JMA Tsunami Warning Services. Takeshi KOIZUMI Senior Coordinator for International Earthquake and Tsunami Information Japan Meteorological Agency

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1 JMA Tsunami Warning Services Takeshi KOIZUMI Senior Coordinator for International Earthquake and Tsunami Information Japan Meteorological Agency

2 Tectonic Setting of Japan (Headquarters for Earthquake Research Promotion)

3 Time Sequence of Earthquake Information and Tsunami Warning in JMA Earthquake Early Warning Tsunami Information (Estimated Tsunami Heights and Arrival Times) Tsunami Warning Seismic Intensity Information Earthquake Information (Hypocenter and Magnitude ) Earthquake and Seismic Intensity Information Tsunami Information (Observed Tsunami Heights and Arrival Times) Seismic Intensity Information at each Site

4 Seismic Network in Japan : 津波地震観測装置等 (220 地点 ) ( 内多機能型地震計 Seismic station 215 地点 ) : 海底地震計 (3 式 ) : 群列地震観測システム (1 式 ) : 各種特殊地震計 (1 式 ) Ocean-bottom seismic sensor Seismic array system Seismic Intensity Stations Standard Station :JMA :Local Government ,919 :NIED Total : 4,316 JMA s Seismic Network Sensors

5 Earthquake Data Processing System Osaka Tokyo To process seismological data, and make and issue earthquake and tsunami information, JMA developed EPOS (Earthquake Phenomena Observations System). EPOS is located in Tokyo and Osaka. Tokyo-EPOS and Osaka-EPOS work in parallel, and function as back-up system one another.

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8 Determination of Hypocenter and Magnitude The 2011 off the Pacific coast of Tohoku Earthquake For each station : P-phase arrival time S-phase arrival time Maximum amplitude

9 Database for Tsunami Warning Preparation -- Create Tsunami Database distribution of assumed faults 1,500 (horizontal direction) 6 (vertical direction, km) 4 (magnitude) some mechanism = about 100,000 scenarios Calculate Crustal Movement for each Assumed Fault Arrival Time & Height Tsunami Database Tsunami Database Computer Simulation of Tsunami Propagation 9

10 Fault Parameter and Tsunami Source Fault model - Reverse fault given by epicenter given by scaling law log L= 0.5M-1.9 (M:magnitude) W = L/2 logd = 0.5M-3.2 given in advance 45degree (fixed) 90degree (fixed) Dip angle is set which general tsunami most effectively. λ=0(strike-slip), 20 and 80 are also assumed. Tsunami source - Crustal deformation on the sea floor calculated by the elastic theory (Okada, 1985) - Initial tsunami height distribution is assumed to be same shape as the sea floor deformation

11 Strike Angle (φ) of the Assumed Faults Strike angle (degree)

12 Interpolation for Cases Far from the Shore Estimation of arrival time ---> choose the severest (earliest) case

13 Maximum Risk Method for Cases Close to the Shore Maximum risk method is used in case epicenter is near the coast. It is because starting point of the fault rupture cannot be known immediately. The maximum extent of the possible fault Light blue area is searched (whose centers are involved in a light orange area) L 5 D epicenter f(epicenter) = max{1,2,3,4,5} :Maximum Risk Method (Spacing between the hypothetical epicenters) where, logl = 0.5M 1.9

14 Estimation of Tsunami Height at the Coast Forecast Point (Height: H 1, Depth: h 1 ) Coastal Point (Height:H, Depth:h) Tsunami numerical simulation Application of Green s Law Forecast Point (H 1 h 1 ) Coastal Point (H h) H 4 h 1 H1 h JMA substitute 1m for h

15 Tsunami Warning Classification Type of Tsunami Bulletin Tsunami Warning Major Tsunami Tsunami Tsunami Advisory Estimated Tsunami Height "3m", "4m", "6m", "8m", "over 10m" "1m", "2m" "0.5m" 66 Regional Blocks for Tsunami Warning/Advisory

16 Tsunami Monitoring Network in Japan : Tide Gauges(on the coast) JMA (77), Others(95) : GPS Buoy : Tsunameter JMA (6), ERI (2), JAMSTEC (4) Total: Tsunameter data is under evaluation (12/05/2011) Tide Gauges GPS Buoy Tsunameter

17 Dissemination of Tsunami Warning and Earthquake Information satellite Local Governments Loud Speakers Sirens Police, Fire offices Residents in coastal areas at risk Dedicated Telephone Line TV broadcasting On TV, radio, etc. JMA as the National Center Central Government Radio Stations etc.

18 Provision of Tsunami Bulletins to countries around the Northwest Pacific and the Indian Ocean Japanese Seismic Network Pacific Tsunami Warning Center (PTWC) Information Exchange Global Seismic Network Tsunami Bulletins (NWPTA)*1 (TWI)*2 Indian Ocean Northwest Pacific Ocean Sea Level Stations Data JMA Analysis Hypocenter Magnitude Evaluation of Tsunamigenic Potential Tsunami Observation etc. Contribute to the mitigation of tsunami disasters of countries around the Northwest Pacific and the Indian Oceans *1) NWPTA: Northwest Pacific Tsunami Advisory *2) TWI: Tsunami Watch Information for the Indian Ocean

19 EEW

20 Concept of Earthquake Early Warning (EEW) 1 The EEW System automatically calculates the earthquake epicenter and magnitude from the P-waves detected near the epicenter, then estimates the strengths of following ground shaking (seismic intensities) at numbers of cities, towns and villages. 2 An EEW is provided a few seconds to a few tens of seconds before the S-wave or strong tremor arrival. Strong tremors may hit areas close to the earthquake focus at the same time as the Earthquake Early Warning.