Learning from Earthquakes - Earthquake Engineering for Structural Design - page 80

Figure 3.7 Amplification of ground motions in Mexico City due to soft soil
and valley effect (Gioncu and Mazzolani, 2002)

given an important contribution on the very high amplification of records
in the Kobe earthquake, where the magnitude of source was moderate, but
the recorded ground motions in densely erected areas were very high.
Many debates arose after the erection of Taipei 101 Building, due to the
increasing trend of the number and the values of magnitude of ground
motions that occurred under the building site.
The engineering aspects of earthquakes refer to the lessons intended to present
the seismological observations at the level to be used for building design practice.
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Focal depth has a considerable influence on the earthquake characteristics.
Surface sources have influence on a reduced area around an epicenter (see
Californian and Anatolian earthquakes), while the deep sources affect a
large area (for instance Michoacan and Vrancea earthquakes), producing
large damage at locations situated far from the epicenter (see Chapter 1).

- Rupture areas, characterized by length and width, directly influence

earthquake magnitudes and durations.

- Ground motions in near fault zones are characterized by directivity, as a

function of the direction of the fault rupture (in many cases very important
surface displacements along the fault are observed, Figure 3.8). It is very