High Activity Earthquake Swarm Event Monitoring and Impact Analysis on Underground High Energy Physics Research Facilities

Abstract

A seismic swarm is a series of earthquakes that occur in a small area over a short period of time. A sequence of earthquakes of this magnitude is unusual in Switzerland, and it is impossible to anticipate how it may unfold in the future. The seismic activity of such an event usually fades after a few days or weeks. Significantly greater earthquakes are likely to occur during the next several days, with up to a chance of 5 to 10%. For these reasons, the underground research facilities need tools to provide data on the impact of these events on their experiments. The paper presents the techniques implemented at The European Organization for Nuclear Research (CERN) to allow the tracking and monitoring of these unusual events. Additionally, the real effect of such an unusual event is presented together with the statistical approach to monitoring and effect evaluation. Considering the collision energy of the beams at 14 TeV, the energy stored in the magnets at 10 GJ (2400 kg of TNT), and the energy carried by the two beams at 724 MJ (173 kg of TNT), prolonged exposure to vibration close to or above the set alarm levels may result in serious safety issues. The presented evaluation of earthquake swarm impact on underground facilities together with the approach for data evaluation can be used for the design of future detectors and accelerators. Additionally, it provides tools for facilities users to present the data in an easy to understand way. This includes the Future Circular Collider, whose purpose is to significantly expand the energy and intensity frontiers of planned particle colliders, with the goal of reaching collision energies of 100 TeV in the quest for novel physics. As a result, even greater standards for beam size and stability will be required.

Dynamic Response Analysis of Mega-Sub Isolated Structures under Multiaxial Earthquakes

“…Considering the actual stress state of the bearing the earthquake occurs, an efficient nonlinear phenomenological model was propos simulate the mechanical behavior of seismic isolation bearings. The design of the structure needs to be considered in many aspects, such as th mulative influence of earthquake swarm (which refers to the occurrence of consec earthquakes in the same area within a short time) [31], which will cause the structu be subjected to earthquake loads several times within a short time, thus increasin earthquake response of the structure. Moreover, because a certain relative displace is generated between the sub-structure and the main structure during the earthquak tion when the actual earthquake exceeds the seismic intensity, the relative displace may exceed the width of the seismic isolation joints and thus lead to the collision bet the sub-structure and the main structure.…”

Seismic Performance Evaluation of a High-Rise Building with Structural Irregularities

“…The elastic-plastic time history analysis was carried out to verify the collapse resistance of the building structure and the damage levels of typical structural members. The collapse resistance was defined by comparing with the limit value of the storey drift (1/120) recommended by the design code, and the damage situation was estimated by the compression or tensile damage factor of the concrete and the degrees of plastic strains of the reinforcing steel bars [22]. In this section, two natural waves and one artificial wave in two directions were selected to carry out the elastic-plastic time history analysis under the rare earthquakes.…”

Advanced Video-Based Processing for Low-Cost Damage Assessment of Buildings under Seismic Loading in Shaking Table Tests

“…In fact, several types of earthquakes may occur depending on the site where the structure is located. In particular, sudden and unexpected high amplitude earthquakes, or so-called high activity earthquake swarm events, can occur, potentially causing damage to civil engineering structures [1].…”