A new method for Seismic Site Characterization-Los Angeles‘shaken by biggest quake in years’

A 4.7-MAGNITUDE earthquake shook buildings in Los Angeles today, with US seismologists saying it was the strongest to hit the area since 2010, but there were no reports of damage or casualties.

The epicentre of the quake was some 19 kilometres southeast of Anza, California – about 100 miles southeast of Los Angeles – and was felt in San Diego, two hours’ drive down the coast from LA.

The quake shook buildings including one housing AFP’s offices in Hollywood, northwest of downtown. But there were no immediate reports of people being hurt or property being damaged, according to the Los Angeles Times or other media.

The USGS initially put the magnitude of the quake at 5.1, but later downgraded it to 4.7. It was still the strongest quake in the LA metropolis since since 2010.

“It’s been three years since we had anything this size this close to Los Angeles,” said USGS seismologist Susan Hough.

Los Angeles is on the so-called “Ring of Fire”, which circles the Pacific and has produced a number of devastating earthquakes, including Japan’s March 2011 quake and tsunami, which killed thousands of people.

You may be doubt that what is the character of the earthquake location?Recommend an article from SCIRP 《An Improved Method for Seismic Site Characterization with Emphasis on Liquefaction Phenomena》. In this paper, nonlinear geotechnical seismic hazard analysis considering the local site effects was executed and the soil lique-faction potential analysis has been evaluated for the Nemat Abad earth dam in Hamedan province of Iran because of its important socioeconomic interest and its location. Liquefaction susceptibility mapping is carried out using a decisional flow chart for evaluation of earthquake-induced effects, based on available data such as geological, groundwater depth, seismotectonic, sedimentary features, in situ, field and laboratory geotechnical parameters. A series model tests were conducted and then on base of the achieved data the idealized soil profile constructed. A C# GUI computer code “NLGSS_Shahri” was Generate, developed and then employed to evaluate the variation of shear modulus and damping ratio with shear strain amplitude to assess their effects on site response. To verify and validate the methodology, the obtained results of the generated code were compared to several known applicable procedures. It showed that computed output of this code has good and suitable agreement with other known applicable procedures.