tectonics: tsunami risk management

Tsunami Risk Management

Tsunami Generation

• Tsunamigenesis• Most generated at

subduction/convergent boundaries

• Most active is the Japan – Taiwan boundary

• Not all earthquakes generate tsunami, mostly over 6.5 richter

• Can also be from volcanic collapse or landslides

Impacts

• Two case studies boxing day tsunami

• Stromboli – 2002 and others

2004 Tsunami

Banda Aceh

Sri Lanka

Kalutara Beach

Drawback

Inundation by the wave

Detection

• Un-noticeable in open water – why?

• Wave length 150 to 250km

• Drawback before landfall

• Pacific Warning system

Famous Tsunamis• December 26, 2004: A massive

earthquake off the coast of Sumatra generates tsunami waves that wreck coastlines in 10 countries, killing more than 280,000 people.

• August 16, 1976: A tsunami hits the Moro Gulf region of the Philippines, killing 5,000 people.

• March 28, 1964: The Good Friday earthquake in Alaska creates a tsunami that envelopes the Alaskan coastline. The same tsunami also hits Oregon and California. A total of 132 people die.

• June 15, 1896: The 70-foot-high Sanriku tsunami strikes Japan, killing 26,000 people.

Tsunami Pictures

http://fohn.net/biggest-tsunami/The biggest tsunami’s of all time – 5 short case studies – try not to use the old ones!

Stromboli

Stromboli• 2002 tsunami

• 10m high

• Tsunamigenic source of a submarine and a sub-aerial landslide, created 2 waves

• Only affected Stromboli, no other regions suffered severe consequences

• Occurred 8 times since 1920

Stromboli Tectonics

morphology

Bathymetry

• Steep sloping NE flank

• Scar extends to 1700m bsl

• Slope is periodically overloaded and collapses (40 degrees, loose pc and lava)

Background to 2002

Stromboli 2002

Hazard Management

Management Techniques

• Standards – education, planning, hazard maps, monitoring and prediction

• Japan – Tsunami Walls (Tsu)• http://water.wikia.com/wiki/Tsunami• Slope stabilisation• Mitigation – setting of smaller

landlsides to minimise risk of big ones!

Management of Risk

• How do you manage tsunami risk?

• 10 Minutes – discuss in groups approaches to management using text book and modules and your own research