Long Beach rolls with Ocotillo Temblor as Quakes swarm the Southland
2010-06-14 · By Editor
A 5.7 magnitude earthquake rolled through Southern California tonight startling Long Beach residents. The temblor, centered 5 miles southeast of Ocotillo, was felt in San Diego, Orange and Los Angeles counties.
The quake, which happened June 14, at 9:26 p.m., was followed by more than 45 aftershocks in the first two hours with 19 aftershocks above magnitude 3 and the strongest calculated at magnitude 4.5.
The Ocotillo quake, which was strong enough to knock items off of shelves and break windows, caused a pause in the action at the Blue Jays-Padres game in San Diego’s Petco Park. Residents of Los Angeles County and Long Beach experienced a more gentle wave.
Seismologists say that Monday’s quake —as well as others that have shaken the same area in recent weeks—are aftershocks of April’s 7.2 earthquake.
Earlier today, a series of smaller earthquakes took place in the same area. However, seismologists agree that these events can not be predicted.
Quakes After the Earthquake
According to the U.S. Geological Survey, immediately after the mainshock the probability of a strong and possibly damaging aftershock in the next 7 days is approximately 40 percent. Most likely, the 5.7 magnitude mainshock will be the largest in the sequence.
There is a small chance (approximately 5-10 percent) of an earthquake equal to or larger than this mainshock in the next 7 days.
Aftershocks are most common immediately after the main shock and decrease rapidly as time passes. Aftershocks are most likely to be felt in the first few days, but may be felt weeks, months, or even years afterwards. In general, the larger the mainshock, the longer its aftershocks will be felt.
As a rule of thumb, a magnitude 6 mainshock may have aftershocks up to 10 to 20 miles away, while a magnitude 7 mainshock may have aftershocks as far as 30 to 50 miles away.
Additional Warnings and Alerts
The West Coast/Alaska Tsunami Warning Center responded to the quake with an Information Statement saying that “The magnitude and location are such that a tsunami IS NOT EXPECTED. However, in coastal areas of intense shaking, locally generated tsunamis can be triggered by underwater landslides.” In most cases, information statements are issued to indicate there is no threat of a destructive tsunami and to prevent unnecessary evacuations as the earthquake may have been felt in coastal areas.