Natural disasters result in huge socio-economic losses and tsunamis are no exception. When tsunamis occur and flood coastal zones, they may have a wide range of catastrophic effects on both the natural and built environments. Effects on the natural environment include the complete reorganisation of coastal systems as well as negative impacts on natural ecosystems and resources. Whilst such impacts on the natural environment may seem of no importance, it will be shown that in fact, such impacts can have significant economic and social implications for areas dependent on particular natural resource bases, i.e., by destroying the assets of a country’s tourist industry. With respect to the built environment, tsunamis may have a range of direct economic effects which include loss of infrastructure, utilities, trade and other economic activity and social effects that include death, increased unemployment, disease, and even in extreme cases, civil unrest and riot.

Tsunamis are rare phenomena and their action is both short-lived and violent. Tsunamis may be locally generated and affect coastlines close to their point of origin. Less frequently, large tsunamis may be generated that propagate across entire ocean basins ( and are called teletsunamis), causing huge destruction and economic loss simultaneously at diverse and distant locations. In order to gain an understanding of the effects a large tsunami may have, it is of value to examine the economic and social impacts associated with such events. Remarkably, to the author’s knowledge, no studies have been undertaken which systematically describe and document the socio-economic impacts of any tsunami. This may be a reflection of the fact that the destructive tsunamis that have occurred in recent years have affected areas which are not significantly developed and which do not have large portfolio’s of insured assets (e.g., Indonesia, Nicaragua and Papua New Guinea).

This study attempts to overcome this difficulty by examining some of the socio-economic impacts of the March 27 1964 Alaska earthquake-tsunami event. The data presented have been collated from a large number of sources that make coincidential observations of the socio-economic impacts but which were not concerned with these aspects specifically. The locally generated tsunamis associated with the March 27 1964 earthquake were enormously damaging and their impacts were felt, in some cases, for many years. Whilst the areas of Alaska which were impacted in 1964 were not significantly developed, post-1964 development of the infrastructure and economy of the region means that if there were a repeat of the 1964 earthquake-tsunami today, substantial socio-economic losses would be incurred.

This report begins by providing a summary of the tectonic setting of the Alaska region and a short review of the recent earthquake and tsunami history of the area. The report then provides a summary of the State of Alaska’s socio-economic structure and characteristics prior to the impact of the 1964 earthquake-tsunami. The document then describes the impacts and effects of the earthquake-tsunami and provides information for various settlements that were affected. The report then considers the potential impacts of a 1964 magnitude event if it were to occur in 1999-2000. To this end, the report firstly provides a review of the State of Alaska’s socio-economic structure in 1999-2000 and then attempts to quantify the potential impact of a 1964 earthquake-tsunami. From this analysis it will be seen that the potential impact of such an earthquake-tsunami would be catastrophic and could have a significant global macro-economic effect for particular economic and industrial sectors.

Alaska has three physiographic divisions: the Rocky Mountain system to the north, the Intermontane Plateau in the interior and the Pacific Mountain system to the south that includes the coastal zone. The Pacific Mountain system includes the Aleutian Island Arc, the Alaska Peninsula and the Alaska Range west of the "Panhandle". The arc system is defined by an oceanic trench (the Aleutian Trench), numerous volcanic islands and an active zone of earthquakes. The arc is divided in to approximately 12 separate tectonic blocks and major earthquakes are related to the boundaries of these blocks. Each block is about 350 to 700 km long and the recurrence interval for large magnitude earthquakes is about 100 to 200+ years. Teletsunamis generated by earthquakes occurring along these tectonic blocks radiate perpendicular to the arc and therefore, tsunamis generated in the western Aleutian Islands are likely to effect Japan and the western Pacific. Those from the central parts will effect Hawaii most strongly and those generated in the eastern end of the arc will effect the coast of western North America.

Southern Alaska and the adjoining Aleutian Island chain together constitute one of the most seismically active zones of the world. Approximately 7% of the annual release of seismic energy occurs within this region. Between 1899 and 1965, seven earthquakes were recorded with a Richter magnitude of 8 or larger and over 60 earthquakes were recorded with a Richter magnitude of 7 or larger. Significant changes in ground elevation (uplift and subsidence), as well as horizontal ground movements were associated with many of these earthquake events. Enormous vertical movements of the sea floor associated with earthquakes within the shelf area of the Gulf of Alaska have generated large tsunamis which have propagated across the Pacific Ocean (e.g., the 1946 and 1964 teletsunamis). In addition to the major teletsunamis that are generated in this area, many damaging local tsunamis have originated within the narrow steep sided fjords that characterise much of the coastline of southern Alaska. Many of these local tsunamis are generated along the Fairweather Fault system. The Fairweather is a major tectonic feature of the southern Alaska region and is much like the San Andreas system in California. Whilst the type of movement along this fault system (horizontal rather than vertical) means that tsunamis are not really generated as a direct result of earthquake activity; earthquakes on this system do cause large underwater sediment slumps at the heads of river deltas entering the sea. These sediment slumps in turn trigger tsunamis. Tsunamis have also been generated by a variety of processes associated with erupting volcanoes in the region.

Alaska has a complex tsunami history and it is highly probable that the tsunami history of the area is incomplete because of factors such as low population density and a short written record. The shores of Alaska have been impacted by both locally generated tsunamis and by those that have propagated to the State’s shores from outside the region. Landslide generated tsunamis triggered by earthquakes are common in the Prince William Sound and southeastern Alaskan areas. Such tsunamis are considered unique in the world because of their frequency and magnitude. For the period 1737 to 1996, 96 tsunami are reported to have affected the shores of Alaska (see Table 1).

ORIGIN DATA TSUNAMI DATA

Date Cause Run-up (m) Comments

16/10/1737 Earthquake 12-15 Driftwood deposited by the tsunami
06/08/1788 Earthquake up to 88 Many villagers drowned
1853/1854 Landslide 120 Many drowned
06/10/1883 Volcano 9.1 Houses flooded and ships grounded
04/07/1905 Landslide 35 Erosion of land surface
27/10/1936 Landslide 150 50 barrels of salmon destroyed
10/07/1958 Earthquake/landslide 525 10 km² of forest washed away
28/03/1964 Earthquake/Landslides 67.1 US$311 million damage