Japan EQ & Tsunami

Japan’s Earthquake &Tsunami: 

Japan’s Earthquake &Tsunami What does it mean for us as engineers? (REUTERS/Kyodo ) (REUTERS) (REUTERS)

PowerPoint Presentation: 

The earthquake occurred 130 km (80 miles) east of Sendai and 373 km (231 miles) northeast of Tokyo. Images courtesy of the US Geological Survey Magnitude 9.0 NEAR THE EAST COAST OF HONSHU, JAPAN Friday, March 11, 2011 at 05:46:23 UTC

PowerPoint Presentation: 

Magnitude 9.0 NEAR THE EAST COAST OF HONSHU, JAPAN Friday, March 11, 2011 at 05:46:23 UTC This is one of the largest earthquakes that Japan has ever experienced. . USGS Part of houses swallowed by tsunami burn in Sendai, Miyagi Prefecture (state) after Japan was struck by a strong earthquake off its northeastern coast Friday, March 11, 2011. New York Times In downtown Tokyo, large buildings shook violently. Elsewhere severe flooding occurred due to a tsunami generated by the earthquake.

PowerPoint Presentation: 

Tsunami waves swept away houses and cars in northern Japan and pushed ships aground. The tsunami waves traveled far inland, the wave of debris racing across the farmland, carrying boats and houses with it. Houses were washed away by tsunami in Sendai, Miyagi Prefecture in eastern Japan, after Japan was struck by a magnitude 9.0 earthquake off the northeastern coast. New York Times The earthquake caused some damage – but the tsunami was devastating The tsunami, seen crashing into homes in Natori, Miyagi prefecture. AP

PowerPoint Presentation: 

CNN reported “The quake rattled buildings and toppled cars off bridges and into waters underneath. Waves of debris flowed like lava across farmland, pushing boats, houses and trailers toward highways.” A number of fires broke out including one at an oil refinery which was burning out of control. Giant fireballs rise from a burning oil refinery in Ichihara, Chiba Prefecture (state) after Japan was struck by a strong earthquake off its northeastern coast Friday, March 11, 2011. Los Angeles Times Fires after earthquakes are often caused by broken gas pipelines

PowerPoint Presentation: 

Let’s take a look at tsunami as it hits the east coast of Japan http://www.bbc.co.uk/news/world-asia-pacific-12725646

What do you know about tsunamis? #1: 

What do you know about tsunamis? #1 The speed of a tsunami wave in the open ocean? 15 MPH (speed of a fast distance runner) 75 MPH (speed of a car) 200 MPH (speed of Japan’s bullet train) 475 MPH (speed of a jet plane) 762 MPH (speed of sound)

What do you know about tsunamis? #2: 

What do you know about tsunamis? #2 A tsunami is a single wave . True False

PowerPoint Presentation: 

Globally, this is the 5 th largest earthquake since 1900 (or 4 th depends on M). Chile 1960 Alaska 1964 Sumatra 2004 Chile 2010 Japan 2011 Russia 1952 Ecuador 1906 Alaska 1965

What do you know about tsunamis? #3: 

What do you know about tsunamis? #3 A volcano or an underground landslide can produce a tsunami. True False

PowerPoint Presentation: 

Tsunami ( harbor wave ) Seismic sea waves ( NOT tidal waves) Caused by processes that abruptly move large volumes of ocean water: earthquake submarine volcanic eruption coastal/submarine landslide or rockfall extraterrestrial impact

How do EQ cause tsunami?: 

How do EQ cause tsunami? http://geology.com/articles/tsunami-geology.shtml

Tsunami causes: 

Tsunami causes Unless there is an underwater landslide, strike-slip EQ WILL NOT cause tsunami Most tsunami generated by subduction zones Chile Alaska Japan Cascadia Philippines Caribbean New Zealand

PowerPoint Presentation: 

The map on the right shows historic earthquake activity near the epicenter (star) from 1990 to present. As shown on the cross section, earthquakes are shallow (orange dots) at the Japan Trench and increase to 300 km depth (blue dots) towards the west as the Pacific Plate dives deeper beneath Japan . Images courtesy of the US Geological Survey The earthquake occurred on a subduction zone Seismicity Cross Section across the subduction zone showing the relationship between color and earthquake depth .

