Analysis of Tsunami Hazard Potential in Jakarta Bay from Megathrust Earthquake Scenarios

We developed a clustering method combining principal component analysis and the k-means algorithm, which classifies earthquake scenarios based on the similarity of the spatial distribution of earthquake ground-motion simulation data generated for many earthquake scenarios, and applied it to long-period ground-motion simulation data for Nankai Trough megathrust earthquake scenarios. Values for peak ground velocity and relative velocity response at approximately 80,000 locations in 369 earthquake scenarios were represented by 15 principal components each, and earthquake scenarios were categorized into 30 clusters. In addition, based on clustering results, we determined that extracting relationships between principal components and scenario parameters is possible. Furthermore, by utilizing these relationships, it may be possible to easily estimate the approximate ground-motion distribution from the principal components of arbitrary sets of scenario parameters.

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THE EXISTENCE OF COASTAL FOREST, ITS IMPLICATION FOR TSUNAMI HAZARD PROTECTION, A CASE STUDY: IN CILACAP-CENTRAL JAVA, INDONESIA

BULLETIN OF THE MARINE GEOLOGY ◽

10.32693/bomg.30.1.2015.72 ◽

2016 ◽

Vol 30 (1) ◽

pp. 23 ◽

Cited By ~ 2

Author(s):

Yudhicara Yudhicara

Keyword(s):

Cocos Nucifera ◽

Tsunami Hazard ◽

Coastal Protection ◽

Casuarina Equisetifolia ◽

Coastal Forest ◽

Southern Coast ◽

Coastal Forests ◽

Tsunami Height ◽

Tsunami Waves ◽

Hazard Potential

The southern coast of Java which is facing to the Indian Ocean has many of natural hazard potential come from the sea. Since 2006 tsunami impacted the southern coast of Java, and caused severely damage especially along the coast of Cilacap (1-7,7 m run up height). People commit to do greening the beach by planting suitable plants such as a Casuarina equisetifolia, Terminalia catappa, and Cocos nucifera. This paper discusses the existence of coastal forests in Cilacap coastal area, their potential ability as a coastal protection from the tsunami wave which cover the density, diameter, height, age, and other parameters that affects the coastal defence against tsunami waves. Some experiences of tsunamis that have occurred, indicating that the above parameters linked to the ability of vegetation to act as a natural barrier against tsunamis. In the case of sandy beaches, such as in Cilacap, Pandanus odorarissimus has more effectiveness than other trees due to its hanging roots that can withstand the tsunami height less than 5 m, able to withstand debris and can withstand the scouring effects of tsunami waves, while Casuarina equisetifolia along Cilacap beaches more dominant than other trees, so it is recommended to increase the diversity of plants as well as increase the density and tree placement setting. By field measurement in order to get parameter applied to some graphs, Cilacap coastal forest does not enough capability for tsunami barrier reflected to the tsunami height experience in this region. Ages could be the important parameter in order to have bigger diameter trunk, higher trees height, and high resistance capacity againts tsunami hazard potential. Compare to Kupang, East Nusa Tenggara, Cilacap coastal forest still young and need some more years to make trees ready act as tsunami reduction. Keywords: Cilacap coastal forest, Kupang, tsunami, vegetation parameters. Pantai Selatan Jawa yang berhadapan dengan Samudera Hindia, memiliki banyak potensi mengalami bahaya yang datang dari lautan. Selama tahun 2006, Tsunami telah menimpa sebagian pantai selatan Jawa dan menyebabkan banyak kerusakan parah terutama di sepanjang Pantai Cilacap (tinggi gelombang 1-7,7 m). Masyarakat melakukan penghijauan pantai dengan menanam sejumlah pohon yang sesuai dengan kondisi pantai, seperti pohon cemara pantai (Casuarina equisetifolia), ketapang (Terminalia cattapa) dan kelapa (Cocos nucifera). Tulisan ini membahas penyebaran hutan pantai di wilayah pantai Cilacap, kemampuan dan potensi hutan tersebut sebagai pelindung alami pantai dari bahaya gelombang tsunami, yang terdiri dari kerapatannya, diameter, tingginya, umur, dan parameter lainnya yang mempengaruhi daya tahan pantai terhadap gelombang tsunami. Beberapa pengalaman mengenai kejadian yang telah terjadi, memperlihatkan bahwa parameter tersebut di atas mempengaruhi kemampuan tanaman sebagai penahan alamiah terhadap tsunami. Untuk kondisi pantai berpasir seperti Cilacap, tanaman pandan pantai lebih efektif dibandingkan dengan tanaman lainnya, dikarenakan akarnya yang dapat menahan tinggi gelombang kurang dari 5 m, selain itu akar tersebut dapat menahan material dan erosi vertikal gelombang tsunami, sementara di sepanjang pantai Cilacap, tanaman cemara pantai (Casuarina equisetifolia) lebih dominan dibandingkan tanaman lainnya. Kondisi ini dapat direkomendasikan untuk tetap dipertahankan bahkan ditambah jumlahnya. Di lapangan dilakukan pengukuran parameter tanaman pantai dan hasilnya diplot dalam bentuk grafik dan diaplikasikan dalam grafik yang dibuat berdasarkan hasil penelitian terhadap tsunami di beberapa tempat di dunia terutama di Jepang. Berdasarkan tinggi gelombang maksimum yang pernah terjadi di daerah ini (7,7 m), terlihat bahwa hutan pantai Cilacap belum cukup mampu bertindak sebagai penahan gelombang tsunami. Umur merupakan parameter penting agar pohon memiliki diameter yang besar, pohon yang cukup tinggi dan daya tahan terhadap potensi bahaya tsunami. Dibandingkan dengan hutan pantai di Kupang, Nusa Tenggara Timur, hutan pantai di Cilacap relatif masih muda dan membutuhkan beberapa tahun lagi untuk dapat memperkecil resiko yang ditimbulkan oleh bahaya tsunami. Kata kunci: Hutan pantai Cilacap, Kupang, tsunami dan parameter vegetasi.

