According to Wikipedia, an earthquake swarm is "a
sequence of seismic events occurring in a local area within a relatively short period."
Since I originally built the SeismoSight engine for my own personal use and didn't really care about strict
scientific definitions, my swarm classification and criteria turned out pretty weird.
First of all swarm's id: [type][date].[index]
Types:
- S - Swarm When at least 24 earthquakes of any magnitude are registered within any 15 km
radius circle in a
rolling 24-hour window, this type of swarm is triggered. The swarm is considered closed when the number of
quakes in the same 24-hour rolling window drops to 2 or fewer.
This one was the first type I created, and it was originally aimed at detecting lava-related swarms. In
reality, it also catches aftershock sequences and industrial quakes really well.
- PS - Powerful Swarm When at least 5 earthquakes of M5.0 or higher are registered within any
100 km radius
circle in a rolling 24-hour window, this type of swarm is triggered. The swarm is considered closed when the
number of quakes in the same 24-hour rolling window drops to one or fewer. This type was originally designed
to catch potential foreshocks of strong earthquakes.
- VS - Volcanic Swarm Same as the first type (S), but the center of the circle must also have
a volcano
within 5 km or less. This variant was supposed to detect eruption-related swarms.
- SVS - Super-Volcanic Swarm Same as type S, but it also requires at least one quake inside a
supervolcano area. I created this one specifically to monitor activity in big supervolcano calderas.
- SVPS - Super-Volcanic Powerful Swarm Same as type PS, except it also needs at least one earthquake
inside a supervolcano area. Interestingly, I haven't seen this type trigger even once since 2000.
Date: YYYYMMDD of the first earthquake that started the swarm.
Index: serial number of this swarm type within the day (starts from 1).
Examples:
S20260402.3 - Regular swarm. First quake hit on April 2, 2026 (UTC). This was the third swarm of type S that began on the same day.
SVS20240101.1 - Supervolcanic swarm. The first earthquake occurred on January 1, 2024 (UTC). It was the first swarm of this type on that day.
