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Bathymetry: Features and Hypsography
Published in Yeqiao Wang, Coastal and Marine Environments, 2020
Heidi M. Dierssen, Albert E. Theberge
The bathymetry of each of the five ocean basins varies considerably (Figure 18.4). Ridges and rises associated with seafloor spreading can be found in all five of the ocean basins. As mapped in the 1800s,[1] the Mid-Atlantic Ridge extends from the north of Iceland to the Southern Ocean boundary. Wide continental shelves (<200 m depth) are visible along much of the western Atlantic Ocean. The vast Pacific Ocean contains mostly broad expanses of deep ocean floor including abyssal hills, chains of seamounts, and lineal scars of great fracture zones. Prominent bathymetric features also occur along the margins of the Pacific Ocean. The Pacific Ocean is bounded by the “Ring of Fire” consisting primarily of subducting plates on the western, northern, and eastern margins with deep trenches and considerable earthquakes and volcanic activity. The southern boundary is defined by the Pacific–Antarctic Ridge and the southern portion of the East Pacific Rise. The Indian Ocean is crossed by ridges and volcanic island structures where the African, Indian, Australian, and Antarctic crustal plates all converge. With the exception of Western Australia, the Indian Ocean has limited continental shelf area. In contrast, the Arctic Ocean represents the shallowest of ocean basins and is characterized by broad expansive deep (500 m) shelves and shallow seas. The Southern Ocean also contains deep continental shelves (500 m), large expanses of abyssal plains, and prominent ridge features bordering the Pacific, Atlantic, and Indian Oceans.
Emerging Diseases
Published in Gary S. Moore, Kathleen A. Bell, Living with the Earth, 2018
Gary S. Moore, Kathleen A. Bell
The Pacific Ocean warming events influence weather patterns and jet streams across North and South America, Western Europe, Asia, and Africa. El Niño events normally begin in the latter part of December and determine weather patterns for a year. The El Niño warming events have historically occurred about twice every 10 years.44 These sea warming events cause evaporation of water, producing extensive rainfall in some areas and drought in others. The power of the El Niño events have increased dramatically in recent years, producing +2°C to 3°C temperature increases in the ocean well into the summer months, and with the possibility of extending over much longer periods of time. It is predicted that El Niño events will be more frequent with greater intensity, onset, and duration consistent with a continued increase in greenhouse gases.45 A warmer climate initiated by increased amounts of carbon in the atmosphere has caused El Niño events to last longer and to be more dramatic.46 The sudden eruption of hantavirus infection in the southwestern United States in 1993–1994, killing 48 percent of the 94 persons infected, has been attributed to the sudden population explosion of deer mice, which harbor the organism. The probable events are that heavy rains fell following 6 years of drought, causing pine nuts and grasshoppers to flourish, which fed the population eruption of deer mice. This enlarged population was driven from the flooded burrows, increasing the possibility of contact with people.47
Physics of the Globe
Published in Aurèle Parriaux, Geology, 2018
An abrupt rise of the ocean bottom can cause a very rapid wave called a tsunami (“wave in the port” in Japanese) (Fig. 4.33a). The Pacific Ocean is the more often affected by tsunamis because of the circum-Pacific subduction zone that causes numerous high magnitude earthquakes. The Kamchatka peninsula, Japan and the Hawaiian Islands are particularly affected by this phenomenon. On December 26, 2004, the Indian Ocean was affected by a tsunami as a result of a 9.0 magnitude earthquake (Fig. 4.33b) The wave reached a velocity of 800 km/hr in the open sea and spread devastation along the neighboring coasts of Indonesia, Thailand, India and Sri Lanka, and even as far as Africa, more than 5000 km from the epicenter of the earthquake. Because of its low amplitude and its long wavelength, the wave was almost undetectable by boats in the open sea. As the wave approached the coasts, the shallows exerted a significant frictional force on the wave. As the wave was slowed down, its height increased spectacularly as it reached the shore. Because of its high kinetic energy, it was able to penetrate several kilometers into the interior of the land in areas of low relief. It killed at least 285,000 people. The death toll could have been much lower if there had been an observation and warning network.
Flood risk assessment data access and equity in Metro Vancouver
Published in Canadian Water Resources Journal / Revue canadienne des ressources hydriques, 2022
Chris Gouett-Hanna, Greg Oulahen, Daniel Henstra, Jason Thistlethwaite
Metro Vancouver was selected as the study location because it contains many local municipalities, allowing for comparison of open data access, and it is exposed to three types of flood hazards. Previous research on flood risk and social vulnerability has been conducted in the study area which this study could draw from and build on (Andrey and Jones 2008; Oulahen et al. 2015; Fraser Basin Council 2020). The region is at risk of coastal flooding due to the proximity of the Pacific Ocean, which sometimes inundates low-lying areas along the shore, and from tsunamis that could be caused by shifting of nearby tectonic plates. Fluvial flooding is an ongoing concern in Metro Vancouver, with the most prominent threat coming from the Fraser River, which runs through the study area and empties into the Pacific Ocean. Finally, Metro Vancouver receives a notable volume of precipitation, which creates an inherent risk of pluvial flooding. This risk is exacerbated by the landscape and soil composition of certain parts of Metro Vancouver, such as the Fraser River delta, which consists of flat plains with poorly drained, sandy, and clay-rich soils (Bertrand, Hughes-Games, and Nikkel 1991). The Metro Vancouver population is socially and economically diverse. For instance, 49% of residents identified as a visible minority in the 2016 census (Statistics Canada 2017). Low-income residents comprise 16.5% of the Metro Vancouver population, which exceeds the national average by 2%. The region’s population is expanding, with growth of 20% since 2001 (Statistics Canada 2017).
Modeling surface waves and tide–surge interactions leading to enhanced total water levels in a macrotidal bay
Published in Coastal Engineering Journal, 2022
Cody McLaughlin, Brent Law, Ryan Mulligan
Earth’s warming climate over the past several decades has yielded an environment favorable for larger, more intense tropical cyclones (Bender et al. 2010). Elevated water levels from storm surge during these intense weather events can lead to catastrophic flooding of coastal regions (Irish, Resio, and Ratcliff 2008) and causes significant damage to infrastructure, especially in low-lying coastal settlements (Baradaranshoraka et al. 2017) due to the difficulty in predicting storm surge. For example, Hurricane Ike (2008) made landfall in Texas with a maximum storm surge height of 5.4 m while Hurricane Katrina (2005) caused a maximum storm surge of 10 m along the Mississippi River (Fritz et al. 2007; Rego and Chunyan 2010b). Both storms resulted in high death tolls and billions of dollars in damage. Hurricane storm surges can also significantly impact wetland bays. For example, Hope et al. (2013) led to detrimental sediment erosion and transport within the Terrebonne and Barrataria Bay along the Gulf of Mexico coast (Liu et al. 2018). Similarly, tropical cyclones that form over the eastern Pacific Ocean, known as typhoons, have significant effects on coastal shores. Typhoon Haiyan (2013) made landfall in the Philippines and produced a storm surge that was amplified to 5 m in the Leyte Gulf and San Pablo Bay that caused an estimated US $802 M in damage (Mori et al. 2014).