StEER releases EARR on December 2019 to January 2020 Earthquake Sequence in Puerto Rico

The Structural Extreme Events Reconnaissance (StEER) Network has released its Preliminary Virtual Reconnaissance Report (PVRR) summarizing its findings on the impacts of the earthquakes in Puerto Rico. The report was prepared by StEER’s Virtual Assessment StEER has released its Early Access Reconnaissance Report for the December 2019 to January 2020 Earthquake Sequence in Puerto Rico, based on the work of our Field Assessment Structural Team (FAST) led by Eduardo Miranda of Stanford University. This FAST was co-sponsored by the John A. Blume Earthquake Engineering Center at Stanford University:

Miranda, Eduardo; Archbold, Jorge; Heresi, Pablo; Messina, Armando; Rosa, Isamar; Robertson, Ian; Mosalam, Khalid; Kijewski-Correa, Tracy; Prevatt, David; Roueche, David(2020) “StEER - Puerto Rico Earthquake Sequence December 2019 to January 2020: Field Assessment Structural Team (FAST) Early Access Reconnaissance Report (EARR).” DesignSafe-CI.

We wish to commend the team and particularly its leader, Eduardo Miranda, for not only mobilizing so quickly for this event, but also for the exceptionally detailed report.

A sequence of earthquakes occurred in the southwestern region of Puerto Rico, initiating at the end of 2019. The first widely-felt earthquake occurred on December 28th, 2019 with a Mw 5.0 magnitude. This was followed on January 6th, 2020 by a much stronger event (Mw 5.8 magnitude), that was felt throughout the island and caused damage to a wide variety of structures in the southwest region of the island. The main event occurred on January 7th, 2020 at 8km S of Indios at 4:24am local time (8:24 UTC) with a magnitude Mw 6.4, followed by thousands of aftershocks. The three largest aftershocks happened on January 7th, 2020 at 8km S of Tallaboa (Mw 5.6 magnitude), on January 7th, 2020 at 9km S of Tallaboa (Mw 5.6 magnitude), and on January 11th, 2020 at 13km S of Guánica at 8:54am local time (12:54 UTC) with Mw 5.9 magnitude.The ground shaking from the earthquakes damaged over 10,000 structures, including the complete collapse of at least 80 structures, most of which were single-family residential units. In addition, several bridges, roads and other infrastructure were also damaged or destroyed and two thirds of the island lost power as a result of the Mw 6.4 earthquake on January 7th. This Early Access Reconnaissance Report (EARR) is StEER’s second product for this event. It provides an overview of the sequence of earthquakes and preliminary findings based on the data and observations generated by the Field Assessment Structural Team (FAST). The FAST documented the performance of 60 structures located in six different cities along the southwestern coast of Puerto Rico between the cities of Ponce and Mayagüez.

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