Field Survey of the 2018 Anak Krakatau Tsunami on the Islands in the Sunda Strait

2020 ◽  
Author(s):  
Hermann M. Fritz ◽  
Tubagus Solihuddin ◽  
Costas E. Synolakis ◽  
Gegar S. Prasetya ◽  
Jose C. Borrero ◽  
...  
Keyword(s):  
Tsunami Source ◽  
Flow Depth ◽  
Community Based Education ◽  
Tsunami Hazards ◽  
Survey Team ◽  
Tsunami Runup ◽  
Awareness Programs ◽  
Education And Awareness ◽  
Krakatau Volcano ◽  
Steep Slopes

<p>On December 22, 2018, an eruption and partial collapse of the Anak Krakatau volcano generated a tsunami in the Sunda Strait. The tsunami caused catastrophic damage and more than 400 deaths in coastal regions of the Sunda Strait in Lampung (Sumatra) and Banten (Java). An international tsunami survey team (ITST) was deployed 6 weeks after the event to document flow depths, runup heights, inundation distances, sediment deposition, impact on the natural environment and infrastructure. The 4 to 9 February 2019 ITST focused on islands in the Sunda Strait: Rakata, Panjang, Sertung, Sebesi and Panaitan. The survey team logged more than 500 km by small boat. The collected survey data includes almost 100 tsunami runup and flow depth measurements. The tsunami impact peaked along steep slopes facing Anak Krakatau with an 85 m runup on Rakata and an 83 m runup on Sertung. The extreme runup heights were within less than 5 km of Anak Krakatau. Flow depth reached more than 11 m above ground on Sertung where a boat landing was possible and trees remained standing. On Sebesi Island located 15 km northeast of the source tsunami runup heights remained below 10 m. In contrast, tsunami heights exceeding 10 m were observed in the Ujung Kulon National Park located 50 km southwest of Anak Krakatau. The runup distributions on the islands encircling Anak Krakatau highlight the directivity of the tsunami source with the Anak Krakatau collapse towards the southwest. Inundation and damage were mostly limited to within 400 m of the shoreline given the relatively short wavelengths of volcanic tsunamis. Significant variation in tsunami impact was observed along shorelines of the Sunda Strait with tsunami heights rapidly decreasing with distance from the point source. Field observations, drone videos, and satellite imagery are presented. The team interviewed numerous eyewitnesses based on established protocol and educated residents about tsunami hazards. The tsunami caught the locals off guard despite the history and a six-month long eruptive activity in the lead up. Community-based education and awareness programs are essential to save lives in locales at risk from locally generated tsunamis. The 500 m initial height difference between the 1883 Krakatau and 2018 Anak Krakatau collapses provides a perspective on these two tsunamis. Remaining and future tsunami hazards will be affected by volcanic edifice regrowth.</p>

Working Condition, Problems and Its Impact on the Health of Sexual and Gender Minorities

2018 ◽  
Vol 21 ◽  
pp. 24-30
Author(s):  
Bishnu Kumar Adhikari
Keyword(s):  
Working Condition ◽  
Sexual Exploitation ◽  
Sexual And Gender Minorities ◽  
Interview Schedule ◽  
Sex Worker ◽  
Descriptive Research ◽  
Gender Minorities ◽  
Awareness Programs ◽  
Education And Awareness ◽  
And Gender

The third gender in contemporary societies is viewed from different angle. They have been facing different problems because of their sexuality. The objective of the paper is to explore the working condition, problems and its impact on the health of sexual and gender minorities in community. The descriptive research design was adopted in this study. It was based on field study in Kathmandu valley. Interview schedule has been applied as tool of data collection. The study was delimited to the LGBTI registered under BDS only. Altogether 100 respondents were selected out of total (111) purposively. Most of the LGBT (53.6%) were involved in private sector and 34.56% were working as sex worker. The respondents (38.47%) reported that they were dismissed from the job and 12.5% suffered from sexual exploitation and rape. Similarly, 32.78% suffered from mental tension and 20% suffered from depression. Social support, information education and awareness programs targeting the LGBT and studies covering a diverse population are recommended.

