Brian Shiro NOAA Pacific Tsunami Warning Center

SOI R/V Falkor 22 May 2014

Tsunami Warning at PTWC

Japan – 11 March 2011

The word “tsunami”

Sometimes tsunamis are incorrectly called “tidal waves” or “seismic sea waves.”

“tsu” = harbor

“nami” = wave

What is a tsunami? A tsunami is a series of long-period waves created by an abrupt disturbance that displaces a large amount of water. Caused by:

72%

2%

10%

11%

5%EarthquakesLandslidesVolcanoesAtmosphereOther/Unknown

source: NOAA NGDC

Iceberg calving, Asteroid impact (no recorded history)

59%

12%

25%

4%

PacificMediterraneanAtlanticIndian

Where do tsunamis occur?

Whole Historical Record

77%

10%

9%

4%

PacificMediterraneanAtlanticIndian

Just 1900-present (no Mediterranean bias)

source: NOAA NGDC

Earthquakes (1900-2006)

source: USGS NEIC

Local/Regional tsunamis

with deaths <1000 km from source

source: USGS NEIC

Ocean-wide tsunamis

with deaths >1000 km from source

source: USGS NEIC

Ring of Fire

Subduction zones produce Earthquakes, Volcanoes, & Tsunamis.

Normal vs. Tsunami waves Normal Waves:

•  Movement of uppermost layer of water only, motion diminishes with depth

•  Caused by wind or storm surge •  Wavelength: 30-200 m, Period: 1-30 s •  Speed: 15-115 km/h

(function of wave period à dispersive)

Tsunami Waves: •  Movement of entire water column

down to sea floor •  Caused by tides or tsunamis •  Wavelength: 80-500 km, Period: 5-60 m •  Speed: 50-900 km/h

(function of depth only)

h

Called “Deep Water Waves” because h > L/2

L

h h

Called “Shallow Water Waves” because h < L/20

L

h

Tsunami waves are fast …

about 900 km/hr

The deeper the water, the faster the tsunami. V = sqrt(g*h)

but seismic waves are faster! Seismic waves travel at the speed of sound in rock: •  about 16-25,000 km/hr

Tsunami waves are much slower than seismic waves: •  about 50-900 km/hr

Therefore, it is possible to issue a warning for a tsunami ahead of its arrival!

Pacific Tsunami Warning Center •  Established in 1949

(following 1946 tsunami) •  International center for

Pacific Ocean since 1969 (following 1960 tsunami)

•  Interim center for Indian Ocean 2005-2013 (following 2004 tsunami)

•  Interim center for Caribbean Sea since 2007

PTWC Scientific Staff tripled from 4-12 in 2005. (2 watchstanders on duty 24x7)

PTWC is moving to its new home on Ford Island, Pearl Harbor in 2014.

PTWC AOR as of 2014

Alarm!

PTWC Operations 1.  Seismic Analysis 2.  Message

Dissemination 3.  Tsunami

Forecasting 4.  Sea Level

Monitoring

Step 1: Seismic Analysis Determine: Location, Origin time Depth, and Magnitude

Sources: IRIS, USGS, IMS, etc.

Seismic Network

Earthquake Magnitude 1 magnitude change = 32 times of energy increase

PTWC Operations 1.  Seismic Analysis 2.  Message

Dissemination 3.  Tsunami

Forecasting 4.  Sea Level

Monitoring

Step 2: Message Dissemination If the earthquake is in PTWC’s AOR, shallow (< 100 km), and meets a magnitude threshold, PTWC will issue a tsunami message. Magnitude (MW) Message Type

6.5-7.5 Tsunami Information Bulletin

7.6-7.8 Fixed Regional Tsunami Warning

≥7.9 Expanding Regional Tsunami Watch/Warning

Large tsunami confirmed

Pacific Ocean-wide Tsunami Warning

Pacific Ocean Warning Criteria

Message Pathways AFTN

airports worldwide GTS/NMC international

NWW USA & Canada

Telex Chile

IDN Hawaii

HAWAS Hawaii

NAWAS USA & Canada

Telephone warning points

FAX warning points

Website anyone

Email anyone

RSS Feeds anyone

EMWIN warning points

SMS RANET

text phone

internet

PTWC Operations 1.  Seismic Analysis 2.  Message

Dissemination 3.  Tsunami

Forecasting 4.  Sea Level

Monitoring

Step 3: Tsunami Forecasting Computing tsunami arrival time is easy. •  Analytical calculation

Estimating tsunami amplitude at the shore is harder. •  Numerical computation

Scenario: M9 in Kuril Islands

Hypothetical Scenario Illustrates PTWC’s new RIFT model-based products coming in late 2014

Example: M8.3 Kuril Islands, 15 Nov 2006

Runup and Inundation

Inundation Zone Maps

PTWC Operations 1.  Seismic Analysis 2.  Message

Dissemination 3.  Tsunami

Forecasting 4.  Sea Level

Monitoring

Step 4: Sea Level Monitoring Measure and record ocean height at a sea level gauge (often called “tide gauge”. Transmission delays vary from near real time to up to an hour. Different styles: •  Float-operated •  Pressure sensor •  Radar

Sources: GLOSS, NOAA, UHSLC, etc.

Sea Level Network

DART System Deep-ocean Assessment and Reporting of Tsunamis 44 worldwide (34 in Pacific) Operated by NOAA NDBC

The future

(Smith et al 2005) (Occhipinti et al 2008)

satellite altimetry ionospheric TEC

GPS, over-the-horizon radar, infrasound, and …

Tsunami Safety for Boaters

Pau

Brian Shiro brian.shiro@noaa.gov

Pacific Tsunami Warning Center http://ptwc.weather.gov

Extra Slides

Tsunami Warning Products Tsunami Warning. A damaging tsunami is expected. Coastal evacuation is necessary. (Forecasted tsunami amplitude is >1 m)

Tsunami Advisory. A tsunami is expected, but it is not expected to be large enough to cause more than minor flooding. Evacuation is not necessary, but stay off the beach and out of the water. (Forecasted tsunami amplitude is 0.3-1 m)

Tsunami Watch. An earthquake has occurred which may have generated a damaging tsunami. The tsunami is at least three hours away.

Tsunami Information Bulletin. A large earthquake has occurred but no tsunami is expected.

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