6.9 quake near Mexicali felt in L.A, San Diego; no tsunami alert issued

A earthquake first reported at 6.9 and later at 7.2 that hit near Mexicali has rocked all of Southern California, and set high rise buildings in Los Angeles and San Diego rocking back and forth. It hit at 3:40 and was followed by at least one aftershock about 3:55.

Preliminary USGS information indicated the epicenter was 19 miles

southeast of Mexicali, at an area that has been rocking with magnitude 3.0 quakes all week.

While no major damage has been reported on the U.S. side of the border, this could go down as the strongest earthquake to strike so close to San Diego County, topping a 7.1 that struck in Imperial County in 1940. A 6.5 shaker hit near Borrego Springs in 1968.

No major damage was immediately reported in the city of San Diego, Sgt. Ramona Hastings of the San Diego Police Department said.

However, San Diego firefighters found damage to a wall at an old

building at 4133 Kansas St., a fire dispatcher said. The building was taped off, and a building engineer was called.

The dispatcher said firefighters have been responding to ringing alarms and elevator rescues, and several downtown hotel guests hyperventilated.

A 15-year-old boy in Chula Vista hurt his head when he fell down stairs while trying to escape his house in the 2100 block of Bluewater Lane, the dispatcher said.

There were no initial damage reports in the county area either,

according to Lt. Scott Ybarrondo of the Sheriff’s Department and Capt. Nick Schuler of Cal Fire.

The quake struck during a children’s play at the Lemon Grove Lutheran

Church, sending parishioners scurrying for the door, according to an attendee.

Excited San Diegans swarmed Facebook to share their experiences about

the quake. Reports of strong shaking that lasted nearly a minute came from areas as diverse as downtown San Diego, Scripps Ranch and Pauma Valley.

Some calls via cell phones did not connect, though the reason was unclear.

The NOAA West Coast tsunami center’s Web site reported “A strong earthquake has occurred, but a tsunami IS NOT expected along the California, Oregon, Washington, British Columbia, or Alaska coast. NO tsunami warning, watch or advisory is in effect for these areas.

“Based on the earthquake magnitude and historic tsunami records, a damaging tsunami IS NOT expected along the California, Oregon, Washington, British Columbia, and Alaska coasts. Some of these areas may experience non-damaging sea level changes. At coastal locations which have experienced strong ground shaking, local tsunamis are possible due to underwater landslides.”

The epicenter for the quakes was under a small volcanic caldera that

last erupted about 10,000 years ago, located about 20 miles southeast of the border crossing between Calexico and Mexicali. The caldera, which is home to a large geothermal power plant, has been delivering small-to-moderate quakes for the past several months.

The largest recent quake -- before today’s big one -- hit Saturday just after 4 p.m. and was estimated at magnitude 4.3. Its epicenter was about 30 miles southeast of Calexico and 100 miles east of Tijuana, according to the U.S. Geological Survey.

The swarm is centered near Guadalupe Victoria, a small farming town 19

miles southeast of Mexicali. A small volcano there erupted about 10,000 years ago, and geologists say the quake swarm emanates from shallow magma fields associated with tectonic forces that are steadily separating Baja California from the rest of North America.