The Mount Meron infrasound array: an infrasound array without a noise reduction system

Measurements of seismo-acoustic events by collocated seismic and infrasound arrays allow for studying the two wavefields that were produced by the same event. However, some of the scientific and technical constraints on the building of the two technologies are different and may be contradicting. For the case of a new station, an optimal design that will satisfy the constraints of the two technologies can be found. However, in the case of upgrading an existing array by adding the complementing technology, the situation is different. The site location, the array configuration and physical constraints are fixed and may not be optimal for the complementing technology, which may lead to rejection of the upgrade. The International Monitoring System (IMS) for the verification of the Comprehensive Nuclear-Test-Ban Treaty (CTBT) includes 37 seismic arrays and 51 infrasound arrays. Although the CTBT verification regime is fixed in the treaty, an upgrade of the existing arrays by adding more technologies is possible. The Mount Meron seismic array (MMAI), which is part of the IMS, is composed of 16 sites. Microbarometers were installed at five MMAI sites to form the Mount Meron infrasound array. Due to regulation and physical constraints, it was not possible to relocate the sites nor to install analogue noise reduction filters (i.e. a pipe array). In this study, it is demonstrated that the installation of the MMAI infrasound array is beneficial despite the non-optimal conditions. It is shown that the noise levels of the individual array sites are between the high and median global noise levels. However, we claim that the more indicative measures are the noise levels of the beams of interest, as demonstrated by analysing the microbaroms originated from the Mediterranean Sea. Moreover, the ability to detect events relevant to the CTBT is demonstrated by analysing man-made events during 2011 from the Libya region.