Aftermath of The Kobe Earthquake

As a powerful 7.1 magnitude earthquake on Sunday jolted many parts of Pakistan, here’s video, which has gone viral on social media, of the infamous Kobe earthquake tragedy which had hit the major port city of Japan situated in the west of Osaka Bay on January 17, 1995.As per the clipping, instruments in a lab in the western part of Japan picked up an intense electromagnetic radiation.

It was the signature of a massive earthquake which had just struck the city of Kobe from its epicenter 20 kms to the south-west.The early morning of the said date, quake had hit Kobe when much of the city was still asleep, trapping many people inside their homes and other buildings.It killed 6,434 people and levelled much of the city, forcing the quake-prone nation to conduct major upgrades of its disaster preparedness.

In addition to those killed, as per reports, 40,000 people were injured and 640,000 buildings were damaged, including over 100,000 homes that were completely destroyed. As many as 310,000 people were forced to find emergency shelter.

The distribution characteristics of collapse ratios of buildings in Kobe city due to the 1995 M7.2 Hyogo-ken Nanbu, Japan (Kobe) earthquake and the interferences due to SH or P-SV and the second surface waves propagating in heterogeneous medium are discussed in this paper by using numerical simulation technique of wave equation. The staggered grid real value fast Fourier transform differentiation (SGRFFTD) is used in the pseudospectral method of ground motion simulations because of its speed, high stability and accuracy. The results show that the maximum amplitude of simulated acceleration wave-forms on the ground coincides well with the complicated distributions of collapse ratios of buildings.

The peak collapse ratio of buildings away from the earthquake fault also coincides well with the peak ground acceleration. The spatial interference process is analyzed by using the snap shots of seismic wave propagation. The peak ground acceleration is probably caused by the interferences due to the second surface wave transmitting from the bedrock to sedimentary basin and the upward body wave. Analyses of the interference process show that seismic velocity structure and geologic structure strongly influence the distribution of the maximum amplitude of acceleration waveforms.

Interferences occurring near the basin boundary are probably the cause of the peak collapse ratio of buildings away from the fault. Therefore it is necessary to analyze wave propagations and interference process using numerical simulation strategy for studies on the seismic disasters.