The Role of Education and Awareness in Tackling Insider Threats

2019 ◽  
pp. 33-52
Author(s):  
Shaun Joseph Smyth ◽  
Kevin Curran ◽  
Nigel McKelvey
Keyword(s):  
Insider Threat ◽  
Insider Threats ◽  
The Future ◽  
Awareness Programs ◽  
Education And Awareness ◽  
Access Data

Insider threats present a major concern for organizations worldwide. As organizations need to provide employees with authority to access data to enable them to complete their daily tasks, they leave themselves open to insider attacks. This chapter looks at those who fall into the category which can be referred to as insiders and highlights the activity of outsourcing which is employed by many organizations and defines the term insider threat while pointing out what differentiates an accidental threat from a malicious threat. The discussion also considers various methods of dealing with insider threats before highlighting the role education and awareness plays in the process, the importance of tailoring awareness programs, and what the future holds for insider threats within organizations.

Raindrop Size and Flow Depth Control Sediment Sorting in Shallow Flows on Steep Slopes

2018 ◽  
Vol 54 (12) ◽  
pp. 9978-9995 ◽  
Author(s):  
L. Wang ◽  
N. F. Fang ◽  
Z. J. Yue ◽  
Z. H. Shi ◽  
L. Hua
Keyword(s):  
Flow Depth ◽  
Control Sediment ◽  
Shallow Flows ◽  
Depth Control ◽  
Sediment Sorting ◽  
Raindrop Size ◽  
Steep Slopes

Engineering lessons from the 28 September 2018 Indonesian tsunami: debris loading

2020 ◽  
Vol 47 (1) ◽  
pp. 1-12 ◽  
Author(s):  
J. Stolle ◽  
C. Krautwald ◽  
I. Robertson ◽  
H. Achiari ◽  
T. Mikami ◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
Local Community ◽  
Field Survey ◽  
Tsunami Wave ◽  
Concrete Structures ◽  
Tsunami Source ◽  
Reinforced Concrete Structures ◽  
Research Gaps ◽  
Survey Team ◽  
Source Mechanisms

A field survey team went to Palu City, Indonesia in the aftermath of the September 28th, 2018 earthquake and tsunami to investigate its effects on local infrastructure and buildings. The study focused on the coast of Palu Bay, where a tsunami wave between approximately 2 and 7 m high impacted the local community as a result of several complex tsunami source mechanisms. The following study outlines the results, focused on loading caused by debris entrained within the inundating flow. Damage to timber buildings along the coast was widespread, though reinforced concrete structures for the most part survived, providing valuable insights into the type of debris loads and their effects on structures. The results of this survey are placed within the context of Canadian tsunami engineering challenges and are compared to the recently-released ASCE 7 Chapter 6 – Tsunami Loads and Effects, detailing potential research gaps and needs.

scholarly journals Field Survey of Tsunami Heights and Runups Following the 22 December 2018 Anak Krakatau Volcano Tsunami, Indonesia

2020 ◽  
Vol 177 (10) ◽  
pp. 4577-4595 ◽  
Author(s):  
Mohammad Heidarzadeh ◽  
Purna Sulastya Putra ◽  
Septriono Hari Nugroho ◽  
Doud Ben Zubair Rashid
Keyword(s):  
Rare Event ◽  
Tsunami Height ◽  
Field Surveys ◽  
Tsunami Runup ◽  
Tsunami Risk ◽  
Western Shore ◽  
Wave Heights ◽  
One Year ◽  
Instrumental Records ◽  
Krakatau Volcano

