Live Earthquake Helicorder — Soquel, Santa Cruz County, CA

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 in Soquel, Santa Cruz County, California 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' complete hand-built horizontal-pendulum seismograph in the Soquel basement — the wooden frame and boom arm, the cylindrical magnet mass, the moving coil, and the fish-hook pivots. — The original, whole — David Reynolds' hand-built horizontal-pendulum seismograph: the boom arm, the cylindrical magnet mass, the moving coil, and the fish-hook pivots (lower left), just as it stood in the basement recording 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.

A second earthquake on the tape

The Loma Prieta fragment wasn't the only one David kept. A year later, on the night of October 24, 1990, his seismograph caught a magnitude‑5.7 earthquake near Lee Vining — between Mono Lake and the eastern edge of Yosemite, roughly 150 miles away. The USGS called it one of the most widely felt earthquakes ever reported in California, shaking the ground from San Francisco to Reno; the shock loosed rockslides that closed two roads into Yosemite. David marked this tape in the same steady hand as the first — "R=5.7 · Wed 10-24-90 · 11:16 PM · Yosemite / Mono lake" — clocking the arrival to the minute on an instrument he built himself.

David Reynolds' paper seismograph tape recording the magnitude-5.7 Mono Lake earthquake of October 24, 1990 — a quiet blue trace, timing marks, and a heavy off-scale event blot, annotated by hand 'R=5.7 · Wed 10-24-90 · 11:16 PM · Yosemite / Mono lake.' — A second survivor — David's tape recording the M5.7 Mono Lake earthquake of October 24, 1990: the quiet trace, his 11 PM timing mark, and the off-scale event, annotated in his hand.

Two surviving tapes, a year apart, both annotated by hand — the analog ancestors of the live helicorder above and the detected-earthquake catalog below. Same basement, same patch of ground, same idea: keep a record of what the earth is doing.

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)

What the Station Has Caught

A seismic station is only as good as what it records. Across about seven weeks of continuous listening in the summer of 2026, the EQ-1's automated detector flagged 8,616 bursts of ground motion — and 25 of them line up, to the minute, with earthquakes in the official USGS catalog: from local California shocks to a magnitude‑7.5 in Venezuela, more than 6,000 miles away.

Chart of every ground-motion event the Soquel EQ-1 detected from late May to mid-July 2026, with 25 events matched to cataloged USGS earthquakes — red for regional CA/OR/NV quakes, orange diamonds for distant teleseisms. — Every ground-motion event the station detected (faint dots), with the 25 confirmed earthquakes marked — red for regional CA/OR/NV shocks, orange for distant teleseisms. The M5.6 Redwood Valley quake, top, is the strongest the station recorded.

On June 24 alone, the station registered a magnitude‑5.6 quake up in Redwood Valley — then, within hours, the magnitude‑7.5 Venezuela earthquake and a magnitude‑6.9 off the coast of Japan. One homemade-lineage instrument, in one Soquel basement, feeling three corners of the Pacific in a single afternoon.

See the full detected-earthquake catalog →