ALASKA TSUNAMI SCENARIO (Source: US Geological Survey) September 4, 2013 Walter Hays, Global Alliance for Disaster Reduction, Vienna, Virginia, USA

The Science Applications for Risk Reduction Tsunami Scenario Stephanie Ross and Lucile Jones, Editors

The tsunami scenario team began work on the scenario before the magnitude-9.0 earthquake/tsunami that struck Japan in March 2011

SCHEMATIC OF TSUNAMI WAVE (USGS)

SCENARIO CONCLUSIONS In the scenario, a tsunami generated by a massive earthquake off the coast of Alaska would leave the northern Orange County coast and Long Beach underwater. Source: U.S. Geological Survey report, Wednesday (Sept. 4, 2013).

SCENARIO CONCLUSIONS The simulated tsunami disaster follows a M9.1 earthquake in Alaska would force the evacuation of about 750,000 Californians and damage or sink one-third of the boats in California marinas.

COLLISION OF BOATS IN A MARINA (March, 2011)

SCENARIO CONCLUSIONS The twin ports of Los Angeles and Long Beach could be shuttered for at least two days because of strong currents, potentially losing $1.2 billion in business.

SCENARIO CONCLUSIONS The hypothetical simulated disaster would force the evacuation of about 750,000 Californians and damage or sink one-third of the boats in marinas statewide.

TIME TO GET OUT OF HARM’S WAY: Under the scenario, it would take about four hours for tsunami waves to reach communities near the Oregon state line and about six hours to reach San Diego

ESTIMATED ECONOMIC LOSSES: AT LEAST $8 BILLION

BACKGROUND

BOOK OF BOOK OF KNOWLEDGE - Perspectives KNOWLEDGE - Perspectives On Science, Policy, On Science, Policy, And Change And Change

REGIONAL DEFORMATION EARTHQUAKE TSUNAMI VIBRATION FAULT RUPTURE FOUNDATION FAILURE AMPLIFICATIONLIQUEFACTION LANDSLIDEAFTERSHOCKSSEICHE DAMAGE/LOSS DAMAGE/ LOSS DAMAGE/LOSS

Basic Tsunami Mechanism  An earthquake causes a vertical movement of the seafloor, which displaces the sea water.  Large waves then radiate from the epicenter in all directions.

TSUNAMIS OCCUR IN PACIFIC “RING OF FIRE,” INDIAN OCEAN, CARIBBEAN, AND MEDITERRANEAN

TSUNAMIS GENERATE WAVES THAT CAN AFFECT DISTANT SHORELINES THOUSANDS OF MILES FROM THE SOURCE

TSUNAMI WAVE APPEARANCE A tsunami wave crest has three general appearances from shore: –Fast-rising tide –Cresting wave –A step-like change in the water level that advances rapidly (called a bore) Series of waves –Most tsunamis come in a series of waves that may last several hours –The outflow of water back to the sea between waves can cause more damage than the incoming wave fronts –The first wave is rarely the largest A bore on the Qian Tang Jiang River, China Source:

PERSPECTIVES ON WHAT CAN BE DONE TO BECOME TSUNAMI DISASTER RESILIENT Coastal planners are having meetings this week around the state to digest the scenario information and review their evacuation plans.

Tsunami Risk Reduction The least expensive and the most important mitigation effort is … "Even without a warning system, even in places where they didn't feel the earthquake, if people had simply understood that when you see the water go down, when you hear a rumble from the coast, you don't go down to investigate, you grab your babies and run for your life, many lives would have been saved." Lori Dengler, Humboldt State University New Scientist Magazine January 15, 2005

LOSS REDUCTION MEASURES TSUNAMI WARNING/ SYSTEM DISASTER SCENARIOS EVACUATIONS TSUNAMI WARNING/ SYSTEM DISASTER SCENARIOS EVACUATIONS

The power of knowledge: Victor Desosa saved the village of Galbokka in Sri Lanka in 1994 because he knew what to do when the water receded. Only one inhabitant in his village was killed. Casualty rates in nearby villages were 70 – 90 %

LOSS REDUCTION MEASURES PROTECTION (BUILD INFRA- STRUCTURE TO WITHSTAND) LAND-USE CONTROL (COMMUNITY PLANS) PROTECTION (BUILD INFRA- STRUCTURE TO WITHSTAND) LAND-USE CONTROL (COMMUNITY PLANS)