Abstract The 22 December 2018 Anak Karakatau tsunami in Indonesia was a rare event in that few instrumental records existed of tsunamis generated by volcanic sources before this event. The tsunami, which left a death toll of 437, is of global importance as it provides opportunities to develop knowledge on generation, propagation and coastal effects of volcanic tsunamis. Here, we report results of field surveys along the coast of the Sunda Strait, Indonesia to study tsunami wave heights and coastal damage. We surveyed 29 locations and measured ranges of tsunami runup from 0.9 to 5.2 m, tsunami heights from 1.4 to 6.3 m, flow depths from 0.2 m to 3.0 m and inundation distances from 18 to 212 m. The largest tsunami heights and concentration of damage and fatalities occurred on the western shore of Java from Tanjung Lesung to Sumur. The largest cluster of fatalities occurred at Tanjung Lesung, where more than 50 people died while attending an outdoor music being held at the shoreline. The tsunami runup and tsunami height in Tanjung Lesung were 4.0 and 2.9–3.8 m, respectively. We believe this tragedy could have been avoided if the event organizers were more aware of the hazard posed by the Anak Krakatau volcano, as it had been actively erupting for several months prior to the tsunami, and simply moved the concert stage 100 m inland. Many of the locations surveyed demonstrated a similar pattern where the majority of casualties and destruction occurred within 100 m of the coast; in several locations, lives were saved where buildings were located at least this distance inland. The significant damage and numerous deaths which occurred in Sumur, despite the moderate tsunami height of 2.3–2.5 m, can be attributed to the extremely low-lying coastal land there. Flow depth in Sumur was 0.9–2.0 m. During our field surveys, nearly one year after the event, we noted that some of the damaged buildings were being rebuilt in the same locations just 10–30 m from the shoreline. We question this practice since the new buildings could be at the same tsunami risk as those damaged in the 2018 event.

scholarly journals Impact of a 1755-like tsunami in Huelva, Spain

2010 ◽  
Vol 10 (1) ◽  
pp. 139-148 ◽  
Author(s):  
V. V. Lima ◽  
J. M. Miranda ◽  
M. A. Baptista ◽  
J. Catalão ◽  
M. Gonzalez ◽  
...  
Keyword(s):  
Source Parameters ◽  
Critical Factor ◽  
Maximum Flow ◽  
High Energy ◽  
Tsunami Source ◽  
Flow Depth ◽  
Large Area ◽  
Inundation Extent ◽  
Run Up ◽  
The Impact

Abstract. Coastal areas are highly exposed to natural hazards associated with the sea. In all cases where there is historical evidence for devastating tsunamis, as is the case of the southern coasts of the Iberian Peninsula, there is a need for quantitative hazard tsunami assessment to support spatial planning. Also, local authorities must be able to act towards the population protection in a preemptive way, to inform "what to do" and "where to go" and in an alarm, to make people aware of the incoming danger. With this in mind, we investigated the inundation extent, run-up and water depths, of a 1755-like event on the region of Huelva, located on the Spanish southwestern coast, one of the regions that was affected in the past by several high energy events, as proved by historical documents and sedimentological data. Modelling was made with a slightly modified version of the COMCOT (Cornell Multi-grid Coupled Tsunami Model) code. Sensitivity tests were performed for a single source in order to understand the relevance and influence of the source parameters in the inundation extent and the fundamental impact parameters. We show that a 1755-like event will have a dramatic impact in a large area close to Huelva inundating an area between 82 and 92 km2 and reaching maximum run-up around 5 m. In this sense our results show that small variations on the characteristics of the tsunami source are not too significant for the impact assessment. We show that the maximum flow depth and the maximum run-up increase with the average slip on the source, while the strike of the fault is not a critical factor as Huelva is significantly far away from the potential sources identified up to now. We also show that the maximum flow depth within the inundated area is very dependent on the tidal level, while maximum run-up is less affected, as a consequence of the complex morphology of the area.