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Tsunami hazard in Lombok & Bali, Indonesia, due to the Flores backarc thrust

10.5194/nhess-2021-343 ◽

2021 ◽

Author(s):

Raquel Felix ◽

Judith Hubbard ◽

Kyle Bradley ◽

Karen Lythgoe ◽

Linlin Li ◽

...

Keyword(s):

Maximum Flow ◽

Tsunami Hazard ◽

Earthquake Sequence ◽

Coastal Hazards ◽

Fault System ◽

Northern Coast ◽

Coseismic Slip ◽

Ground Shaking ◽

Tsunami Waves ◽

Earthquake Scenarios

Abstract. The tsunami hazard posed by the Flores backarc thrust, which runs along the northern coast of the islands of Bali and Lombok, Indonesia, is poorly studied compared to the Sunda megathrust, situated ~250 km to the south of the islands. However, the 2018 Lombok earthquake sequence demonstrated the seismic potential of the western Flores Thrust when a fault ramp beneath the island of Lombok ruptured in two Mw 6.9 earthquakes. Although the uplift in these events mostly occurred below land, the sequence still generated 1–2.5 m-high local tsunamis along the northern coast of Lombok (Wibowo et al., 2021). Historical records show that the Flores fault system in the Lombok and Bali region has generated at least six ≥ Ms 6.5 tsunamigenic earthquakes since 1800 CE. Hence, it is important to assess the possible tsunami hazard represented by this fault system. Here, we focus on the submarine fault segment located between the islands of Lombok and Bali (below the Lombok Strait). We assess modeled tsunami patterns generated by fault slip in six earthquake scenarios (slip of 1–5 m, representing Mw 7.2–7.9+), with a focus on impacts on the capital cities of Mataram, Lombok and Denpasar, Bali, which lie on the coasts facing the strait. We use a geologically constrained earthquake model informed by the Lombok earthquake sequence (Lythgoe et al., 2021), together with a high-resolution bathymetry dataset developed by combining direct measurements from GEBCO with sounding measurements from the official nautical charts for Indonesia. Our results show that fault rupture in this region could trigger a tsunami reaching Mataram in < 8 minutes and Denpasar in ~10–15 minutes, with multiple waves. For an earthquake with 3–5 m of coseismic slip, Mataram and Denpasar experience maximum wave heights of ~1.3–3.3 m and ~0.7 to 1.5 m, respectively. Furthermore, our earthquake models indicate that both cities would experience coseismic subsidence of 20–40 cm, exacerbating their exposure to both the tsunami and other coastal hazards. Overall, Mataram city is more exposed than Denpasar to high tsunami waves arriving quickly from the fault source. To understand how a tsunami would affect Mataram, we model the associated inundation using the 5 m slip model and show that Mataram is inundated ~55–140 m inland along the northern coast and ~230 m along the southern coast, with maximum flow depths of ~2–3 m. Our study highlights that the early tsunami arrival in Mataram, Lombok gives little time for residents to evacuate. Raising their awareness about the potential for locally generated tsunamis and the need for evacuation plans is important to help them respond immediately after experiencing strong ground shaking.

