Palaeostress analysis of a giant Holocene rockslide near Boaco and Santa Lucia (Nicaragua, Central America)

Abstract

A giant rockslide occurred on the southern side of an Upper Tertiary shield volcano in central Nicaragua in the Holocene. The failure caused tectonic-like deformation of rock masses and changed the local stress regime. The lower, compressional part of the rockslide produced a stress field with the axis of maximum stress (σ1) parallel to the displacement vector of the main body. The upper part of the rockslide was gravity-driven with σ1 vertical and σ3 horizontal, and oriented SE–NW. The mass tended to move SE. In the crown, the stress field had a subvertical σ1 steeply dipping towards the west. Data at the base of the Santa Lucia Depression, where east- and west-dipping reverse and thrust faults developed, showed that the compressional stress, σ1, was nearly horizontal and east–west oriented, the horizontal σ2 was north–south oriented, and the σ3 was subvertical. These compressional conditions resulted from the collapse of the crown after the main slope failure phase. Simultaneously, along with the gravity relaxation of the main displaced mass, the slopes and mountain slopes along the main scarp depression underwent deep-seated sliding, sagging and flowing.

Volcanic edifice slip events recorded on the fault plane of the San Andrés Landslide, El Hierro, Canary Islands

“…In a volcanic setting it has been found that slow collapse of a Tertiary shield volcano in the Nicaraguan Highlands during the Holocene modified the local palaeostress field and generated normal, reverse, and strike slip faults (Baroň et al, 2011). However, volcanic collapses are somewhat difficult to study because they are comparatively rare events.…”