The pattern of energy release during the Imperial Valley, California, earthquake of 1940 is studied by analyzing the El Centro strong motion seismograph record and records from the Tinemaha seismograph station, 546 km from the epicenter. The earthquake was a multiple event sequence with at least 4 events recorded at El Centro in the first 25 seconds, followed by 9 events recorded in the next 5 ...

construction of asphaltic core dams is a relatively novel method especially in iran. iran is located in a region with high seismicity risk. therefore, many researchers have focused on the behavior of such types of dams under earthquake loading. in this research, the behavior of asphaltic core rockfill dams (acrd) has been studied under earthquake loading using nonlinear dynamic analysis method ...

We extend the notion of waiting times for a point process to recurrent events in space-time. Earthquake B is a recurrence of a previous one, A, if no intervening earthquake happens after A and before B in the spatial disc centered on A with radius AB. The cascade of recurrent events, where each later recurrence to an event is closer in space than all previous ones, forms a sequence of records. ...

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We have developed a method to detect long-period precursors for large earthquakes observed in southern California, if they occur. The method allows us to continuously monitor seismic energy radiation over a wide frequency band to investigate slow deformation in the crust (e.g., slow earthquakes), especially before large earthquakes. We used the long-period records (1 sample/sec) from TERRAscope...

The excavation in the Wanfung area has provided evidence for at least three earthquake ruptures, including the 1999 ChiChi one. The Chi-Chi earthquake formed an obviously major reverse fault, backthrust, and several minor normal faults, accompanied by a teardrop-shape anticline in the fault tip. Paleoseismic ruptures I and II show the vertical displacement of 0.4 m and 1.2 m, respectively, whic...

The seismoscope is a simple instrument designed originally to give a largely qualitative indication of the strong ground motions produced by an earthquake. It consists of a smoked watch glass attached to a two-degree-of-freedom pendulum with a period of 1⁄4 sec and damping about 10 per cent of critical; a pen records the pendulum motions on the watch glass. One point on the displacement spectru...

Most instruments used in seismological practice to record ground motion are pendulum seismographs, velocigraphs, or accelerographs. In most cases it is assumed that seismic instruments are only sensitive to the translational motion of the instrument’s base. In this study the full equation of pendulum motion, including the inputs of rotations and tilts, is considered. It is shown that tilting th...

Computing displacement from measured acceleration is important for understanding the characteristics of an earthquake. However, to obtain such displacement with a good accuracy is difficult. It is partly because the low-frequency component dominating the behavior of the displacement is often affected by the sensor’s tilt and the measurement error. To avoid these, a high pass filter is usually a...