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Swarm of earthquakes rattles southern California

swarm-earthquakes-rattled-southern-california

More than 210 earthquakes hit the state of California on Sunday with the strongest measuring 5.5. The earthquakes were felt as far away as San Diego, Temecula, and San Clemente. The first quake occurred about three miles northwest of Brawley, and registered as magnitude 3.8. It was followed by a swarm of quakes in the same area, according to the U.S. Geological Survey.

The earthquakes are occurring on a northeast striking fault zone located about 6 km north of the northwest end of the mapped Imperial Valley fault. This is within the area called the Brawley Seismic Zone. The BSZ extends from the northern end of the Imperial fault to the southern end of the San Andreas Fault. It has been characterized by swarms that have occurred in the 1930s, the 1960s, and 1970s.  The last significant swarm before this one occurred in 2005 along the south shore of the Salton Sea, with the largest event of M5.1. In 1981 there was swarm-like activity called the Westmoreland sequence, with the largest event of M 5.8, which occurred 8 km to the northwest of today’s activity.  Some of the aftershocks of the Mw6.4 1979 earthquake occurred in the same general area.

In the 1960s and 1970s, the southern part of the BSZ was very active. Several swarms included many thousands of events but with the largest magnitude of only M5.0 or less. From 1981 to 2000, the Brawley Seismic Zone was quiet. In the last decade, several swarms smaller than today’s were recorded in the northern part of the zone.

Click here for a list of all related swarm events.

Faults of Southern California – SCEC

The magnitude 5.3 quake occurred at 19:31:22 UTC with an epicenter at a depth of 12.3 km (7.6 miles), located 5 km (3 miles) NNW of Brawley. It was felt in Moreno Valley, Indio, National City and Palm Desert, even in Yuma, Arizona and Mexico. USGS PAGER issued Yellow alert for economic damage for Brawley and Westmorland.

It was followed by M4.9, M3.4, M2.6, and M4.3 in a period of just 10 minutes.

A magnitude 5.5 earthquake occurred at 20:57:58 UTC at a depth of 9 km (5.6 miles),  located 5 km (3 miles) NNW (347°) from Brawley. There were reports of minor damage to old buildings in Bradley’s downtown where most of the earthquakes occurred. No injuries had been reported.

Expected future development of this activity

In the past, these types of swarms have continued for many days.  Previously, events of up to M6.2 have occurred on northeast striking cross faults, but bigger events are possible on the major northwest striking late Quaternary faults in this vicinity according to the Southern California Seismic Network (SCSN).

However, according to Thomas Jordan, director of the USC-based Southern California Earthquake Center, it is something not unusual for the southern edge of the San Andreas Fault, which has seen similar occurrences in recent years. This swarm could continue to rumble the region for a few days, Jordan added. Seismologists are always concerned where there is significant seismic activity because that means there is a higher probability of having more seismic activity.

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6 Comments

  1. Add: E. Tsiapas 2012 paper says MOHO is pyrosphere. Perhaps there are substantial gas accumulations in the MOHO and if the pressure gets high enough could they go off like dominoes? And be represented by this ‘earthquake swarm?”

  2. I agree sun is capable of disturbance but is reflection of planetary distubances. Perhaps there is a disturber of the entire system? If the heliosphere is being compressed and NASA admits it is, then what energy is outside our heliosphere doing the compressing?
    It seems that it is periodic, and releases suddenly per myth since that is all we have to go on so far.
    There is interesting research with holes and electrons which have the ability to first expand then compress. Remember that disappearing dust ring? Well, what if that is an example of expansion then compression? Is the disappearance of our compression going to coincide with the sun’s shaking off the old magnetic field? Is there going to be a compression wave generated?

  3. The cycles are strong with this swarm as the Earth shudders with plate adjustments, as one can tell a lot of energy will be stored up and released in the coming days. What part of the planet I don’t know?

    It’s patterns are obvious within the “ring of fire” as if the Earth and Sun are communicating with each other via magnetic portals and plasma every few minutes. The portals have been detected by NASA and other agencies to add clarity.

    Now, let’s look at it this way, the Sun has the ability to disturb the Earth and other planetary objects with its energy, but what has the ability to affect other objects and perhaps agitate the Sun in the process yet benefit from its energy outside of our solar system?

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