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Microzoning Tsunami Hazard by Combining Flow Depths and Arrival Times

Frontiers in Earth Science ◽

10.3389/feart.2020.591514 ◽

2021 ◽

Vol 8 ◽

Author(s):

Natalia Zamora ◽

Patricio A. Catalán ◽

Alejandra Gubler ◽

Matías Carvajal

Keyword(s):

Tsunami Hazard ◽

Mitigation Strategies ◽

Evacuation Planning ◽

Large Set ◽

Proof Of Concept ◽

Arrival Times ◽

Earthquake Scenarios ◽

Pedestrian Evacuation ◽

Great Dependency ◽

Different Sources

Tsunami hazard is typically assessed from inundation flow depths estimated from one or many earthquake scenarios. However, information about the exact time when such inundation occurs is seldom considered, yet it is crucial for pedestrian evacuation planning. Here, we propose an approach to estimating tsunami hazard by combining tsunami flow depths and arrival times to produce a nine-level, qualitative hazard scale that is translated into a simple tsunami hazard map. To do this, one of the most populated regions of the coast of Chile is considered as the sample site, using a large set of 2,800 tsunamigenic sources from earthquakes with magnitudes in the range Mw8.6−9.2, modeled from generation to inundation at high resolution. Main outcomes show great dependency of the hazard categorization on the tsunami time arrival, and less to the flow depths. Also, these results demonstrate that incorporating different sources of variability such as different earthquake magnitudes and locations as well as stochastic slip distributions is essential. Moreover, this proof-of-concept exercise clearly shows that the qualitative hybrid categorization of the tsunami hazard allows for its more effective understanding, which can be beneficial for designing mitigation strategies such as evacuation planning, and its management.

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Review of Tsunami Hazard Potential for Gulf of Aqaba, Egypt

Journal of the Geological Society of India ◽

10.1007/s12594-021-1911-z ◽

2021 ◽

Vol 97 (12) ◽

pp. 1545-1550

Author(s):

Asem Salama ◽

Mohamed El Gabry ◽

Moussa ◽

Hesham Hussein ◽

I. F. Abu El-Nader

Keyword(s):

Tsunami Hazard ◽

Gulf Of Aqaba ◽

Hazard Potential

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Simulated tsunami inundation for a range of Cascadia megathrust earthquake scenarios at Bandon, Oregon, USA

Geosphere ◽

10.1130/ges00899.1 ◽

2013 ◽

Vol 9 (6) ◽

pp. 1783-1803 ◽

Cited By ~ 26

Author(s):

Robert C. Witter ◽

Yinglong J. Zhang ◽

Kelin Wang ◽

George R. Priest ◽

Chris Goldfinger ◽

...

