The 30-year-old former Mexico international had yet to feature for Chivas in Liga MX in the 2020 Clausura and will be looking for more playing time at the Earthquakes, where he is united with Argentine head coach Matias Almeyda.
"Oswaldo is a player that can add a lot from the human element as well as in football," said Almeyda. "I had the chance to coach him for two and half years and his position is where we have the fewest players. My hope is that he shows the same level he showed when I coached him previously."
The Michoacan native made his debut in Mexico's first division for Estudiantes Tecos, before moving on to Santos Laguna in May 2012.
Alanis is expected to join the Earthquakes who are in Cancun at preseason training.
"It's tough, I don't think any player likes [not to play], you want to have the possibility of playing, so we'll move forward," Alanistold reporters after undergoing a medical in Guadalajara on Monday. "I'm looking to play, looking to help, that's most important."
Alanis signed for Chivas in 2015, winning a Liga MX title and the CONCACAF Champions League as part of Almeyda's squad, before he transferred to Spain's Getafe in May 2018.
But Alanis' contract was rescinded by Getafe that same summer and in August 2018 he signed for Real Oviedo in Spain's second division, where he played for a year before rejoining Chivas.
The left-footed center-back has played 23 times for Mexico and narrowly missed out on making the 2018 World Cup in Russia.
The Earthquakes kick off their 2020 MLS season at home to Toronto on Feb. 29.
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