Garden-to-gaia, urban sustainability, disasters 321or minutes. Utility lines rupture, houses fall, mid-rise buildings collapse, high-
ways give way, buildings sink, fires break out, and landslides occur. Damage from
San Francisco’s earthquake was mainly because the water pipes broke and a huge
fire swept across the city. The long narrow city of Kobe was Japan’s busiest sea-
port and one of Asia’s top ports. Its earthquake killed 6400 people outright, left
300 000 homeless, crumbled downtown skyscrapers, toppled elevated highways,
and destroyed large parts of the port and city. A 2006National Geographicworld
map suggests that a third of the 38 cities analyzed lies in an earthquake ‘‘high
risk” zone. Overall the two primary strategies in earthquake hazard reduction
are: (1) identifying areas of high seismic risk, and (2) designing structures to
withstand shaking. Progress in both of these has occurred in a few countries.
Tsunami
Earthquakes, as well as underwater volcanic eruptions and landslides,
often trigger seismic waves or tsunamis that race across the ocean at some
500 km/hr (300 mi/hr). Upon reaching shallow water by coastlines, the powerful
wavesswell to great heights and rush inland threatening coastal cities. In 365 AD
an earthquake leveled one of the world’s ‘‘wonders,” the Pharos (Lighthouse)
of Alexandria (Egypt), and sent a tsunami across the Eastern Mediterranean.
Maintaining protective coastal wetlands (Farber 1987, Danielsenet al.2005) and
mainly building at higher elevations are key coastal guards against tsunami
damage.
Flood
In addition to tsumanis, four types of flooding devastate cities. The New
Orleans case introduced above had a perched lake/reservoir at a higher eleva-
tion, so the city was flooded when the levee/dam broke (Costanzaet al.2006).
Second, cities alongside rivers or on river deltas are inundated by water from
upriver (Figure12.1). Deforestation or development on hill slopes and mountain
slopes removes the absorptive capacity of natural vegetation, and accelerates
waterflows overtheland surface into streams and rivers (Chapter4)(Jared 2004).
More water arrives faster, causing a higher peak flow or flood. Third, a coastal
city is subject to flooding, especially during high tides, when huge windstorms
push seawater toward a coastline, effectively raising the water level and inun-
dating onshore areas. The fourth case is a riverside city a short distance inland
from the coast, where the severe onshore windstorm pushes water right up the
river to inundate the city. Thus Bangkok (Color Figure5)gets flooded by water
from both directions, approaching from upriver and approaching from the coast
downriver. Cities partly built on low areas (Amsterdam, Cairo, Dhaka) of course
are especially subject to floods.