EXPERIMENT SHOWS QUAKE TENDENCIES.Byline: Robert Monroe Staff Writer SYLMAR - Preliminary data from an October seismic experiment suggests that areas immediately north of Granada Hills and near the Los Angeles River The Los Angeles River is an intermittent river flowing through Los Angeles County, California, from Canoga Park in the west end of the San Fernando Valley, 51 miles (82 km) southeast to its mouth in Long Beach. might shake more in an earthquake than other parts of the San Fernando Valley San Fernando Valley Valley, southern California, U.S. Northwest of central Los Angeles, the valley is bounded by the San Gabriel, Santa Susana, and Santa Monica mountains and the Simi Hills. , a researcher said Thursday. Sound waves generated by a string of explosions set off by a team of geophysicists revealed a deep sedimentary basin The term sedimentary basin is used to refer to any geographical feature exhibiting subsidence and consequent infilling by sedimentation. As the sediments are buried, they are subjected to increasing pressure and begin the process of lithification. south of Mission Point, where the Valley and the San Gabriel Mountains San Gabriel Mountains, S Calif., E and NE of Los Angeles, running c.50 mi (80 km) westward from Cajon Pass. San Antonio Peak (10,080 ft/3,072 m) is the highest of the range. Citrus fruits are raised on the southern foothills. meet. U.S. Geological Survey The term geological survey can be used to describe both the conduct of a survey for geological purposes and an institution holding geological information. A geological survey geophysicist Gary Fuis said the Los Angeles Los Angeles (lôs ăn`jələs, lŏs, ăn`jəlēz'), city (1990 pop. 3,485,398), seat of Los Angeles co., S Calif.; inc. 1850. region seismic experiment that he headed will produce a clear picture of the Valley underground within a few months. ``We have a wonderful data set that we think will produce images that are going to be a real help.'' Fuis said. Fuis delivered his remarks to a group of about two dozen at Mission College. The experiment featured underground explosions detonated at sites throughout the Valley in mid-October. From readings taken during the explosions, scientists hoped to gather data about how the earth moves when it quakes. Sound waves generated by the explosions travel faster through firm earth and more slowly through sedimentary rock sedimentary rock: see rock; sediment. sedimentary rock Rock formed at or near the Earth's surface by the accumulation and lithification of fragments of preexisting rocks or by precipitation from solution at normal surface temperatures. near the surface. Likewise, earthquake shock waves travel more slowly through sedimentary rock, causing greater shaking as the energy seeks release. Fuis said he was amazed that sound waves from Valley explosions were recorded by sensors as far as 80 miles away despite the street noise researchers thought would blur results. Ultimately, the experiment's architects hope to provide detailed maps of area faults and the foundation for better building codes. Preliminary images are expected by this summer at the earliest. Other earthquake researchers were excited by what the team's work appeared to reveal. ``It's overdue,'' said Mission College geography Professor Lorraine Manoogian. ``We need this.'' The session was co-hosted by Mission College's Natural Science Department. |
|
||||||||||||
Printer friendly
Cite/link
Email
Feedback
Reader Opinion