Takahito Mikami

• Dr. Eng.
• Professor (Associate) at Waseda University

Manila Trench is an ocean trench that lies to the west of Luzon Island in the Philippines, which has the potential to generate a significant tsunami that could affect the coastal areas around it. This paper analyzes the tsunami hazard at the southern coastline of China, and more specifically at the city of Shantou. A Monte Carlo-type probabilistic...

On January 1st, 2024, a major earthquake near the Noto Peninsula, Japan, triggered tsunami waves that impacted coastal communities in the region. This study reports findings from two field surveys conducted four days and two months after the event to understand the tsunami's mechanisms and effects, respectively. The proximity of the epicenter to la...

The 28th September 2018 Sulawesi Supershear earthquake (MW 7.5) was one of the deadliest earthquakes in the recent history of Indonesia causing ~4000 causalities. The earthquake caused a ~ 177 km long surface rupture along the Palu-Karo fault. Apart from surface rupture, the earthquake caused extensive earthquake environmental effects (EEEs) around...

There is a fear that many coastal communities could be forced to relocate in the face of sea level rise (SLR). However, there is little, if any, evidence of any relocation actually taking place, despite a number of past examples of relative sea level rise (as a result not only of SLR itself, but also earthquake or groundwater extraction induced sub...

Land subsidence has triggered severe coastal floods in Jakarta, whose mechanism has been extensively investigated by researchers and engineers. The government has also recognized this fact, which has partially contributed to the recent announcement that the capital will be relocated to East Kalimantan. However, it is not clear whether ordinary peop...

The September 28, 2018 earthquake and tsunami, which occurred north of Palu City, Indonesia, attracted widespread interest from the scientific community due to the unusually large tsunami that occurred after a strike-slip earthquake with a relatively small moment magnitude (M_W = 7.5). To understand the structural performance of buildings and infra...

On the 22 nd of December 2018 tsunami waves generated by the flank collapse of the Anak Krakatau volcano in Indonesia flooded the shorelines of the nearby Sumatra and Java islands. The authors conducted a field survey of the Krakatau archipelago to clarify the volume of the collapsed flank and the run-up of the tsunami around the islands themselves...

At 21:30 local time (UTC+7h) on the 22nd of December 2018 the shorelines of the Sunda Strait, Indonesia, were flooded by tsunami waves. As a result there was widespread destruction and there were 437 casualties, 31,943 injuries, 10 still missing and over 16,000 people displaced (as of the 14th January 2019 National Disaster Management Agency (BNBP)...

In 2018, Lombok island, Indonesia, was hit by a series of destructive earthquakes that caused thousands of casualties and widespread material damage. In response to those events, a field survey was conducted along the coast of Lombok aiming at collecting data about disaster preparedness and awareness of local inhabitants regarding natural disasters...

Volcanic ashfall can cause considerable social impacts to a wide geographical area. Given the challenge to predict volcanic eruptions, it is essential to simulate the dispersion of ash as soon as possible after an event and promptly estimate the distribution of deposits and necessary removal works. In this study, a series of procedures to improve t...

In the case of a near-field tsunami event, coastal residents must quickly become aware of the potential danger of a tsunami taking place and start taking actions to evacuate. The present paper aims to show which types of evacuation triggers worked amongst coastal residents with different characteristics and backgrounds by conducting a comparative a...

The September 28 2018 Palu tsunami surprised the scientific community, as neither the earthquake magnitude nor its strike-slip mechanism were deemed capable of producing the wave heights that were observed. However, recent research has shown that the earthquake generated several landslides inside Palu bay. The authors conducted a post-disaster fiel...

In 2018 Lombok island, Indonesia, was hit by a series of destructive earthquakes that caused thousands of casualties and widespread material damage. In response to those events a field survey was conducted along the coast of Lombok aiming at collecting data about disaster preparedness and awareness of local inhabitants regarding natural disasters,...

In 2018 Lombok island, Indonesia, was hit by a series of destructive earthquakes that caused thousands of casualties and widespread material damage. In response to those events a field survey was conducted along the coast of Lombok aiming at collecting data about disaster preparedness and awareness of local inhabitants regarding natural disasters,...

