We Should Keep an Eye - Nazca Plate Waking Up ?

3 earthquakes in less than 3 hours. 5, 4.4 and 4.8 degrees. Besides the Nazca Plate, lots of volcanoes around. Really don't have too much time to follow it now but I count with you ATSers.



Translation:

Three earthquakes occurred this afternoon in Ica (Peru) in less than three hours, according to the Geophysical Institute of Peru (IGP). The earthquakes alarmed to the settlers of Ica and Pisco, that came out of their homes.

The first earthquake, magnitude 5 degrees, was recorded at 2:03 p.m. 81 kilometers southwest of the city of Ica. According to the IGP, the earthquake had a depth of 35 km and an intensity of level III-IV.

The second movement, of 4.4 degrees, took place at 3:22 p.m. 76 kilometers to the southwest of the city of Ica.

The third, of 4.8 degrees, took place at 4:45 p.m., 86 kilometers southwest of Ica.

The depth of the second and third earthquake was 27 and 25 km respectively. The local authorities have not reported damage caused by tremors.

elcomercio.pe...

a reply to: Trueman

Are the second and third movements aftershocks of the first, and therefore do they constitute separate quakes, or are they considered part of the larger whole?

Also, does a single day of activity constitute reason to be concerned that the plate is, as you say "waking up"?

Would it not be more reasonable to watch and see what the fine measurements over the proceeding days tell us? As I understand it, probabilistics plays a large part in any examination of a quake prone areas likelihood of being beset by a significant movement.

Sounds to me like tremors or precursors rather than the actual quake(s), although if these are the precursors, then the actual quake would be about what they have been waiting on in CA.

a reply to: TrueBrit


Good question. We will find out one way or the other.

a reply to: Trueman
The question about waking up implies it went to sleep, did it?

The Nazca plate is moving about 75mm a year versus the South American plate and that movement hasn't stopped, so from that perspective it never sleeps and that movement continually builds up stress. If you look at this map of seismicity in that region from 1900-2007 I think the same basic patterns will continue for the foreseeable future, though we can't predict when the big ones will hit exactly, but we know where they've been in the past and how much stress has likely built up since then.

Poster of the Seismicity of the Nazca Plate and South America