Time-dependent Tsunami Source Following the 2018 Anak Krakatau Volcano Eruption Inferred from Nearby Tsunami Recordings

2020 ◽  
Author(s):  
Yifan Zhu ◽  
Chao An ◽  
Teng Wang ◽  
Hua Liu
Keyword(s):  
Source Region ◽  
Time Dependent ◽  
Tsunami Source ◽  
Water Volume ◽  
Generation Process ◽  
Tsunami Generation ◽  
Time Duration ◽  
Initial Water ◽  
Volcano Eruption ◽  
Krakatau Volcano

Abstract The eruption of the Anak Krakatau volcano, Indonesia, on 22 December 2018 induced a destructive tsunami (the Sunda Strait tsunami), which was recorded by four nearby tidal gauges. In this study we invert the tsunami records and recover the tsunami generation process. Two tsunami sources are obtained, a static one of instant initial water elevation and a time-dependent one accounting for the continuous evolution of water height. The time-dependent results are found to reproduce the tsunami recordings more satisfactorily. The complete tsunami generation process lasts approximately 9 min and features a two-stage evolution with similar intensity. Each stage lasts about 3.5 min and elevates a water volume of about 0.15 km 3 . The time, duration and volume of the volcano eruption in general agree with seismic records and geomorphological interpretations. We also test different sizes of the potential source region, which lead to different maximum wave height in the source area, but all the results of time-dependent tsunami sources show the robust feature of two stages of wave generation. Our results imply a time-dependent and complex process of tsunami generation during the volcano eruption.

Development of High Precision Tsunami Runup Calculation Method Based on a Hierarchical Simulation

2016 ◽  
Vol 11 (4) ◽  
pp. 639-646 ◽  
Author(s):  
Taro Arikawa ◽  
◽  
Takashi Tomita ◽  
◽  
Keyword(s):  
High Precision ◽  
Calculation Method ◽  
Fluid Motion ◽  
Three Dimensional ◽  
Tsunami Source ◽  
Tsunami Runup ◽  
Precise Evaluation ◽  
Major Disaster ◽  
The Stability ◽  
Expensive Process

The 2011 Great East Japan Earthquake (GEJE) has shown that tsunami disasters are not limited to inundation damage in a specified region, but may destroy a wide area, causing a major disaster. Evaluating standing land structures and damage to them requires highly precise evaluation of three-dimensional fluid motion – an expensive process. Our research goals were thus to develop a coupling STOC method [1] and CADMAS-SURF/3D [2] to efficiently calculate all stages from tsunami source to runup and to verify their applicability. We confirmed the method’s accuracy by computing in the Onagawa District during the GEJE and comparing results to observed data. We also investigated the stability of buildings.

Field surveys and numerical modeling of the December 2018 Anak Krakatau volcanic tsunami

2020 ◽  
Author(s):  
Mohammad Heidarzadeh ◽  
Purna Sulastya Putra ◽  
Abdul Muhari ◽  
Septriono Hari Nugroho
Keyword(s):  
Numerical Modeling ◽  
Source Model ◽  
Tsunami Source ◽  
Tsunami Height ◽  
Tsunami Inundation ◽  
Field Surveys ◽  
Source Models ◽  
Krakatau Volcano ◽  
Source Dimension ◽  
Maximum Tsunami Height

<p>We report results of field surveys and numerical modeling of the tsunami generated by the Anak Krakatau volcano eruption on 22 December 2018. We conducted two sets of field surveys of the coastal areas destroyed by the Anak Krakatau tsunami in 26-30 December 2018 and 4-10 January 2020. Field surveys provided information about the maximum tsunami height as well as the most damaged area. The maximum tsunami height was up to 13 m. Most locations registered a wave height of 3-4 m. Tsunami inundation was limited to approximately 100 m. For modeling, we considered 12 source models and conducted numerical modeling. The scenarios have source dimensions of 1.5–4 km and initial tsunami amplitudes of 10–200 m. By comparing observed and simulated waveforms, we constrained the tsunami source dimension and initial amplitude in the ranges of 1.5–2.5 km and 100–150 m, respectively. The best source model involves potential energy of 7.14 × 10<sup>13</sup>–1.05 × 10<sup>14</sup> J which is equivalent to an earthquake of magnitude 6.0–6.1.</p>

Tsunami runup on steep slopes: How good linear theory really is

1991 ◽  
Vol 4 (2-3) ◽  
pp. 221-234 ◽  
Author(s):  
Costas Emmanuel Synolakis
Keyword(s):  
Linear Theory ◽  
Good Linear ◽  
Tsunami Runup ◽  
Steep Slopes
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