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Notes From the Field...

The March 11, 2011 Tsunami

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USGS PCMSC Tsunami and Earthquake Studies

 

The March 11, 2011 Tsunami

Photo of damage in Natori, Japan.

On March 11, 2011 a magnitude 9.0 “great” earthquake off the east coast of Japan generated a Pacific-wide tsunami that was catastrophic along the coast of northeastern Honshu, Japan. The first tsunami wave arrived at the Honshu coastline nearest to the epicenter within about 15 minutes of the earthquake with subsequent waves arriving in the hours that followed, in places 10m or more in height. Entire communities were flooded by the waves and substantial infrastructure was damaged.

International Tsunami Survey Team Visits Japan, May 2011

PCMSC Oceanographer Bruce Jaffe and Geologist Bruce Richmond visited Japan, collecting time-sensitive data to help them determine the height of tsunami waves at various sites and the distances the waves traveled inland. They studied the transport of sediment and other debris, looked for and measured evidence of subsidence and uplift caused by the earthquake, documented erosion caused by the tsunami waves, and made other observations critical to the better understanding of tsunami impacts and processes.

May 6, 2011, Bruce Jaffe:

Amazing devastation- the tsunami inundated 4 km where I am working. Tsunami flow depths of 10 m near the coast. Inundation distances > 4 km. Huge amounts of debris (pieces of houses, cars, etc.). More than 100,000 cars were destroyed by the tsunami in the area. That's 10% of all the cars. [It appears that] the earthquake did very little damage.

Photo from Japan, May 2011.
Erosion in back of the Arahama Beach seawall, Sendai.
Photo from Japan, May 2011.
Tree snap indicating onshore flow at Arahama Beach, Sendai.
Photo from Japan, May 2011.
Scientists running a transect at the Sendai airport.
Photo from Japan, May 2011.
Mountain of debris cleaned out of Natori, south of Sendai.
Photo from Japan, May 2011.
Debris wrapped around structure in Natori, south of Sendai.
Photo from Japan, May 2011.
Clean-up continues near the limit of inundation in Natori, south of Sendai.
Photo from Japan, May 2011.
Damage indicates a 10m flow depth. Natori, south of Sendai.
Photo from Japan, May 2011.
Foundations in Natori, south of Sendai.
Photo from Japan, May 2011.
ITST Scientist Nishimura-sensei demonstrating the tool called the “geoslicer”
Photo from Japan, May 2011.
Clean-up pile at Iwanuma Seaside Park, South of Natori.

Photos and Observations on March 11, 2011 in California and Hawaii

Map of Santa Cruz, CA showing locations of photos and videos featured below.The tsunami also propagated across the Pacific Ocean and was measured both by oceanic buoys and by coastal tide stations. As noted by the International Tsunami Information Center (http://itic.ioc-unesco.org/):

  • Hawaii ordered statewide evacuations as waves of over 2m passed the islands;
  • the west coast of the United States experienced waves of over 4m (trough to peak) at Crescent City; and
  • waves of over 4m (trough to peak) were measured down the coast of Chile.
At right, map showing locations in Santa Cruz where photos and videos were taken. Click for larger version.We present initial field observations from central California and Hawaii gathered by members of the USGS Pacific Coastal and Marine Science Center. The tsunami caused damage to harbors in California, most notably at Crescent City and Santa Cruz. In general, open coast settings exhibited little damage from the waves, in part because the largest waves arrived at low tide.

 

Seacliff State Beach (B. Jaffe) Map popup

Crowd Watching tsunami come in.
Crowd on top of cliff at Seacliff State Beach, CA watching the tsunami waves come in. [Larger version]
Crowd watching tsunami.
Safe tsunami tourists waiting on top of a cliff at Seacliff Beach, CA for the tsunami to come in. [Larger version]
Exposed paint at drawdown.
Red paint exposed on the concrete ship Palo Alto during drawdown of the tsunami at 9:09 am. Drawdown is about 1-1.5 m. The normal low water level is at the boundary between the orange paint and gray-green biologic growth band. [Larger version]
Crowd in danger zone.
Tsunami tourist walking in an unsafe zone exposed by the tsunami drawdown at 9:10 am. Fortunately, the tsunami was like a slow moving tide (not always the case, it can be a fast moving bores) and the people in this photo moved out of the danger zone before the tsunami crest came in. [Larger version]
Drawdown from tsunami.
Onlooker sees sand bar that is usually underwater exposed by the tsunami drawdown at 9:16 am. [Larger version]
Crest of tsunami wave.
Water level when the tsunami crest came onshore. The tsunami arrived at a low tide (about 0.3 m above mean lower low water). As a result, the tsunami did not inundate as far as it would have had the tide been high. The waves in this photograph are from a distant swell, not the tsunami. [Larger version]

