Near-field tsunami hazard map Padang, West Sumatra: Utilizing high resolution geospatial data and reseasonable source scenarios

Near-field tsunami propagation both in shallow water environments and bore-like wave propagation on land are conducted in this study to obtain fundamental knowledge on the tsunami hazard potential in the city of Padang, Western Sumatra, Republic of Indonesia. As the region proves a huge seismic moment deficit which has progressively accumulated since the last recorded major earthquakes in 1797 and 1833, this investigation focuses on most reasonable seismic sources and possibly triggered near-shore tsunamis in order to develop upgraded disaster mitigations programs in this densely-populated urban agglomeration located on the western shore of Sumatra Island. Observations from continuous Global Positioning Satellite (cGPS) systems and supplementary coral growth studies confirm a much greater probability of occurrence that a major earthquake and subsequent tsunami are likely to strike the region in the near future. Newly surveyed and processed sets of geodata have been collected and used to progress most plausible rupture scenarios to approximate the extent and magnitudes of a further earthquake. Based upon this novel understanding, the present analysis applies two hydronumerical codes to simulate most probable tsunami run-up and subsequent inundations in the city of Padang in very fine resolution. Run-up heights and flow-depths are determined stemming from these most plausible rupture scenarios. Evaluation of outcome and performance of both numerical tools regarding impacts of surge flow and bore-like wave fronts encountering the coast and inundating the city are thoroughly carried out. Results are discussed not only for further scientific purposes, i.e. benchmark tests, but also to disseminate main findings to responsible authorities in Padang with the objective to distribute the most probable dataset of plausible tsunami inundations as well as to address valuable insights and knowledge for effective counter measures, i.e. evacuation routes and shelter building. Following evacuation simulations based on rational assumptions and simplifications reveal a most alerting result as about 265.000 people are living in the highly exposed potential tsunami inundation area in the city of Padang of which more than 95.000 people will need more than 30 min. to evacuate to safe areas.DFGBMB

Tsunami evacuation plans for future megathrust earthquakes in Padang, Indonesia, considering stochastic earthquake scenarios

This study develops tsunami evacuation plans in Padang, Indonesia, using a stochastic tsunami simulation method. The stochastic results are based on multiple earthquake scenarios for different magnitudes (Mw 8.5, 8.75, and 9.0) that reflect asperity characteristics of the 1797 historical event in the same region. The generation of the earthquake scenarios involves probabilistic models of earthquake source parameters and stochastic synthesis of earthquake slip distributions. In total, 300 source models are generated to produce comprehensive tsunami evacuation plans in Padang. The tsunami hazard assessment results show that Padang may face significant tsunamis causing the maximum tsunami inundation height and depth of 15 and 10 m, respectively. A comprehensive tsunami evacuation plan – including horizontal evacuation area maps, assessment of temporary shelters considering the impact due to ground shaking and tsunami, and integrated horizontal–vertical evacuation time maps – has been developed based on the stochastic tsunami simulation results. The developed evacuation plans highlight that comprehensive mitigation policies can be produced from the stochastic tsunami simulation for future tsunamigenic events

Modelling of the Bengkulu Minor Tsunami Event, September 12, 2007, West of Sumatra, Indonesia

Earthquake magnitude of Mw 7.9 Mw 8.4 was shocking Province of Bengkulu in West Sumatera, Indonesia on September 12, 2007, as reported by BMG-Indonesia, USGS, and GFZ-Potsdam.This paper is our research documentation which is our modelling results as our quick response to Bengkulu earthquake based on a preliminary estimation of earthquake magnitude (Mw. 8.4) and epicentre (101.00°E, 3.78°S) provided by USGS.We employ TUNAMI-N1 model to our domain model which has grid resolutions 1,852 meters, for two scenarios (Mw 8.4 and Mw 8.2) along 4 hours simulation with time step 1 second. Bathymetry data with 1 minute-arc resolution is derived from GEBCO. We also used water level data derived from real time tide gauge data at stations Padang (IODE-VLIZ,2007), Cocos Island (UHSLC, 2007), and DART Buoy No. 23401 (NOAA, 2007) for sea surface wave verification.Our modelling results show tsunami wave propagate from its source location then mainly hit Bengkulu and its surroundings, also minor part of Padang. Maximum wave height in Bengkulu and surroundings were varying between 0.5 meters and 5.3 meters.In general, tsunami wave between modelling results and observations data has similar form, but theres slightly lag of arrival time and differences in wave-form. The best fit of our results is at Padang stations, and then nearly fit at Cocos Islands, which both of them is scenario 1 with earthquake Mw. 8.4. at DART buoy station, from both scenarios, tsunami wave frommodelling results in DART and Cocos station is earlier than observations data.If we compare to the preliminary field survey results of Jose Borrero et al (2007), the maximum wave height in Lais is similar (4.2 meters), but slightly overestimates in Muara Maras and, while slightly underestimates in Tais and Pasar Seluma

