Field Response and Surface-Rupture Characteristics of the 2020 M 6.5 Monte Cristo Range Earthquake, Central Walker Lane, Nevada

The M 6.5 Monte Cristo Range earthquake that occurred in the central Walker Lane on 15 May 2020 was the largest earthquake in Nevada in 66 yr and resulted in a multidis-ciplinary scientific field response. The earthquake was the result of left-lateral slip along largely unmapped parts of the Candelaria fault, one of a series of east?northeast-strik-ing faults that comprise the Mina deflection, a major right step in the north?northwest structural grain of the central Walker Lane. We describe the characteristics of the sur-face rupture and document distinct differences in the style and orientation of fractures produced along the 28 km long rupture zone. Along the western part of the rupture, left-lateral and extensional displacements occurred along northeasterly and north-strik-ing planes that splay off the eastern termination of the mapped Candelaria fault. To the east, extensional and right-lateral displacements occurred along predominantly north-striking planes that project toward well-defined Quaternary and bedrock faults. Although, the largest left-lateral displacement observed was similar to 20 cm, the majority of displacements were < 5 cm and were distributed across broad zones up to 800 m wide, which are not likely to be preserved in the geologic record. The complex pattern of sur-face rupture is consistent with a network of faults defined in the shallow subsurface by aftershock seismicity and suggests that slip partitioning between east-striking left-lat-eral faults and north to northwest-striking right-lateral faults plays an important role in accommodating northwest-directed transtension in the central Walker Lane.

Automated summary

The M 6.5 Monte Cristo Range earthquake in the central Walker Lane on 15 May 2020 was the largest earthquake in Nevada in 66 years, leading to a multidisciplinary scientific field response. The earthquake was caused by left-lateral slip along unmapped sections of the Candelaria fault, resulting in distinct differences in fracture style and orientation along the 28 km rupture zone. The complex surface rupture pattern suggests that slip partitioning between east-striking left-lateral faults and north to northwest-striking right-lateral faults plays a crucial role in accommodating northwest-directed transtension in the central Walker Lane.