Early forecasting of tsunami inundation from tsunami and geodetic observation data with convolutional neural networks

Rapid and accurate hazard forecasting is important for prompt evacuations and reducing casualties during natural disasters. In the decade since the 2011 Tohoku tsunami, various tsunami forecasting methods using real-time data have been proposed. However, rapid and accurate tsunami inundation forecasting in coastal areas remains challenging. Here, we propose a tsunami forecasting approach using convolutional neural networks (CNNs) for early warning. Numerical tsunami forecasting experiments for Tohoku demonstrated excellent performance with average maximum tsunami amplitude and tsunami arrival time forecasting errors of ~0.4 m and ~48 s, respectively, for 1,000 unknown synthetic tsunami scenarios. Our forecasting approach required only 0.004 s on average using a single CPU node. Moreover, the CNN trained on only synthetic tsunami scenarios provided reasonable inundation forecasts using actual observation data from the 2011 event, even with noisy inputs. These results verify the feasibility of AI-enabled tsunami forecasting for providing rapid and accurate early warnings.

SILENT SIMULATION: THE ABILITY OF GEOGRAPHY EDUCATION STUDENTS TO DO A HORIZONTAL EVACUATION TO A TSUNAMI SAFE ZONE IN PADANG CITY

This article was written to explain the ability of Geography Education students to do horizontal evacuation to a tsunami safe zone in Padang City and a silent simulation as an alternative of horizontal evacuation. In this research, respondents were asked to do horizontal evacuation in 3 ways, that is walking, power walking and running. The measurement result data were analyzed and compared with the estimated arrival time of tsunami wave in three scenarios based on gender. The results of the research are 1) 47.76 % of respondents did not know the nearest tsunami safe zone from their places; 2) if the earthquake and tsunami scenarios 1 and 2 occurred, the recommended horizontal evacuation technique was running. Silent simulation is a horizontal evacuation simulation carried out independently by residents without waiting for the simulation schedule by the government or related institutions. Silent simulation can be done alone, with family, or with the closest neighbours and combined with daily activities such as marathons or jogging. Through this silent simulation practice, residents can find out the most appropriate evacuation method and the fastest evacuation route to the nearest tsunami safe zone from their respective homes.Keywords: silent simulation, geography education, tsunami safe zone, PadangArtikel ini ditulis untuk menjelaskan kemampuan mahasiswa Pendidikan Geografi dalam melakukan evakuasi horizontal ke zona aman tsunami di Kota Padang dan silent simulation sebagai alternatif evakuasi horizontal. Dalam penelitian ini, responden diminta melakukan evakuasi horizontal dengan 3 cara, yaitu jalan kaki, jalan cepat dan lari. Data hasil pengukuran dianalisis dan dibandingkan dengan perkiraan waktu tiba gelombang tsunami pada tiga skenario berdasarkan jenis kelamin. Hasil penelitian adalah 1) 47,76% responden tidak mengetahui zona aman tsunami terdekat dari tempatnya; 2) jika terjadi gempa bumi dan tsunami skenario 1 dan 2, maka teknik evakuasi horizontal yang direkomendasikan adalah berjalan. silent simulation merupakan simulasi evakuasi horizontal yang dilakukan secara mandiri oleh warga tanpa menunggu jadwal simulasi oleh pemerintah atau instansi terkait. silent simulation bisa dilakukan sendiri, bersama keluarga, atau dengan tetangga terdekat dan dipadukan dengan aktivitas sehari-hari seperti maraton atau jogging. Melalui latihan silent simulation ini, warga dapat mengetahui metode evakuasi yang paling tepat dan jalur evakuasi tercepat menuju zona aman tsunami terdekat dari rumah masing-masing.Kata Kunci: Silent simulation, Pendidikan geografi, Zona aman tsunami, Padang

A STUDY ON OPTIMAL DEPLOYMENT OF TSUNAMI OBSERVATION INSTRUMENTS IN KOREA

Tsunamis are one of the most destructive natural phenomena (Pugh and Woodworth, 2014). For past decades, the risk of potential earthquake zones has been issued by Japanese researchers, which could occur tsunami, in Niigata and Tottori area located in the west coast of Japan and the Ryukyu trench located in Okinawa as well (Disaster Prevention Research Institute, Japan). Also, there is a Yamamoto Rise on the East Sea, where it strongly affects tsunami propagation. This topography causes high tsunami energy to concentrate on the east coast of Korea (Cho and Lee, 2013). For example, the 1983 Akita and 1993 Hokkaido earthquake induced tsunamis, Japan, respectively cause the property and life damages to the certain cities on the east coast of Korea. Therefore, it is important to propose the optimal deployment location of offshore tsunami observation instruments to contribute to the tsunami early warning system by increasing probability of tsunami detection with the minimal number of instruments considering a large number of potential tsunami scenarios. In this study, by considering various factors, the optimal location of instruments is suggested based on the numerical model results of possible tsunami scenarios.Recorded Presentation from the vICCE (YouTube Link): https://youtu.be/q3PLE6EgtrY