People exposure and land use damage estimation caused by tsunami using numerical modelling and GIS approaches (Case study: South Coast of Java - Indonesia)

For tsunami risk analysis information about thenumber of exposed people and about the land-use inthe endangered areas are important inputparameters. Data on people distribution could helpto manage the evacuation planning and mitigate thepeople loss by tsunami. Land-use and potentialdamages are relevant for rehabilitation managementThe aim of the paper is to presentmethodologies and tools to generate the abovementioned missing information before a disasterhappens. Based on this, governmental authoritiescan prepare and calculate how many people areliving in the affected area, how many people couldbe evacuated, and how to perform adequate landuse planning to mitigate the disaster impact. For thedisaster response phase, the local government willbe supported to plan and manage the evacuationprocess more efficiently. For the recovery phase,government will be provided by estimates on theamount and type of potential damages.This research analyzes the estimation of peopleat risk and potential land-use damage estimation bytsunamis in the South Coast of Java, Indonesia.Combinations of numerical modelling andGeographic Information System (GIS) approacheshave been applied in this research. There are threescenarios for tsunami simulations generated byearthquake magnitude Mw 8.5 with differentlocations of the epicentres.TUNAMI-N1 model has been applied todetermine the tsunami wave height in the coastalarea. Validation of tsunami modelling has beenperformed using Aceh Tsunami 2004 data.Inundation modelling was applied to the studyarea and the results were combined with the peopledistribution map and land-use data to estimatepeople at risk and land-use damage by tsunami.People distribution maps during day time andnight time were derived.The results of this research will be integrated inan information system, which in future can beapplied on the level of the local government tobetter mitigate the impact of tsunami disaster andprovide tools for an improved tsunami riskassessment for decision makers at the local level

A probabilistic tsunami hazard assessment for Indonesia

Probabilistic hazard assessments are a fundamental tool for assessing the threats posed by hazards to communities and are important for underpinning evidence-based decision-making regarding risk mitigation activities. Indonesia has been the focus of intense tsunami risk mitigation efforts following the 2004 Indian Ocean tsunami, but this has been largely concentrated on the Sunda Arc with little attention to other tsunami prone areas of the country such as eastern Indonesia. We present the first nationally consistent probabilistic tsunami hazard assessment (PTHA) for Indonesia. This assessment produces time-independent forecasts of tsunami hazards at the coast using data from tsunami generated by local, regional and distant earthquake sources. The methodology is based on the established monte carlo approach to probabilistic seismic hazard assessment (PSHA) and has been adapted to tsunami. We account for sources of epistemic and aleatory uncertainty in the analysis through the use of logic trees and sampling probability density functions. For short return periods (100 years) the highest tsunami hazard is the west coast of Sumatra, south coast of Java and the north coast of Papua. For longer return periods (500–2500 years), the tsunami hazard is highest along the Sunda Arc, reflecting the larger maximum magnitudes. The annual probability of experiencing a tsunami with a height of > 0.5 m at the coast is greater than 10% for Sumatra, Java, the Sunda islands (Bali, Lombok, Flores, Sumba) and north Papua. The annual probability of experiencing a tsunami with a height of > 3.0 m, which would cause significant inundation and fatalities, is 1–10% in Sumatra, Java, Bali, Lombok and north Papua, and 0.1–1% for north Sulawesi, Seram and Flores. The results of this national-scale hazard assessment provide evidence for disaster managers to prioritise regions for risk mitigation activities and/or more detailed hazard or risk assessment

The September 28th, 2018, Tsunami In Palu-Sulawesi, Indonesia: A Post-Event Field Survey

On September 28th, 2018, a powerful earthquake (M-w 7.5) struck the Island of Sulawesi in Indonesia. The earthquake was followed by a destructive and deadly tsunami that hit the Bay of Palu. A UNESCO international tsunami survey team responded to the disaster and surveyed 125km of coastline along the Palu Bay up to the earthquake epicentre region. The team performed 78 tsunami runup and inundation height measurements throughout the surveyed coastline. Measured values reached 9.1m for the runup height and 8.7m for the inundation height, both at Benteng village. The survey team also identified ten large coastal sectors that collapsed into the sea of Palu Bay after the earthquake. The distribution of the measured tsunami data within Palu Bay exhibits a clear localised impact suggesting the contribution of secondary non-seismic local sources to the generation of the tsunami. Findings of the field reconnaissance are discussed to provide an insight into the remaining debated source of the Palu tsunami