What do you know about tsunamis? #4: 

What do you know about tsunamis? #4 The height of a tsunami wave in the open ocean? 1 to 2 inches 1 to 2 feet 10 to 20 feet 30 to 50 feet

Tsunami wavelength: 

Tsunami wavelength Long wavelengths (over 100 km) Periods longer than 1 hour 316,800 ft = 60 miles

Tsunami wave speed: 

Tsunami wave speed Travel at high speeds : 400 to 500 mph (~200 yards/sec) Alaska to CA 4 to 7 hrs Alaska to Hawaii 4 to 6 hrs Chile to Hawaii 14 to 15 hrs Chile to Japan 22 to 33 hrs

PowerPoint Presentation: 

Nearby the earthquake there are only minutes to evacuate. However, in many other regions there is advance warning. A tsunami map shows projected travel times for the Pacific Ocean. This map indicates forecasted times only, not that a wave traveling those distances has actually been observed.. NOAA Projected travel times for the arrival of the tsunami waves across the Pacific

Tsunami wave speed: 

Tsunami wave speed v = speed ~ g = acceleration of gravity (9.8 m/sec 2 ) d = depth of ocean (m) deeper water means higher speed For d = 4,600 m, v = 763 km/hr (speed of jet plane)

What happens when tsunami gets near shore?: 

What happens when tsunami gets near shore? Tsunami slows down (shallower water) Example: d = 100 m, v = 113 km/hr Wave gets taller λ gets shorter, T gets shorter

Tsunami nears shore: 

Tsunami nears shore As wave gets into shallow water bottom of wave drags along ocean floor Top of wave still moving fast: can cause cresting of wave, and breaking onto shore

PowerPoint Presentation: 

This tsunami propagation forecast model shows the forecast maximum tsunami wave height (in cm). Ocean floor bathymetry affects the wave height because a tsunami moves the seawater all the way to the floor of the ocean. This led to a Pacific wide tsunami warning being issued. Scientists Forecast Wave Propagation

Tsunami run-up: 

Tsunami run-up Run-up = measurement of height of water onshore observed above a reference sea level Generally don’t get big gigantic wave Water comes as a fast moving rise in tide that rapidly moves inland NOT JUST ONE WAVE… multiple waves coming in about ½ hour or so apart See tsunami wave simulator http://www.seed.slb.com/en/scictr/watch/living_planet/tsunami_wave/index.htm

Energy in tsunami: 

Energy in tsunami Loss of energy in a wave is inversely proportional to λ Since λ very long, little energy lost Waves can travel great distances and still be very distructive

Damage due to tsunami: 

Damage due to tsunami Waves often full of debris (trees, cars, pieces of wood etc.) As the wave recedes, the debris drags more stuff with it Can recede as much as a km out to sea, leaving shoreline empty with flopping fish, boats, etc. on the bottom

Local Damage from Tsunami: 

Local Damage from Tsunami $17 million+ in Santa Cruz Docks Boats (17 sunk, 50 damaged) $50 million statewide

PowerPoint Presentation: 

Let’s take a look at what Japan looks like before and after http://www.abc.net.au/news/events/japan-quake-2011/beforeafter.htm

Detecting a tsunami: 

Detecting a tsunami Pressure recorder on bottom of ocean Buoy to communicate readings via satellite Tsunami Warning Centers issue warning

PowerPoint Presentation: 

Magnitude 9.0 NEAR THE EAST COAST OF HONSHU, JAPAN Friday, March 11, 2011 at 05:46:23 UTC The DART II® system consists of a seafloor bottom pressure recording (BPR) system capable of detecting tsunamis as small as 1 cm, and a moored surface buoy for real-time communications. DART II has two-way communications between the BPR and the Tsunami Warning Center (TWC) using the Iridium commercial satellite communications system. The two-way communications allow the TWCs to set stations in event mode in anticipation of possible tsunamis or retrieve the high-resolution (15-s intervals) data in one-hour blocks for detailed analysis. DART II systems transmit standard mode data, containing twenty-four estimated sea-level height observations at 15-minute intervals, once very six hours. NOAA

Tsunami Warning Centers: 

Tsunami Warning Centers Hawaii and Alaska When EQ considered capable of generating tsunami, send warning with estimated arrival time Once tsunami hits somewhere, tsunami watch established to monitor tide gauges and ocean buoys

PowerPoint Presentation: 

Tsunami monitoring systems have been strategically deployed near regions with a history of tsunami generation, to ensure measurement of the waves as they propagate towards coastal communities and to acquire data critical to real-time forecasts. Tsunami Monitoring Systems Locations of NOAA’s National Data Buoy Center (NDBC) DART stations comprising the operational network .

Tsunami Warning: 

Tsunami Warning When warning is issued – low lying areas are evacuated U.S. Coast guard issues warnings over marine frequencies Some places have sirens

PowerPoint Presentation: 

Tsunami How could you evaluate the level of risk due to tsunami?

PowerPoint Presentation: 

Possible tsunami “run-up” zones

Seiche: 

Seiche S tanding wave in an enclosed or partially enclosed body of water (similar to sloshing in a bath tub) http://earthquake.usgs.gov/learning/glossary.php?term=seiche Generated by wind or seismic activity Often swimming pools experience a seiche during EQ standing wave

Seiche potential in Lake Tahoe: 

Seiche potential in Lake Tahoe Scientists at UNR have determined the seiches have occurred on Lake Tahoe in the past Low probability – on average once every 2000 to 3000 years Good page on seiches w/great animation http://earthguide.ucsd.edu/earthguide/diagrams/waves/swf/wave_seiche.html