Understanding the Lorca, Spain May 11 2011 earthquake

Last update: May 12, 2011 at 9:09 pm by By

The southeastern Spain earthquake of 11 May, 2011, occurred within the plate boundary region that separates the Eurasia and Africa (Nubia) plates. At the longitude of the earthquake, the Africa plate moves NW with respect to the Eurasia plate with a velocity of 6 mm/yr.

Earthquakes in different parts of the plate-boundary region separating Africa and Eurasia may occur as the result of strike-slip or normal faulting, in addition to the reverse/thrust faulting that is expected as the most direct consequence of the convergence of two major plates. The diversity of faulting styles over the plate-boundary region may reflect the motions of crustal blocks that are situated within the broader plate-boundary zone and that move slowly relative to one another to accommodate the NW/SE convergence of the major plates.

EMSC picture of the faulting origin

The epicenter of the 11 May earthquake is situated near a major fault, the Alhama de Murcia fault. However, significant field work in the epicentral region of the earthquake will be necessary to confidently determine if the earthquake occurred on a segment of the Alhama de Murcia fault or on a nearby fault.

In recent decades, the larger shallow-focus shocks of southeastern Spain have had magnitudes of about 5.
Shocks of this size occurred near the epicenter of the 11 May earthquake in February 1999 and August 2002. The distributions of damage associated with several shocks that occurred before the twentieth century imply that these shocks had magnitudes in the 6.5-7 range.

Iberia and the Mahgreb also experience occasional deep-focus earthquakes of magnitude greater than 6 that occur at depths of over 600 km in lithosphere that was subducted along the plate boundary millions of years ago.

Seismicity (quake occurence) Map of Spain

 

Some text and pictures: courtesy USGS and EMSC

Comments

  1. I live not too far away from Lorca in the Murcia province, but didn’t feel a thing or know anything about the earthquake until I started receiving text messages and phone calls to see if I was okay from friends and family. I huge shock really this is, we seem to get the odd wobble every now and then but nothing compared to this, my thoughts are with all of the people in Lorca right now.

    • elena sarrión says:

      All my prayer with my brothers and sisters of Spain.. I have a family relative in Spain, in Barcelona, but at the time of the earthquake, I didn’t know where it was, until I saw the news. I live in New York, and I know exactly what it is to be an a situation like that one. In Peru, where I am from, we have earthquakes a lot, specially in winter. The last one that I experienced was in october of 1974, at 7:30 am. and it was the most scarry moment of my life. The earth shake for about one minute and something, and the only thing I could do was cry. I was 6 years old, since that moment, I am traumatized about quakes. I think, that this is the moment that we should be all together helping one to another, no matter where are you from or what language you speak, in times like this, we become one.

      God Bless Lorca, God Bless Spain.

      Elena
      elena_sarrion@hotmail.com

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