Current climate change discourses have expressed fear that many coastal communities would be forced to relocate in the face of rising water levels. However, despite the frequency and intensity with which such messages are being broadcasted throughout the world's media, there is little actual evidence of any relocation actually taking place, even th...

Water–level fluctuations resembling long period waves, which differ from normal wind waves, were observed immediately after the Tohoku earthquake of 2011 in multiple locations, such as lakes in Yamanashi Prefecture, the fjords of Norway, and other sites located far away from the epicenter. Not many research on similar abnormal water–level fluctuati...

The authors conducted extensive field surveys in densely populated coastal areas affected by land subsidence in Indonesia, Philippines and Japan. The results indicate that the preferred adaptation mechanism for coastal areas is elevating them using soil, rubble, or coral stones, and then re-surfacing to obtain a smooth surface, and building dykes w...

On September 28, 2018, a large earthquake and its accompanying tsunami waves caused severe damage to the coastal area of Palu Bay, in the central western part of Sulawesi Island, Indonesia. To clarify the distribution of tsunami inundation and run-up heights, and damage to coastal communities due to the tsunami, the authors conducted a field survey...

Five cases of ports in Japan and Indonesia that have subsided by a metre or more were analysed. The findings suggest that there are no unsurmountable technological, cost-benefit, financial and social limits to the progressive raising of these ports, at least for the magnitude of climate-induced sea-level rise expected during the 21st century. In In...

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 tsuna...

In 2015 and 2017 unusual ocean and atmospheric conditions produced many years’ worth of rainfall in short periods over Northern Chile’s Atacama Desert, resulting in catastrophic flooding in the town of Chañaral. However, the town is not only at risk of fluvial flooding, it is also at risk of tsunamis. Through a community mapping exercise, the autho...

In 2015 and 2017 unusual ocean and atmospheric conditions produced many years’ worth of rainfall in short periods over Northern Chile’s Atacama Desert, resulting in catastrophic flooding in the town of Chañaral. However, the town is not only at risk of fluvial flooding, it is also at risk of tsunamis. Through a community mapping exercise, the autho...

In the past two decades there have been fears that many low-lying atoll islands around the world could disappear as a consequence of climate change and sea level rise, leading to mass migration and threatening the existence of several island nations. Here we show how sea level rise does not inevitably lead to coastal areas becoming uninhabitable, a...

This report presents a wealth of publicly-available information, as well as unique insights generated from the efforts of StEER’s Field Assessment Team (FAT-1) led by Associate Director for Assessment Technologies, Ian Robertson, working in collaboration with a larger international reconnaissance team. The intent of this report is to: 1. provide an...

Extreme coastal events such as the 2004 Indian Ocean Tsunami, the 2011 Tohoku Tsunami as well as the 2005 Katrina and 2012 Sandy hurricanes demonstrated that, hydrodynamic loading aside, debris loading represents a major factor in the extreme loading conditions experienced by inland infrastructure. While extreme hydrodynamic loading due to coastal...

Chañaral is a town located at the mouth of the Salado River in northern Chile (Lat 26.3 °S). The main economic activity in its vicinity is copper mining, such as at Potrerillos and El Salvador. The river mouth is typically closed due to the coastal sediment transport. In addition, a large reclamation area was built from mine tailings and a highway...

According to the Intergovernmental Panel on Climate Change 5th Assessment Report, or IPCC 5AR (2013), sea level is rise (SLR) could be in the order of 26 to 98 cm by 2100. However, more onerous predictions, such as those set forth in recent probabilistic process-based models by Kopp et al. (2017), or Bars et al., (2017), indicate that SLR could be...

If the attempt of stopping land subsidence ends up being successful, future flood issues in Jakarta could be mitigated with a short dyke together with pumps because a coastal flood is triggered by a 20-40 cm extra tide. People who experienced a 2-m flood did not notice the progress of subsidence. Effort for raising awareness of subsidence among lo...

