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Threats to the Blue Economy
Published in Ranadhir Mukhopadhyay, Victor J. Loveson, Sridhar D. Iyer, P.K. Sudarsan, Blue Economy of the Indian Ocean, 2020
Ranadhir Mukhopadhyay, Victor J. Loveson, Sridhar D. Iyer, P.K. Sudarsan
On the west coast also, several earthquakes occurred following the subduction of the Arabian Plate beneath the continental Eurasian Plate. This compression is what formed the Zagros Mountains, which stretched for over 1,500 km from Turkey to Baluchistan through Iran. Located only 100 km off the south coast of Pakistan, the seismic activities near the Makran Trench led to the earliest known tsunami, which is dated to be during the fifteenth century (Regard et al., 2010) followed by two major earthquakes in the recent past. On November 27, 1945, a 8.0 strong earthquake coupled with tsunami occurred along the Makran Trench that killed 4,000 people in Pakistan, while a weaker earthquake of 6.3 intensity occurred on February 8, 2017 but there was no casualty (David Jacobson, February 8, 2017, United States Geological Survey, personal communication). An increase in awareness and better coordination between the littoral states are needed to enhance the capability to manage earthquake impact and also of the early tsunami warning system.
Epilogue: Resilience Engineering Precepts
Published in Erik Hollnagel, David D. Woods, Nancy Leveson, Resilience Engineering, 2017
Erik Hollnagel, David D. Woods
This example illustrates a system that was not resilient, despite being able to detect the risk in time. While precautions had been made and procedures put in place, there was no awareness of whether they actually worked and no understanding of what the actual conditions are. The specific shortcoming was one of communication, issuing inconsistent warnings and lacking feedback, and the consequence was a partial lack of readiness to respond. Using the terminology proposed in Chapter 21, the communication failure meant that some districts did not go into the required state of high alert, as a preparation for an evacuation. While the tsunami warning system was designed to look for specific factors in the environment, it was not designed to look at itself, to ensure that the ‘internal’ functions worked. The system was designed to be safe by means of all the technology and procedures that were put in place, but it was not designed to be resilient.
Marine action and control
Published in F.G. Bell, Geological Hazards, 1999
The Pacific Tsunami Warning System (PTWS) is a communications network covering the countries bordering the Pacific Ocean and is designed to give advance warning of dangerous tsunamis (Dohler, 1988). The system uses 69 seismic stations and 65 tide stations in major harbours around the Pacific Ocean. Earthquakes with a magnitude of 6.5 or over cause alarms to sound and those over 7.5 give rise to around-the-clock tsunami watch. Nevertheless, it is difficult to predict the size of waves that will be generated and to avoid false alarms. Clearly, the PTWS cannot provide a warning of an impending tsunami to those areas that are very close to the earthquake epicentre that is responsible for the generation of the tsunami. In fact, 99% of the deaths and much of the damage due to tsunamis occur within 400 km of the area where it was generated. Considering the speed of travel of a tsunami wave, the warning afforded in such instances is less than 30 minutes. Recently, however, a system has been developed whereby an accelerometer transmits a signal, via a satellite over the eastern Pacific Ocean, to computers when an earthquake of magnitude 7 or more occurs within 100 km of the coast. The computers decode the signal, cause water-level sensors to start monitoring and transmit messages to those responsible for carrying out evacuation plans. On the other hand, waves generated off the coast of Japan take 10 hours to reach Hawaii. In such instances, the PTWS can provide a few hours for evacuation to take place if it appears that it is necessary (Bernard, 1991).
Near-real time tsunami inundation forecast for Central America : case study of the 1992 Nicaragua tsunami earthquake
Published in Coastal Engineering Journal, 2020
Yuichiro Tanioka, Ulbert Gleb Grillo, Greyving Jose Arguello
In 1992, a large earthquake occurred off the Pacific coast of Nicaragua and generated a large tsunami causing significant damage along the Nicaragua coast (Abe et al. 1993). The tsunami was much larger than that expected from its surface wave magnitude of Ms 7.2. Therefore, the earthquake is classified as a “tsunami earthquake” (Satake et al. 1993). After the 1992 Nicaragua tsunami earthquake, a seismic network and the National Tsunami Warning System (NTWS) was developed in Nicaragua (Strauch et al. 2018). However, real-time tsunami forecasts using the surface wave magnitude still have a possibility to underestimate tsunami heights for tsunami earthquakes such as the 1992 Nicaragua earthquake. In 2016, the Central American Tsunami Advisory Center (CATAC) was established at the Nicaraguan Institute of Territorial Studies in Nicaragua with Japanese cooperation. This center should be completed in 2019 (Strauch et al. 2018). It is important to develop a real-time tsunami forecast method that could forecast tsunamis from tsunami earthquakes such as the 1992 Nicaragua earthquake.
NOAA’s national water level observation network (NWLON)
Published in Journal of Operational Oceanography, 2019
A final recent improvement relates to adapting the NWLON to collect 1-minute water level data for enhanced tsunami detection and warning systems. CO-OPS has been involved with tsunami detection and warning for coastal hazard mitigation since the Coast and Geodetic Survey started the Tsunami Warning System in 1948 to provide warnings to the Hawaiian Islands. However, after the 2004 Indian Ocean earthquake and tsunami, CO-OPS upgraded its instrumentation with new hardware (specifically data collection platforms) and software to increase the rate of data collection and transmission at all coastal NWLON stations. A number of new NWLON stations were also established in tsunami prone areas including the Caribbean, U.S. West Coast, and throughout the Pacific. These stations now have the capability to collect high resolution, 1-minute water level data, available to the Tsunami Warning Centers via satellite transmission and CO-OPS 1-minute water level data application. It allows external customers to view the 6-minute and 1-minute data numerically or graphically for all tsunami-capable tide stations in increments of up to four days.
Field survey and evacuation behaviour during the 2018 Sunda Strait tsunami
Published in Coastal Engineering Journal, 2019
Tomoyuki Takabatake, Tomoya Shibayama, Miguel Esteban, Hendra Achiari, Nanda Nurisman, Mustarakh Gelfi, Trika Agnestasia Tarigan, Elsa Rizkiya Kencana, Muhammad Aldhiansyah Rifqi Fauzi, Satriyo Panalaran, Anisa Shafiyya Harnantyari, Thit Oo Kyaw
In addition to the physical survey a questionnaire survey was carried out to assess residents’ perception of danger and evacuation behaviour. Based on the results, while awareness regarding tsunamis is relatively high, it is clear that a tsunami warning system in Sunda Strait would be necessary to minimize the loss of life in the event of a future volcanically generated tsunami. Another important finding was that many residents felt difficulty while evacuating (with many reporting severe congestion in the streets). This is an important issue to address from the point of view of disaster risk management, as if a modern warning system is installed in the future, people could still fail to evacuate due to congestion. Thus, it is imperative to formulate an appropriate evacuation plan so that residents can swiftly evacuate, attempting to minimize road congestion.