A NUMERICAL MODEL FOR THE EFFICIENT SIMULATION OF MULTIPLE LANDSLIDE-TSUNAMI SCENARIOS

Submarine landslides can pose serious tsunami hazard to coastal communities, occurring frequently near the coast itself. The properties of the tsunami and the consequent inundation depend on many factors, such as the geometry, the rheology and the kinematic of the landslide and the local bathymetry. However, when evaluating the risk related to landslide tsunamis, it is very difficult to accurately predict all of the above mentioned parameters. It is therefore useful to carry out many simulations of tsunami generation and propagation, with reference to different landslide scenarios, in order to deal with such uncertainties (see for example the probabilistic approach by Grilli et al. 2009). Accurate computations of landslide tsunami generation, propagation, and inundation, however, is computationally expensive, thus limiting the possible maximum number of scenarios. To partially overcome this difficulty, in the present research, a numerical model is proposed that can efficiently compute a large number of tsunami simulations triggered by different landslides. The main goal is to provide a numerical tool that can be used in a Monte Carlo approach framework. Following the study by Ward (2001), we propose a methodology taking advantage of the linear superposition of elementary tsunami solutions.Recorded Presentation from the vICCE (YouTube Link): https://youtu.be/uYOvdsutmBw

Uncertainty quantification of tsunami inundation in Kuroshio, Kochi Prefecture, Japan, using the Nankai–Tonankai megathrust rupture scenarios

Nankai–Tonankai megathrust earthquakes and tsunamis pose significant risks to coastal communities in western and central Japan. Historically, this seismic region hosted many major earthquakes, and the current national tsunami hazard assessments in Japan consider megathrust events as those having moment magnitudes between 9.0 and 9.1. In responding to the lack of rigorous uncertainty analysis, this study presents an extensive tsunami hazard assessment for the Nankai–Tonankai Trough events, focusing on the southwestern Pacific region of Japan. A set of 1000 kinematic earthquake rupture models is generated via stochastic source modelling approaches, and Monte Carlo tsunami simulations are carried out by considering high-resolution grid data of 10 m and coastal defence structures. Significant advantages of the stochastic tsunami simulation methods include the enhanced capabilities to quantify the uncertainty associated with tsunami hazard assessments and to effectively visualize the results in an integrated manner. The results from the stochastic tsunami simulations can inform regional and local tsunami risk reduction actions in light of inevitable uncertainty associated with such tsunami hazard assessments and complement conventional deterministic tsunami scenarios and their hazard predictions, such as those developed by the Central Disaster Management Council of the Japanese Cabinet Office.

Probabilistic tsunami inundation assessment of Kuroshio Town,Kochi Prefecture, Japan considering the Nankai-Tonankai megathrust rupture scenarios

The Nankai-Tonankai megathrust earthquake and tsunami pose significant risks to coastal communities in western and central Japan. Historically, this seismic region hosted many major earthquakes, and the current national tsunami hazard assessments in Japan consider megathrust events having moment magnitudes between 9.0 and 9.1. In responding to the lack of rigorous uncertainty analysis, this study presents an extensive tsunami hazard assessment for the Nankai-Tonankai Trough events, focusing upon the southwestern Pacific region of Japan. A set of 1,000 kinematic earthquake rupture models is generated via stochastic source modelling approaches, and Monte Carlo tsunami simulations are carried out by considering high-resolution grid data of 10-m and coastal defense structures. Significant advantages of the stochastic tsunami simulation methods include the enhanced capabilities to quantify the uncertainty associated with tsunami hazard assessments and to effectively visualize the results in an integrated manner. The results from the stochastic tsunami simulations can inform regional and local tsunami risk reduction actions in light of inevitable uncertainty associated with such probabilistic tsunami hazard assessments, and complement conventional deterministic tsunami scenarios and their hazard predictions, such as those developed by the Central Disaster Management Council of the Japanese Cabinet Office.