The Chira Quake of 2022

What does it happen underneath the nearby soil of Sullana Metropolitan Area?

 

By Nelson Peñaherrera Castillo | Blog | Twitter | Instagram | WhatsApp

 

 

MIGUEL CHECA, peru – Nothing unusual underneath the soil of Chira Valley but a huge land mass embedding under another apparently static. That’s how the report by Hernando Tavera and Julio Martínez with Peru’s Geophysical Institute (IGP as its initials in Spanish) might be briefed after the 6.1-magnitude quake (moderate) that shook a 155-mile area around a hypocenter 21 miles under a spot 11 miles to the west of Sullana 20101, on October 5^th, 2022.

 

The epicenter was located between the towns of Sojo and Jíbito, Miguel Checa District, that means between Sullana 20771 and Sullana 20770. This fact is relevant for the scientists because it trembled amid the continent, not under the sea, like it indeed has happened in events with magnitudes upper than 7.5, mostly reported at Peruvian Southern as 2001 in Arequipa, or 2007 in Íca.

 

Upon this report and bulletins provided by IGP, within 15 months, the seismicity seems to concentrate practically between Districts Miguel Checa and Marcavelica, almost under Sullana Metropolitan Area.

 

 

Did you get out to the street too?

On October 5th, 2022, 3:26 PET (0826 UTC), the shake was felt as strong in the metropolitan areas of Sullana and Piura as well as the urban zones of Paita and Colán. This gives us a 31-mile radius, approximately, and it covers the whole Chira Valley as well as San Lorenzo and Middle Piura.

 

According to IGP, the sensation that the seismic wave generated on the soil, or intensity, was ranked as VI (of XII) what, in practical terms, means it was felt by everyone who fell in fear and looked for protection (mostly getting out to the streets), had difficulty to walk or hold on, while some dishes and glasses broke, certain heavy furniture moved some inches, and masonry in houses brought down – however, the damages in general were mild.

 

After that event, 26 aftermaths, or reset movements weaker than the initial one, were registered. From them, only four were perceived by the people between 4:00 and 9:00 PET (0900 and 1400 UTC). The magnitudes were in the range between 3.8 and 4.0 (weak).

 

 

Subduction and acceleration

IGP compared the data of this event to another previous on July 30^th, 2021, with same magnitude, intensity, and epicenter, although a hypocenter 0.6 miles deeper.

 

The cause is the subduction or embedding that Nazca Plate works under South-American Plate, around 3 inches per year. The report recognizes this is the origin of similar events broken out in this part of South America. In fact, it’s belief this process formed the Andean Range during last 120 million years.

 

Another fact that broke from comparing both events is the acceleration, or the response of human buildings related to the soil movement, it was about 40% lower in 2022 than 2021. According to IGP, the maximum record for Piura City is 86 cm/s², the lower range was 52 cm/s²: “Those values would explain the fact of having not produced structural damages similar to those presented after the quake happened on July 30^th, 2021.”

 

The seismic acceleration is relevant for the construction industry because it determines how much damage can suffer any structure, “but it also must take in consideration the type of soil where the building is based upon,” civil engineer Jesús Rodríguez lloclla explains to FACTORTIERRA, “because if we talk about a solid soil, this will cushion the seismic waves.”

 

“It’s all the opposite with a light soil,” Rodríguez adds reminding all those parameters are already in the National Code of Buildings.

 

The acceleration in general is calculated when it’s divided the speed (that results from dividing the distance between the time) between the time. The seismic acceleration readings were taken by stations in Sencico facility, Piura 20001, and the local facility of Peru’s Engineers Academy, Piura 20009. The approximate distance between both stations is 2.2 miles, according to GPS surveillance asked by FACTORTIERRA.

 

 

Is it concerning?

For IGP, the hypocenter of October 5^th, 2022 event  is superficial due to its depth. If those data are compared to the existent seismicity at Peruvian Northern, it might say that the parameters are inside the expected, that there’s nothing out of usual.

 

Of course, this could sound distressing to a person without a training to deal with a quake, but it’s actually relevant for urban and road planners.

 

After the October 5th, 2022 event, IGP asked two or three folks in every urban area around the epicenter, it determined that, adding the scare, buildings made of mudbricks experienced cracks, there were slides along Sullana-Paita Road that doesn’t run over a flat surface despite enlarging through Lower Chira Valley, but it goes down and up the Paita Coastal Plateau.

 

Another civil engineer asked by FACTORTIERRA opined that the relevant of this information is how much it could improve the quake warning. IGP has no comments about but it already reported it finished the tests of its SASPe project, and it must integrate now to the new multi-hazard warning system managed by Peru’s National System of Civil Defense which it’s estimated to be available in 2023.

 

At the moment, quakes can’t be predicted or forecast but if there’s a previous shaking history, it must be considered that an event may happen anytime. Up to then, prevention Will be the better response for avoiding everything ends to be a disaster or a catastrophe.

 

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