Keyword(s):

Tsunami Inundation ◽

Megathrust Earthquake ◽

Earthquake Scenarios

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The Effects on Tsunami Hazard Assessment in Chile of Assuming Earthquake Scenarios with Spatially Uniform Slip

Pageoph Topical Volumes - Global Tsunami Science: Past and Future, Volume I ◽

10.1007/978-3-319-55480-8_3 ◽

2016 ◽

pp. 3693-3702 ◽

Cited By ~ 1

Author(s):

Matías Carvajal ◽

Alejandra Gubler

Keyword(s):

Hazard Assessment ◽

Tsunami Hazard ◽

Earthquake Scenarios ◽

Tsunami Hazard Assessment

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Assessing future uncertainties: earthquake tsunami hazard in the Java trench, Indonesia.

10.5194/egusphere-egu2020-10762 ◽

2020 ◽

Author(s):

Dimitra Salmanidou ◽

Mohammad Heidarzadeh ◽

Serge Guillas

Keyword(s):

Subduction Zone ◽

Shallow Water Equation ◽

Historical Earthquakes ◽

Tsunami Hazard ◽

Disaster Mitigation ◽

Dislocation Model ◽

Ground Shaking ◽

Wave Amplification ◽

Earthquake Scenarios ◽

Tsunami Risk

<p>Historical earthquakes in the Java subduction zone have given genesis to tsunami affecting the southwest coasts of the island of Java, in Indonesia. The most recent earthquake on the 17<sup>th</sup> of July 2006, has given rise to a tsunami that killed more than 600 people. The tsunami was difficult to escape due to the small amount of ground shaking, which could have acted as an early warning, and due to the epicentre being very close to the shorelines, giving insufficient time for response. Historical data and scientific studies give little evidence for mega-thrust events in the Java trench, however such possibilities are not excluded and could have a devastating impact in the region. This work aims to assess the tsunami hazard occurring from a range of earthquake scenarios in the subduction zone. Taking as a benchmark the 2006 event, we initially validate our modelling approach against the wave observations recorded at three tide gauges. We then expand our work to account for future earthquake scenarios and their tsunamigenic consequences in the southern coasts of Java island. Bathymetry displacement is computed using the Okada elastic dislocation model. The nonlinear shallow water equation solver JAGURS is employed for the modelling of wave propagation. Our objective is to quantify the uncertainty of such events by using statistical surrogates: fast stochastic approximations of the model that can explore the likelihood of thousands of tsunami scenarios in a few moments of time. Gaussian process emulators are utilised to predict maximum wave amplification occurring from varying parameter distributions such as the moment magnitude of an earthquake. The resulting tsunami hazard footprints can be used in conjunction with existing socio-demographic information to assess tsunami risk in vulnerable areas. The end-data can eventually be used to inform policy making for better disaster mitigation planning.</p>

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Tsunami Hazards Associated with the Catalina Fault in Southern California

Earthquake Spectra ◽

10.1193/1.1773592 ◽

2004 ◽

Vol 20 (3) ◽

pp. 917-950 ◽

Cited By ~ 16

Author(s):

Mark R. Legg ◽

Jose C. Borrero ◽

Costas E. Synolakis

Keyword(s):

Southern California ◽

Initial Conditions ◽

Tsunami Hazard ◽

Return Periods ◽

Tsunami Hazards ◽

Sea Floor ◽

Earthquake Scenarios ◽

Santa Catalina Island

We investigate the tsunami hazard associated with the Catalina Fault offshore of southern California. Realistic faulting parameters are used to match coseismic displacements to existing sea floor topography. Several earthquake scenarios with moment magnitudes ranging between 7.0 and 7.6 are used as initial conditions for tsunami simulations, which predict runup of up to 4 m. Normalizing runup with the maximum uplift identifies areas susceptible to tsunami focusing and amplification. Several harbors and ports in southern California lie in areas where models predict tsunami amplification. Return periods are estimated by dividing the modeled seafloor uplift per event by the observed total uplift of the Santa Catalina Island platform multiplied by the time since the uplift began. The analysis yields return periods between 2,000 to 5,000 years for the Catalina Fault alone, and 200 to 500 years when all offshore faults are considered.

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