Debris loading during extreme flooding events has been documented by many post-tsunami field surveys of disaster-stricken communities and, as such, it is now considered and accounted for as a critical design consideration in the design of resilient infrastructure. Debris damming is one of the debris loads of concern, occurring when solid objects en...

Sustainability scientists often face a difficult task to conduct research or carry out preliminary investigations around coastal areas in developing countries, due to the limitation in the availability of topographical and bathymetry data. These limitations can be particularly important for the case of ports, on which the livelihoods of many fishin...

This paper compares two different types of storm surge disaster based on field surveys. Two cases: a severe storm surge flood with its height of over 5 m due to Typhoon Haiyan (2013) in Philippine, and inundation of storm surge around Nemuro city in Hokkaido of Japan with its maximum surge height of 2.8 m caused by extra-tropical cyclone are taken...

Water level fluctuations resembling long period tsunami waves, which differ from normal wind waves, were observed immediately after the Great East Japan Earthquake of 2011 in multiple locations, such as lakes in Yamanashi Prefecture, the fjords of Norway, and other sites located far away from the epicenter. Very little research on similar abnormal...

Debris loads during flood events have been well-documented by forensic engineering field surveys of affected communities. Research has primarily focused on debris impact loading and less emphasis has been placed into quantifying the loads and effects associated with debris damming, which occurs when solid objects accumulate at the front of structur...

This paper reports on an experimental test program investigating the motion and entrainment of flow-entrained debris. The motion of debris in large scale hydraulic events can cause severe damage to the impacted communities: the dynamic characteristics of the debris' motion is crucial in identifying high-risk areas in affected communities. Determini...

Sea level rise will pose a significant challenge to coastal settlements throughout the planet and is likely to disproportionately affect poorer communities, which are usually located in particularly vulnerable areas. Coastal areas in Jakarta have been experiencing rapid subsidence in recent years, and could serve to illustrate the likely challenges...

An experimental study was performed to examine multiple debris entrainment and transport in tsunami-like flow conditions. The study was performed in the Tsunami Wave Basin at Waseda University. The wave basin used a falling-head driven elongated solitary wave that broke at the edge of a horizontal apron to generate a tsunami-like surge. The debris,...

The 2011 Tohoku Tsunami caused severe damage in coastal areas. In Kesennuma, oil spilled from oil tanks that was attacked by the tsunami. The present study aims to evaluate the safety of oil tanks against a tsunami and understand the behavior of spilled oil in Tokyo Bay. The results of tsunami numerical simulation with Keicho Earthquake scenario sh...

On 11 March 2011, an exceptionally large tsunami event was triggered by a massive earthquake offshore, the northeast coast of Japan, which affected coastal infrastructure such as seawalls, coastal dikes and breakwaters in the Tohoku region. Such infrastructure was built to protect against the Level 1 tsunamis that previously hit the region, but not...

Jakarta, the capital of Indonesia, is one of the largest coastal megacities in the planet. Although Jakarta has been facing many urban development issues, the issue of land subsidence appears to have become especially serious over the last couple of decades. Recently, Takagi et al. investigated two distinctive mechanisms of coastal floods in Jakart...

In the present paper, to understand keys to successful evacuation during a near-field tsunami event, first triggers for tsunami evacuation were summarized based on the reports of field surveys on four recent tsunami events. Five different types of triggers can be identified: feeling ground motion, seeing other people's behavior / hearing other peop...

This study presents the results of an experimental research program dealing with spatial debris motion on a horizontal apron depicting a typical harbor wharf. Accordingly, scaled-down 6.1-m (20-ft) shipping containers were equipped with a novel yet nonintrusive real-time tracking system and motion sensors. The instrumentation allowed for the spatio...

Flood disasters such as dam breaks and surges from extreme hurricanes or tsunamis entrain and transport substantial amounts of submerged or floating debris. Understanding of motion and spatiotemporal distribution of debris entrained by a flood is thus of great importance to hydraulic, coastal, and structural engineers; the displacement of debris to...

