Journal of The School of Marine Science and Technology,Vol.5 No.2
An integration technique for ground displacement from acceleration
records and its application to actual earthquake records
Yoshimi OHTA and Omer AYDAN
Abstract
There are various procedures for evaluating ground velocity and ground displacement from acceleration records.
Although the derivation of velocity and acceleration from displacement records do not present any problem, the
integration of acceleration records to obtain velocity and displacement responses may yield responses different from
the actual ones.Some base-line procedures are used to handle these problems with the concept that the ground would
return to its original position after ground shaking stops. Depending upon the intensity of shaking or crustal
deformations, ground may move permanently, which may invalidate the basic assumption of base-line procedures.
It is well known that every accelerometer is triggered when a threshold value of acceleration or velocity is exceeded.
Furthermore, the accelerometers may induce motions different that from the actual ground motions due to their
inherent physical features.Therefore,the Erratic Pattern Screening (EPS)method proposed by the authors is slightly
modified to obtain the permanent ground displacement with the consideration of features associated with strong
motion recording.This method is applied to results of laboratory faulting and shaking table tests,in which shaking
was recorded using both accelerometers and laser displacement transducers. Furthermore, the method was applied
to strong motion records of several large earthquakes with measurements of ground movements by GPS. The
comparison of computed responses with actual recordings were almost the same,implying that the proposed method
can be used to obtain actual recoverable as well as permanent ground motions from acceleration recordings.