The Northridge earthquake occurred on January 17, 1994 Pacific a neighborhood in the city of Los Angeles, California, lasting for about 10–20 seconds. The earthquake had a "strong" moment magnitude of 6.7, but the ground acceleration was one of the highest ever instrumentally recorded in an urban area in North America, measuring 1.7 g At least 33 deaths were attributed to the earthquake, with some estimates ranging much higher, and there were over 8,700 injured. In addition, the earthquake caused an estimated $20 billion in damage, making it one of the costliest natural disasters in U.S. history.
The 8.9-magnitude temblor, which was centered near the east coast of Japan, killed hundreds of people, caused the formation of 30-foot walls of water that swept across rice fields, engulfed entire towns, dragged houses onto highways, and tossed cars and boats like toys. Some waves reached six miles inland in Miyagi Prefecture on Japan's east coast.
Seismic waves are waves of energy that travel through the ground, for example as an earthquake, explosion, or some other process that imparts low-frequence of energy. Many other natural and anthropogenic sources create low waves commonly referred to as ambient vibrations.Waves are studied by seismologists and geophysicists. Seismic wavefields are measured by a seismograph, geophone, hydrophone in water .
