Origin of the pulse-like signature of shallow long-period volcano seismicity

Journal of Geophysical Research B: Solid Earth
By:  and 

Links

Abstract

Short-duration, pulse-like long-period (LP) events are a characteristic type of seismicity accompanying eruptive activity at Mount Etna in Italy in 2004 and 2008 and at Turrialba Volcano in Costa Rica and Ubinas Volcano in Peru in 2009. We use the discrete wave number method to compute the free surface response in the near field of a rectangular tensile crack embedded in a homogeneous elastic half space and to gain insights into the origin of the LP pulses. Two source models are considered, including (1) a vertical fluid-driven crack and (2) a unilateral tensile rupture growing at a fixed sub-Rayleigh velocity with constant opening on a vertical crack. We apply cross correlation to the synthetics and data to demonstrate that a fluid-driven crack provides a natural explanation for these data with realistic source sizes and fluid properties. Our modeling points to shallow sources (<1 km depth), whose signatures are representative of the Rayleigh pulse sampled at epicentral distances >∼1 km. While a slow-rupture failure provides another potential model for these events, the synthetics and resulting fits to the data are not optimal in this model compared to a fluid-driven source. We infer that pulse-like LP signatures are parts of the continuum of responses produced by shallow fluid-driven sources in volcanoes.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Origin of the pulse-like signature of shallow long-period volcano seismicity
Series title Journal of Geophysical Research B: Solid Earth
DOI 10.1002/2016JB013152
Volume 121
Issue 8
Year Published 2016
Language English
Publisher American Geophysical Union
Contributing office(s) Volcano Science Center
Description 11 p.
First page 5931
Last page 5941