Thin coastal dykes typically found in developing countries may suddenly collapse due to rapid land subsidence, material ageing, sea-level rise, high wave attack, earthquakes, landslides, or a collision with vessels. Such a failure could trigger dam-break tsunami-type flooding, or “dyke-break-induced tsunami”, a possibility which has so far been ove...

Hydraulic laboratory experiments were conducted to ascertain various phenomena observed during recent field surveys of tsunamis and storm surges. Essentially, the nature of tsunami waves appears to be far more complex than the simple experiments that used to be carried out in previous times. Thus, in order to understand the destruction mechanism of...

Thin coastal dykes typically found in developing countries may suddenly collapse due to rapid land subsidence, material aging, sea-level rise, high wave attack or a collision with vessels. Such a failure could trigger a dam-break tsunami-type flood, or dyke-break induced tsunami, a possibility which has so far been overlooked in the field of coasta...

Typhoon Haiyan (Yolanda) struck the islands of Leyte and Samar, the central part of the Philippines, on 8 November 2013, bringing large-scale devastation to coastal areas due to the high winds and large storm surge and waves associated with it. In order to obtain the distribution of storm surge heights and damage covering the wide stretch of affect...

Category 5 Typhoon Haiyan was one of the strongest typhoons to hit the Philippines in modern times, and introduced the term “storm surge” to the vocabulary of many local residents, who had not heard about such phenomena prior to this event. The storm surge manifested itself on the 8th November 2013 as Haiyan made landfall, devastating large areas i...

Sea level rise and an increase in typhoon intensity are two of the expected consequences from future climate change. In the present work, a methodology to change the intensity of tropical cyclones in Japan was developed, which can be used to assess the inundation risk to different areas of the country. As a result, the probability of a storm with a...

The Japanese coastal areas have a lot of different types of coastal structures with different purposes, and it is important to understand each structure's effects on tsunami. In the present paper, the authors focused on detached breakwaters effects on tsunami flow around coastal dykes with a field data investigation and laboratory experiments using...

In recent years, many tsunami disasters have taken place in small remote islands, which can be considered to be particularly vulnerable against coastal disasters. In this chapter the authors discuss how to prepare for future tsunami threats in remote islands based on the results of their own field surveys conducted after two recent tsunami events....

Many coastal dikes in Tohoku area in Japan were damaged due to the 2011 Great Eastern Japan Earthquake Tsunami. The primary failure mode of these dikes was scour failure at the leeward toe by the overflowing tsunami. However, the forces exerted by the tsunami wave against the dikes and scour were reduced to the presence of some obstacles (such as c...

During the 2011 Tohoku Tsunami, there were eyewitness testimonies that tsunami inundation height was reduced due to Teizan-canal along the coast of Sendai Plain. The present study aims to understand the tsunami reduction effect of a canal by using the field data and the results of a laboratory experiment. The field data obtained from the 2011 event...

The low pressure with rapid development generated storm surge and inundation over a port and city in Nemuro. The aims of this paper are to provide the information of storm surge height measured by the authors and to clarify the generation mechanism of the storm surge. Based on the authors' field survey, the maximum storm surge height at the street...

Vietnam, with 3260 km coastline and two vast low-lying deltas (the Red River Delta and Mekong Delta), could be considered one of the most vulnerable countries against coastal disasters and climate change. However, it appears that people outside Vietnam do not notice the vulnerability of this country's coasts against disasters, and even the vast maj...

On October 29, 2012, Hurricane Sandy made landfall along the eastern coast of the United States, generating a storm surge that caused serious damage to New York City and its vicinity. The authors carried out a post storm surge field survey in New York City, including Manhattan and Staten Island, to clarify the distribution of storm surge heights an...

The present chapter describes the characteristics of the massive storm surge generated by the 2013 Typhoon Yolanda (Haiyan), which made landfall on the coast of the Philippines on November 2013. The authors conducted a series of field surveys and numerical analysis in Leyte and Samar Islands in the aftermath of the disaster in order to understand t...

