charleston, OR	139	140	1
16	Port Orford, OR	137	131	–6
17	Crescent city, CA	160	155	–5
18	Arena Cove, CA	177	173	–4
19	San Francisco, CA	228	223	–5
20	Port San Luis, CA	234	234	0
21	Hanalei, HI	325	327	2
22	Nawiliwili, HI	347	321	–26
23	Haleiwa, HI	326	322	–4
24	Mokuloe, HI	330	330	0
25	Honolulu, HI	340	335	–5
26	Makapuu, HI	326	326	0
27	Kahului, HI	333	326	–7
28	Kawaihae, HI	338	347	9
29	Hilo, HI	333	322	–11
30	DART 46410	84	88	4
31	DART 46409	100	97	–3
32	DART 46403	144	142	–2
33	DART 46402	185	182	–3
34	DART 46419	40	39	–1
35	DART 46404	73	72	–1
36	DART 46407	112	106	–6

Figure 6. Tsunami numerical model results: tsunami water level waveforms.

Figure 7. Hawaii Islands and the places described by the witnesses during the evacuation: (a) main islands; (b) Kauai; (c) Oahu; (d) Molokai; (e) Maui; (f) Hawaii (Big Island).

Table 3. Timeline of the evacuation process at Hawaii.

Time (UTC)	Actions taken
3:04	The PTWC announces a magnitude Mw 7.1 earthquake had hit Haida Gwaii in British Columbia, Canada, but no tsunami was generated and no action was needed.
3:21	Information only to the state of Hawaii: Pacific-wide destructive tsunami is not expected and there is no tsunami threat to Hawaii.
3:45	Information only to the state of Hawaii: Based on all available data there is no destructive tsunami threat to Hawaii. However, some coastal areas in Hawaii could experience small non-destructive sea level changes and strong or unusual currents lasting up to several hours. The estimated time such effects might begin is: 10:28 pm HST, Saturday October 27, 2012 (8:28 UTC, Sunday October 28, 2012).
5:09	First tsunami warning was issued for the state of Hawaii by the PTWC.
6:00	Tsunami sirens began blaring across the island, prompting a mass exodus of more than 100,000 people that blocked roadways as motorists fled low-lying areas. Tsunami sirens initially failed to work in Keaukaha, Waiakea and in some areas of Puna (East Hawaii, figure 6(f)) but the problem was rapidly solved (SAAP 2012).
6:36	Maui Civil Defence Agency also issued a tsunami warning and an immediate evacuation advisory for all persons in low-lying coastal areas, ordering to evacuate immediately to higher ground. Water and sewer services were closed in preparation for the tsunami. Heavy traffic was reported in South Maui (figure 6(e)) at the Ohukai/South Kihei Road intersection (figure 7), through Lahaina Town in both Front Street and Honoapiilani Highway in town (figure 4(a)).
7:00	Kahului Airport, Maui Island (figures 6(e) and 7(c)) still had three incoming flights planned. Other flights were standing for clearance. Hotels had evacuation plans in place and clearance was given to all hotel guests in a high rise, above the fourth floor. All persons outside the evacuation areas were advised to stay off the roads and highways and refrain from sightseeing (Osher 2012). At the Hilo International Airport, vehicles lined up in an orderly fashion in order to evacuate Keaukaha (figure 6(f)) (Corrigan 2012).
7:09	The Department of Education opened the Maui High School gymnasium (figure 6(b)) as an evacuation centre. Maui Police Department sent units to evacuate beaches and other low-lying areas.
7:30	All roads in the tsunami zone were closed, except for emergency vehicles.
7:40	Lahainaluna High School gymnasium (figure 7(b)), Molokai High (figure 6(d)) and Community Centre parking lots were also available for use as well.
8:10	The Maui Research and Technology Park (figure 7(a)) was opened as a waiting area for the public.
8:17	The King Kaumualli Elementary School holding area, in Kauai Island (figure 6(b)), was reported full and people in the Lihue and Hanamaulu areas were directed to the Wilcox Elementary School (Scheuring & Meiers 2012).
8:28	The counties of Maui, Hawaii Island, Kauai and Oahu reported either little or no damage from the tsunami waves, but there were four serious car accidents in Oahu, and in Molokai, there was some damage to property near the ocean (Zimmerman 2012).
	Tsunami waves did begin to hit Hawaii every 10–12 min, but they were just about 45 cm in height. In Maui, waves reached as high as 1.35 m in Kahului.
9:00	Smooth evacuation on Front Street in West Maui (figure 4(a)). Surges were reported in the East Maui area of Hana (figure 1(e)).
10:22	All water and wastewater services were restored to all areas though the tsunami warning was still in effect.
11:02	The PTWC downgraded the warning to a tsunami advisory, allowing people to return to their homes in low-lying areas 30 min later.
11:26	Maui County Civil Defence authorities said that based on all available data, the tsunami threat had decreased and was then at the advisory level and not expected to increase. Sea-level changes and strong currents might still occur along all coasts that could be a hazard to swimmers and boaters as well as to persons near the shore at beaches and in harbours and marinas. The threat might continue for several hours. Beaches would be closed until the advisory was cancelled (Osher 2012).
13:58	The tsunami advisory for the state of Hawaii was cancelled.

Figure 8. Evacuation details at Maui Island (figure 6(e)), showing the streets where heavy traffic was reported, the tsunami inundation areas, and the location of the evacuation areas. (a) South Kihei; (b) Lahaina; (c) Kahului.

[SAAP] Star Advisor staff and The Associated Press. 2012. Advisory lifted, officials ‘grateful’ tsunami wasn't worse [Internet]. [cited 2013 Feb 25]. Available from: http://www.staradvertiser.com/news/breaking/176136301.html?id=176136301

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