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Seacliff State Beach (B. Richmond) Map popup

  • At least 3 significant water level drawdowns occurred over several hours.
    Incoming waves did not exceed the pre-tsunami high-water mark.
  • All campers evacuated to higher ground (mandatory).
    No significant damage observed in the area.
  • Hundreds of onlookers lined the coastal bluffs;
    dozens of citizens ignored warnings and walked along beach pathways.
Max drawdown Seacliff Beach.
Cement ship SS Palo Alto and pier at maximum drawdown [Larger version]
Cement ship and pier at Seacliff.
Palo Alto stern and pier at maximum drawdown [Larger version]
Aptos Creek mouth.
Aptos Creek mouth at maximum drawdown [Larger version]
Incoming bore.
Incoming wave bore at Aptos Creek [Larger version]
Exposed sandbar at max drawdown.
Exposed sand bar at maximum drawdown – Seacliff State Beach [Larger version]
Danger zone.
Tsunami tourist on the beach during maximum drawdown – not a recommended practice! [Larger version]

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Santa Cruz Harbor Map popup

Photo of Santa Cruz Harbor.
Photo of Santa Cruz Harbor looking seaward from the Murray Street bridge (J. Hansen) [Larger version]
Photo of Santa Cruz Harbor.
Photo of Santa Cruz Harbor looking seaward from the Murray Street bridge (J. Hansen) [Larger version]
Photo of Santa Cruz Harbor.
Photo in Santa Cruz Harbor looking under the Murray Street bridge (J. Hansen) [Larger version]

Videos from Santa Cruz Harbor (J. Hansen)

U-dock in Santa Cruz Harbor during early stages of tsunami.
U-dock in Santa Cruz Harbor (as seen from the Murray Street railroad bridge) at 8:23am (A. Foxgrover) [Larger version]
U-dock later in the day of the tsunami.
U-dock in Santa Cruz Harbor (as seen from the Murray Street railroad bridge) at 1:40pm (A. Foxgrover) [Larger version]

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Hawaii (C. Storlazzi)

PUHE visitor center.
View looking west from National Park Service's (NPS) Pu`ukohola Heiau (PUHE) National Historic Site's park offices on Friday 03/11/2011 at approximately 07:30 AM Hawaii Standard Time (HST) showing large fine-grained terrestrial sediment plume being advected offshore by the retreating waters. Also note the numerous small brown coral heads sticking 0.5-1.0 m out of the water. These are generally 0.5-1.0 m below Mean Sea Level (MSL).
Pelekane Bay draining.
View looking northwest towards Kawaihae Harbor from PUHE's park offices on Friday 03/11/2011 at approximately 07:30 AM HST showing water draining from Pelekane Bay, exposing the sea floor. Note the dark brown color of the road (which used to be white carbonate sand) adjacent to the bay- this is due to the terrestrial mud from the bay's sea floor being carried up and deposited by the tsunami to an elevation of 2 m above MSL. See detail of road mud and debris below.
Pelekane Bay rack line.
View looking southwest from Kawaihae Harbor on Saturday 03/12/2011 at approximately 01:30 PM HST showing debris along the southwestern breakwater more than 2 m above MSL (Josh Logan, USGS, is 1.7 m tall for scale).
Fish rack about MSL.
Fish and mud deposited on the road ringing Kawaihae Harbor on Saturday 03/12/2011 at approximately 02:00 PM HST. (See road in photo above.)
Pelekane stream bore.
View looking south towards PUHE from Kawaihae Harbor on Saturday 03/12/2011 at approximately 03:30 PM HST showing water draining the breached berm at Pelekane Stream continuing to oscillate up and down approximately 0.3-0.7 m. Pelekane Stream is an intermittent stream that was dry and not flowing above the tsunami oscillations at the time.
Stream gage.
View looking south towards PUHE from Kawaihae Harbor on Saturday 03/12/2011 at approximately 04:00 PM HST showing our in-channel stream gauge (basically a pressure sensor in a perforated pipe). The gauge was initially deployed in the stream channel. A tsunami bore dislodged the 100+ kg rock it was chained around and carried the ~35 kg stream gauge ~20 m upstream and deposited it ~1 m above the channel on a small floodplain.

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Page Last Modified: 25 May 2011 (lzt)