SGVFD Tsunami Information

Introduction

General information on tsunamis

and specific information

for the Galiano Island area
Delta Map


Basic information on tsunamis

"A tsunami (Japanese for "harbour wave") is series of huge ocean waves caused by a rapid, large-scale disturbance of the sea water. Tsunamis can be caused by submarine volcanic eruptions, submarine landslides, meteor impact, and major earthquakes occuring beneath the seabed causing large vertical movements. In deep water, tsunami waves are less than a metre high, but they can travel at speeds exceeding 800 kilometres per hour and can easily cross an entire ocean basin. When they reach shallow water or narrow inlets the waves slow down and the height can build into a wall of water which causes devastation on the shore."

Source: Natural Resources Canada - Information on tsunamis

Localized tsunami concerns

Delta Map"A strong local earthquake could conceivable cause a landslide at the front of the Fraser River delta, where it slopes into deep waters of the Strait of Georgia. The landslide, if large and sudden enough, might generate a tsunami. The unconsolidated sediments forming the delta front may also fail without a seismic trigger, and yet still produce a tsunami. Landslide-induced tsunamis are particularly dangerous because the waves may locally be very large and the warning time very short. For example, in November 1994 a submarine slide in Taiya Inlet created a wave that reached a height of nine to eleven metres at the shoreline in Skagway, Alaska, causing one fatality and over $20 million of damage. It has long been recognized that the western front of the Fraser delta is at risk from submarine landslides. The Fraser River discharges about 17 million tons of sediment into the Strait of Georgia each year, and much of this sediment accumulates on the steep frontal slope of the delta. Small slides are common in this unconsolidated material, but are shallow-seated and moved down the delta front over a period of hours and consequently did not produce tsunami waves. Researchers have investigated two potential modes of failure at the southwestern delta front. They conclude that a large slide could generate tsunami waves up to 18 m high on the east shores of Galiano and Mayne Island, but that the tidal flats of the delta foreshore would reduce wave energy, and waves at the shoreline in Tsawwassen would likely not exceed two metres, even if they coincided with high tide."

Source: City of Richmond Tsunami Study

Conclusion:

There are no local warning systems in place for a tsunami event. If time provides, a call-out would take place and along with the Provincial Emergency Program and the RCMP, the SGVFD would start an evacuation of effected areas. In a worst case scenario, a tsunami many meters high could reach the eastern shoreline of Galiano Island within minutes of a significant landslide occurring on the south western edge of Fraser River delta. This leaves the SGVFD little or no time to warn the community of an approaching Tsunami. If an earthquake occurs in our area, you should consider immediately leaving the shoreline and heading for higher ground. The fire hall and its' resources appear to be outside the impact area of a local tsunami and would be available to provide assistance after the event.

Further Info:
What Should I Do When I Hear About a Tsunami Warning?
Tsunami Zones for BC
Description of Tsunami Notification Zones for BC



For more information, please contact us by phone at (250) 539-2131 or email us at info@gvfd.ca.


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