The 2004 Indian Ocean tsunami was the first significant transoceanic tsunami in the digital age, allowing the population of the entire world to witness the destructive power of such phenomena. Despite the fact that such events form part of the culture of countries such as Chile and Japan, many other places had virtually not heard about them before...

On the 11 th of March 2011, an earthquake offshore the northeast coast of Japan generated a huge tsunami which overwhelmed coastal defences and inundated extensive areas of the Tohoku coastline. Japan was considered to be well prepared against such disasters but nevertheless casualties were high, though death rates were not homogeneous within the a...

Coastal dikes, breakwaters and seawalls are generally used to control floods, debris flows, erosion and even massive catastrophic events such as tsunamis. However, these structures will only perform well if they are firmly constructed in terms of strength and stability of slopes and toes and can resist the dynamic forces imposed by the incident wav...

The combined effect of an increase in typhoon intensity and sea level rise could pose significant challenges to coastal defences around Tokyo Bay. In the present chapter the authors determined the storm surge that could result from an increase in typhoon intensity around Tokyo Bay around the turn of the 21 st century. This was then combined with a...

Category 5 Typhoon Haiyan (known as Yolanda in the Philippines) made landfall in the Philippines on the 8 th November 2013 at almost the peak of its power, devastating the islands of Leyte and Samar, amongst other places. The present paper analyses the degree of awareness and preparedness of the islands of Samar and Leyte in the Philippines against...

The Vietnamese coast faces the East Sea, which has been recognized as having the potential to generate devastating tsunamis, thus requiring a careful consideration of tsunami risk. In this chapter, tsunami risk and vulnerability are analyzed based on the numerical simulation of tsunami propagation and the social and geographical background of Vietn...

抄録 The catastrophic typhoon “Yolanda” on Nov. 2013 invoked storm surge in the coastal area of the Philippines. The storm surge made the coastal regions to the devastation and maximum water height reached 5m in the Tacloban area. This paper presents the comparison between storm surge simulated results from atmospheric - storm surge- wave- tide coupl...

The authors have examined the characteristics of Typhoon Haiyan (Yolanda), which made landfall on the coast of the Philippines on November 2013, generating a substantial storm surge. In order to better understand the storm surge phenomenon, its nature and severity were analyzed by means of a numerical simulation and a field survey. Unlike most othe...

In November 2013, Typhoon Yolanda (Haiyan) struck the central part of the Philippines and caused severe damage to coastal areas due to storm surge and strong wind. In this paper, the results of the field survey conducted one month after the disaster were summarized. Storm surge heights were more than 5 m along the inner part of Leyte Gulf, and seve...

Typhoon Yolanda made landfall in Leyte Island at near peak strength, with maximum sustained wind speeds of 160 knots, the largest in the recorded history of the Western North Pacific. Yolanda ap-proached very quickly with a forward speed of 41km/hr towards Leyte, which was also the largest among typhoons with similar intensities. As a result of the...

On October 25, 2010, a large earthquake occurred off the coast of the Mentawai islands in Indonesia, generating a tsunami that caused damage to the coastal area of North Pagai, South Pagai, and Sipora islands. Field surveys were conducted soon after the event by several international survey teams, including the authors’. These surveys clarified the...

The design of breakwater armor units against tsunami attacks has received little attention in the past because of the comparative low frequency of these events and the rarity of structures designed specifically to withstand them. However, field surveys of recent events, such as the 2011 Tohoku Earthquake Tsunami and the Indian Ocean tsunami in 2004...

Many coastal dikes in Iwate, Miyagi and Fukushima prefectures in Japan were damaged due to the 2011 Great Eastern Japan Earthquake Tsunami. The primary failure mode of these dikes was scour failure at the leeward toe by the overflowing tsunami. However, the forces exerted by the tsunami wave against the dikes were reduced to the presence of some ob...

Increases in typhoon intensity and sea level rise could pose significant challenges to coastal defences around Tokyo Bay. In order to analyse the extent of future problems the authors determined the increase storm surge that could result from an increase in typhoon intensity and sea level rise to this area around the turn of the 21st century. Resul...