April 13, 2012
Scientists Gather To Discuss Possibility Of San Diego Quakes
Things could get shaky as scientists will gather in San Diego next week to present their latest seismological research at the annual conference of the Seismological Society of America (SSA).
This year´s conference is expected to have record numbers, as well as a special public town hall meeting which will feature talks on the seismic dangers in San Diego as well as the threat of future earthquakes and tsunamis.
As the city of San Diego sits on top of a fault system, there is a considerable seismic threat to the missions of residents in the area. Working with colleagues from international engineering company URS Corporation, Ivan Wong has evaluated the potential hazards, mentioning the possibilities of “strong ground shaking” as well as “surface faulting” in the downtown area. Additionally, several ruptures could be seen along the Rose Canyon fault system as well as ruptures along the San Diego fault. This surface faulting hazard is low, however, as the rate of activity along this fault is low. The aforementioned ground shaking hazard is probably high, according to Wong, due to the disturbed nature of the Rose Canyon fault system.
This fault system´s behavior as it travels through San Diego isn´t yet widely understood, according to SSA press release. Should a large earthquake occur (somewhere in the magnitude of 7 and up), it is unclear what role the individual faults in the Rose Canyon system will play and how frequently they could produce such a quake.
“It is clear however that the threat to the city from a future large earthquake is considerable and that research is needed to define what that level of hazard is,” said Ivan Wong, principal seismologist and vice president of URS Corporation.
Adding to the potential for significant seismic activity in the San Diego region are the San Jacinto and San Andreas faults.
Geophysicist Tom Rockwell and his San Diego State University colleagues have found the seismically active San Jacinto fault, a major part of the San Andreas Fault system, to be of particular importance to the San Diego area. Rockwell and his team have mapped past earthquakes suggesting evidence of a similar quake along the San Jacinto fault.
In addition to these onshore quakes and land-shaking events, other seismologists have produced maps of active faults off the southern coast of California which could clarify some of the earthquake hazards for the area. Jamie Conrad of the US Geological Survey says these maps could help explain the underwater seismic hazards of this region, as their activity isn´t well understood. According to Conrad, it´s still unclear how these faults interact with one another and how much the faults slip. These new maps cover the offshore faults of the region known as the Inner Continental Borderland, between the coast and the San Clemente fault. Lying among the jagged and crumpled seafloor between Santa Monica and the Mexican border are several faults, running for north to south. Conrad and his ream were able to revise the current map of these faults by using high-resolution seismic reflection data, including multiple sources of sonar beamed from research ships. The new data now shows linkages between faults that were previously unknown to be joined. In addition, the new data also showed cases of fault slipping at a rate of 1-2 millimeters per year.
Such research is becoming all the more pertinent as recent earthquakes shook parts of Oregon and Mexico. Some are even predicting a quake might even strike the San Diego area before these scientists have a chance to convene there.