This page records incidental seismic observations logged at EPSO.  Overseas, Australian, Local and  Mining related events are logged on separate pages.

Date	Time (UTC)	What	Summary Seismogram	PSN data file
2012-05-08	11:26:40	A small ≈M1.3 event located at around 51km from EPSO.  But this event was also weakly recorded at ARMA and CMSA, from which the ASC computed an approximate epicentre position of -30.92, 149.30, and a depth of 28km.  This is only 12km distant from the best estimated epicentre location* of -30.83, 149.37 for the 1969 M5.0 Coonabarabran Earthquake (*McCue, 2011).  This 1969 event was one of the 12 strongest earthquakes ever recorded in NSW, and did minor damage to Coonabarabran township.	S6000 triaxial	psn
2012-04-11	08:38:32	Gigantic Magnitude 8.6 Earthquake located off the West Coast of Northern Sumatra, Indonesia.  This event's epicentre was along the same fault which caused the devastating Boxing Day Earthquake and tsunami of 26th December 2004, but due to the strike-slip nature of the fault's surface rupture, no large displacement of seawater occurred and the resulting tsunami was small.  At EPSO, located some 7000km distant from the epicentre, the ground moved backward and forward with a peak displacement amplitude of 4.3mm, with a period of around 27 seconds.  This may be compared with the 1.4mm displacement caused by the Tōhoku earthquake of 11th March 2011,  and the 2.4mm displacement caused by the Chile Earthquake of 27th February, 2010.   It's unlikely I'll ever again see such a large ground displacement at EPSO from any event, overseas or otherwise.	VM hor acceln VM hor velocity VM hor acceln (+/- 12h)	psn psn psn
2012-03-23	09:25:14	The biggest Australian earthquake for around a decade.  This Magnitude (Mw 5.4) event occurred nearby the remote settlement of Ernabella, South Australia.  Robert Herrmann’s moment tensor analysis for this event may be found here.  GA's ML estimate was 5.7, whereas my ML (referenced to my Ranger SS-1 Vertical instrument) was 4.6.	VM hor acceln VM hor velocity FBV Z velocity S6000 triaxial SS-1 vertical	psn psn psn psn psn
2012-03-14	19:07:44	A relatively small quake off the Off W Coast of South Island, New Zealand, appears to have generated a conspicuous T-wave, where acoustical water waves have been generated on the sea floor by the earthquake, and propagated until they encountered Australia's continental shelf, where some of the acoustical energy was converted back to seismic waves.  The Great Circle distance from EPSO to this earthquake's epicentre is 2174km.  The distance from EPSO to the edge of the Australian continental shelf (on the direct EPSO-earthquake track) is about 380km.  From this location, a seismic P-wave takes around 54 seconds to travel to EPSO.  By analysing the right-hand seismic traces, the delay between the earthquake's origin time (19:07:44) and shaking commencing at EPSO (19:28:44) resulting from the T-wave arrival, is around 1260 seconds.  Assuming this shaking was due to T-waves traveling via the direct Great Circle track and impacting the Australian continental shelf offshore from Sydney, these waves were propagating in the ocean for 1260-54=1206 seconds and covered 2174-380=1794km.  In this case the derived speed of the T-waves is 1206/926=1.3km/s in the ocean.  But if the T-waves impacted the Australian continental shelf at the closest point to the epicentre (i.e. eastern Tasmania, 1480km distant from the epicentre, and 1280km from EPSO), from this location a seismic P-wave would take around 167 seconds to travel to EPSO.  So via this route, the T-waves would have propagated for 1480km for 1206-167=813 seconds, suggesting a T-wave propagation velocity of 1.8km/s.  Therefore the ocean T-wave propagation speed is in the range 1.3-1.8km/s.  The average of these two limits is around 1.5km/s which is approximately the speed of sound in seawater, and is consistent with the propagation of the T-waves waves via the so called SOFAR channel.  Most of the spectral energy in the T-wave induced shaking observed at EPSO, is contained within the 1.5-2.6Hz spectral band.	S6000 SS-1 vertical	psn psn
2012-01-05	06:00:00	Vertical motions recorded from EPSO's new Inyo Force Balance Vertical (FBV) instrument, during the passage of an intense overhead thunderstorm.  At this time the FBV instrument was not barometrically isolated and therefore susceptible to detecting perturbations in atmospheric pressure, which were considerable during the passage of the storm.  The FFT spectrum of this 40m dataset, shows pressure perturbations peaking in amplitude at around a 60s period.	Inyo FBV	psn
