Monitoring aseismic tectonic processes via hydrologic responses: An analysis of log-periodic fluid flow events at the Costa Rica outer rise

Abstract

A log-periodic series of fluid inflow events from the outer rise off the Nicoya Peninsula, Costa Rica, was recorded on a flow meter deployed at the sediment surface. Similar periodic series have been seen in many failure processes in laboratory and field research, including seismic and chemical records preceding earthquakes. Each cycle has the appearance of an impulse and subsequent decay. The hypothesis that the recorded flow pattern is a result of a series of relatively small strain events resulting from aseismic extensional faulting of the outer rise basement is explored, and analytical results supporting this hypothesis are presented.