Seismology & Data

Live ground motion from Bosco's home seismic station in Soquel, California.

Live Helicorder

Live 24-hour helicorder trace from the Soquel seismic station — Each horizontal line is 60 minutes of ground motion — time runs left to right, top to bottom. Darker traces mean stronger motion. A 24-hour rolling window recorded by a home station in Soquel, California, refreshed here automatically every five minutes. **Click the chart to open it full-size and read the timestamps and traces.**

The RockPile keeps an eye on the living earth, not just the fossil one. A seismic station at Bosco’s Soquel home records ground motion around the clock; the live helicorder below refreshes on its own every five minutes.

The Instruments

This station has watched the same patch of ground for two generations. The original seismograph was hand-built by David Reynolds (W6TQP), Bosco's father-in-law — a horizontal-pendulum design with a moving coil swinging in a permanent-magnet field, near-frictionless pivots, and a needle tracing ground motion onto paper tape. It was recording in the basement when the Loma Prieta earthquake struck on October 17, 1989; the shaking knocked the recorder from its shelf and tore the tape mid-trace — a fragment David labeled by hand and kept.

Bosco keeps the watch today from the same Soquel home. His EQ-1 seismograph sits in that same basement, built into the very case David used, and feeds the live helicorder above — it's tuned for distant earthquakes. Alongside it he runs a second, self-contained geophone sensor indoors, in a spare room: where the EQ-1 registers the far events, the geophone tells him whether a quake is close to home. Between them the two instruments cover both ends — the world's big distant shocks and the local ground right under Soquel.

Bosco's EQ-1 horizontal-pendulum seismograph, installed in David Reynolds' original case in the basement — The station today — Bosco's EQ-1 horizontal-pendulum seismograph, in the basement in the same case David built for his, feeding the live helicorder.

David Reynolds' original hand-built seismograph — the coil, magnet, and boom — The original — David Reynolds' hand-built seismograph: the moving coil and magnet that recorded Loma Prieta in 1989.

The 1989 Loma Prieta earthquake on David Reynolds' paper tape, torn when the recorder was knocked off its shelf mid-quake — The record itself — the 1989 Loma Prieta quake on David's paper tape, torn mid-trace when the shaking knocked the recorder from its shelf, labeled in his hand.

Station Specifications

Seismograph	Windows helicorder pipeline — 24-hour rolling PNG
Seismo update	Every 5 minutes (automated upload)
Instruments	EQ-1 seismograph (basement, distant quakes) + self-contained indoor geophone (near-home)
Location	Soquel, California (Santa Cruz County)