2011-12-04	19:04:42	Small ML=0.3 event at 47km range from EPSO, with striking similarity to an event logged 2011-05-16 10:40:57  The range and general appearance of these two trace codas are extremely similar, and the 3-axis traces for the first 0.2s are practically identical, suggesting the events have a common origin.  Analysis of the initial P-wave arrival by the ASC indicates that the event location was in a general eastwards direction from EPSO, which is in an area of ancient volcanism, quite interesting to drive through.	S6000 triaxial	psn
2011-12-02	01:31:36	Presumed mining blast from around  -32.62, 151.17 (ASC) but with unusually strong low frequency components which registered unusually strongly on Volksmeter long period instrument.  S-6000 ML=2.3, Volksmeter ML=3.5.	S6000 VM hor acceln VM hor velocity	psn psn psn
2011-11-22	18:05:12	Arrival of P-waves from a M6.6 quake in Beni, Bolivia.  This arrival  had an initial strong vertical peak velocity of 7.6μm/s, of frequency around 2.5Hz.  Significant amplitude long period waves (i.e surface waves) didn't follow this arrival, an effect which is caused by the quake's great depth, of  about 533km.	S6000	psn
2011-10-14	11:29:45	Nearby thunderclap recorded on Sprengnether S-6000	S6000	psn
2011-10-11	03:30:00	D4 Bulldozer working a few metres from EPSO's vault.  This induced several northward-falling step functions in VM tilt, and peak ground velocities of around 70-75um/s horizontally and 17um/s vertically.	VM hor acceln S6000	psn psn
2011-10-05	05:00:00	D4 Bulldozer clearing firebreaks 270-440m from EPSO's vault.	S6000	psn
2011-08-10	02:27:48	Possible ML=2.0 Mining Blast, apparently from range=249km, but with unusually low frequency components.	VM hor acceln VM hor velocity L15B triaxial SS-1 vertical	psn psn psn psn
2011-07-29	00:10:00	Our neighbour chopping wood, 220m distant.	SS-1 vertical	psn
2011-07-27	23:55:00	Our Toyota sedan car returning up our driveway.	L15B triaxial SS-1 vertical	psn psn
2011-07-27	22:45:00	Our Toyota sedan car departing down our driveway.	L15B triaxial SS-1 vertical	psn psn
2011-07-18	09:00:00	Relatively weak microseismic noise.  Volksmeter RMS acceleration = ~0.4um/s/s & RMS velocity = ~0.25um/s.  Peak period = 4-7s.  Ranger SS-1 Geophone (vertical) RMS velocity = ~6nm/s.  60m records	VM hor acceln VM hor velocity SS-1 vertical	psn psn psn
2011-06-21	14:49:31	Step function change in EPSO's pier tilt, toward the North.	VM hor acceln	psn
2011-06-21	14:30:05	Step function change in EPSO's pier tilt, toward the South East.	VM hor acceln	psn
2011-06-04	23:00:00	Exceptionally strong microseismic noise.  Volksmeter RMS acceleration = ~1.1um/s/s & RMS velocity = ~1.4um/s.  Peak period = 7.4s.  Ranger SS-1 Geophone (vertical) RMS velocity = ~9nm/s.  60m records.	VM hor acceln VM hor velocity SS-1 vertical	psn psn psn
2011-05-30	12:37:08	Step function change in EPSO's pier tilt, toward the South East, following a period of light rain (13mm total).	VM hor acceln	psn
2011-05-22	16:42:24	Two small teleseismic quakes (from the Philippines) arriving concurrently to give the impression of a nearby regional event.	SS-1 vertical	psn
2011-05-16	10:40:57	ML=0.9  Small event at ~47km range	L15B triaxial SS-1 vertical	psn psn
2011-04-19	06:05:00	Chopping firewood, 35m NE of EPSO, Australia	L15B triaxial SS-1 vertical	psn psn
2011-04-18	19:37:51	Passing kangaroos.  Note the constant pulse repetition frequency.	L15B triaxial SS-1 vertical	psn psn
2011-04-14	08:22:13	Step function on Volksmeter N-S acceleration channel, most likely due to friction from electrostatically charged dust bridging Volksmeter pendulum and capacitor plates.	VM hor acceln	psn
2010-12-30	09:27:04	18m-tall 1-ton tree felled 35m NE of EPSO, Australia.  Caused a step-function on Volksmeter acceleration trace	VM hor acceln L15B triaxial SS-1 vertical	psn psn psn
2010-12-25	14:50:30	Mysterious strong overnight twangs, strongly N-S polarised (geophone rotated 90 degrees, so apparent E-W channel is N-S)	L15B triaxial	psn
2010-12-24	07:36:10	15m-tall tree felled 30m NE of EPSO	L15B triaxial	psn
2010-12-23	17:38:13	Mysterious strong overnight twangs, strongly N-S polarised.	L15B triaxial	psn
2010-11-10	17:24:38	Nearby lightning strike	SS-1 vertical	psn
2010-10-23	16:48:57	Large tree limb falling, about 100m NW of EPSO	L15B triaxial	psn
2010-10-15	22:25:00	Exceptionally strong microseism noise	SS-1 vertical	psn
2010-10-11	23:32:00	Our clothes washing machine commencing 980rpm spin cycle	L15B hor velocity	psn
2010-09-24	16:42:21	Passing kangaroo or wallaby	SS-1 vertical	psn
2010-01-02	00:00:00	Nearby creek (220m distant) in major flood	SS-1 vertical	psn

Sensors used for these measurements include the Volksmeter (VM), Kinemetrics SS-1 Ranger (SS-1), Marks Products L-15B (L15B) and Sprengnether S-6000 (S6000)