Site response assessment at the city of Al Khobar, eastern Saudi Arabia, from microtremor and borehole data
, M. Alharbi1 . 2015
Abstract Al Khobar City is affected by distant earthquakes
from the Zagros fold-fault belt, which is part of the subduction
zone between the Arabian and Eurasian plates. These earthquakes
have generated substantial site effects on the sedimentary
layers, which in turn significantly influence earthquake
ground motions in the area. Mapping of site response using
microtremor measurements compared with geological and
borehole data from Al Khobar City is the main objective of
this work. The resonance frequency and the corresponding
horizontal-to-vertical (H/V) ratio values have been calculated
using the Nakamura technique on data from seismograph instruments
deployed at 113 sites in Al Khobar City for different
time periods. The recording length was about 1 h with a sampling
frequency of 100 Hz. Most of the measured sites present
three peaks of resonance frequency; the first peak ranges from
0.33 to 1.03 Hz, the second peak ranges from 1.03 to 1.23 Hz,
while the third one ranges from 1.23 to 1.73 Hz. Tests have
been conducted to ensure that these peaks are of natural origin
The northern zones of Al Khobar City have lower resonance
frequency values, indicating great sediment thickness. In contrast,
the southern parts of the city have higher resonance
frequency values, suggesting shallow bedrock depths.
Furthermore, 29 geotechnical boreholes have been drilled to
different depths in Al Khobar City
حاولنا قدر الاستطاعة في هذا الكتاب أن ننقل للقارئ العربي أحدث
ما في المراجع العالمية من جديد في مجال الشعاب المرجانية. ولقد حاولنا أيض ً ا أن
نوضح ما نريد بالأشكال التوضيحية والصور…