trigger mechanism and the driving process that govern the evolution of the swarm in space and time. The Hochstaufen earthquake swarm in Bavaria, with 2-km-deep foci, is one of the rare examples where an indisputable relationship between seismic activity and precipitation could be established. Earthquake swarms raise public-safety issues: first because the end of seismic activity cannot be ascertained; secondly because one can never be sure that another earthquake with a magnitude larger than those of previous shocks in the sequence will not occur. (The 2009 L'Aquila earthquake in Italy is emblematic, with an MW 6.3 shock following a swarm activity with magnitudes between 1 and 3.) Even though swarms usually generate moderate shocks, the persistence of felt earthquakes for a long time can be disruptive and cause distress to the population. Examples The following examples were chosen for peculiarities of certain swarms (for instance: large number of events, complex interaction with larger shocks, long period of time, ultra-shallow focal depth), or because of their geographical region, some swarms occurring in otherwise aseismic regions. It is not intended to be a list of all the swarms happening worldwide. Asia India Since 11 November 2018, an earthquake swarm has been observed in the region of Dahanu, Maharashtra, an otherwise aseismic area. Ten to twenty quakes are felt daily, with magnitudes usually smaller than 3.5 (maximum magnitude 4.1 in February 2019). Even with this low-level of magnitude, two shocks proved destructive and even lethal, probably because their foci were very shallow. Bamhori village in Seoni district is also experiencing regular earthquakes since February 2000. Philippines An earthquake swarm occurred from early April 2017 to mid August 2017 in the Philippine province of Batangas. Four shocks in the 5.5–6.3 magnitude range (2017 Batangas earthquakes) caused damage in southern Luzon; they occurred at the beginning of the swarm: Ms5.5 (4 April), Ms5.6 and Ms6.0 (8 April), and Ms6.3 (11 April). The swarm origin of the 3 first major quakes seems established since they had practically the same epicentre; they occurred within the crust (7–28-km depth range). However, the strongest and latest quake does not seem related to the swarm: its epicentre is 50 km away, and its focal depth is moreover very different (177 km, according to Phivolcs, the local seismic monitoring agency, a value which classifies this quake as an "intermediate-depth event"). This example shows how complex can be interaction between a swarm