SE Turkey earthquakes 6th Feb 2023

Low frequency (0.1-6 Hz) response of the vertical detector of the Mole Valley RaspberryShake seismometer for the morning of 6th February 2023. The two big earthquakes are clearly visible, lasting at least 20-30 minutes. There is an additional M6.0 aftershock just about visible at about 12:10. Only aftershocks larger than about M5.7 can be detected at this distance (~3,300km).

SE Turkey M7.8 & M6.3 01:17 6th Feb 2023

The first, huge (Magnitude 7.8), earthquake to hit the SE Turkey area arrived at the Mole Valley just before 01:24 on the morning of the 6th Feb 2023, followed by a M6.3 aftershock just after 01:34. The combined effects lasted at least half an hour here.

SE Turkey M7.5 10:24 6th Feb 2023

The second major quake to hit the area on the morning of the 6th. It lasted at least 20 minutes. The low-frequency waves that start about half-way through are probably surface waves (Love and/or Rayleigh) and were likely the most damaging.

Wem, Shropshire M3.8 30 May 2022

1-10Hz bandpass-filtered traces from the vertical (EHZ) and two horizontal (N-S: EHN & E-W: EHE) detectors of a significant earthquake in the Midlands, 230km away and 8km deep. On both the P and later S-waves, the quake actually starts about 3 seconds before things really get going: presumably associated with the way the fault moved.

Norwegian Sea M5.2 21 March 2022

The vertical geophone response to a M5.2 earthquake offshore Norway: the image shows the unfiltered trace at the top, the Spectrogram of this trace, a bandpass filtered trace between 2 and 8 Hz and a trace (all in blue) of the 0.2-2.0 Hz frequencies. The P and S-wave arrivals are clearly seen on the 2-8 Hz trace and the Spectrogram but the largest displacements follow on after the S-waves and are very low frequency: they are likely the response to Love and Rayleigh surface waves. The whole event lasted 7-8 minutes in the Mole Valley.

Offshore Fukushima, Japan M7.3 16 March 2022

A big (Magnitude 7.3), deep (63km) earthquake from the subducting plate offshore Fukushima, 9,446km away from the Mole Valley. The tiny event two minutes before, at 14:47, is another quake from the same area but of only Magnitude 6.0 (!).

Walsall, West Midlands M2.8 21st Feb 2022

Clear P- and S-wave arrivals from a 7km deep earthquake, only 176km away from the Mole Valley

Fiji M6.8 16th February 2022

A big (Magnitude 6.8) and particularly deep earthquake (535km) from 16,948km away south of the Fiji Islands - or ~153˚ around the earth. The first arrivals have been refracted through the liquid core (PKP waves). The second phase of arrivals, just over 2 mins later, are probably waves following a similar path after having been reflected at the earth's surface above the epicentre. These are termed pPKP waves.

Reading M1.8 27th December 2021

This is the closest earthquake to the Mole Valley since we started monitoring: 42km away (and 5km deep). It took only 8 seconds for the P-waves to reach us, with the S-waves following 5 seconds later. The whole event lasted no more than 20 seconds. The 3 traces (vertical, N-S & E-W) are only filtered to remove energy below 1Hz.

Acapulco M7.0 8th Sep 2021

This is the big earthquake from ~10km depth below Acapulco on the West Coast of Mexico: 9,167 km away from the Mole Valley ! It hit at 20:47 on the 7th, local time in Mexico. Only P-waves, of course.

Alaska M7.0 14th Aug 2021

This magnitude 7.0 quake occurred in Alaska, nearly 8,000 km away, about half an hour before the big one in Haiti and produced much the same response in the Mole Valley. The quake goes on for nearly four minutes and, as with the Haiti quake, there is no sign of S-Waves, only the main P-wave signal.

Haiti M7.2 14th Aug 2021

This is the big, destructive earthquake in Haiti, as seen from the Mole Valley nearly 11 minutes later - some 7,250km away. The quake is from about 10km depth and there is no sign of any S-waves, which should have arrived about eight and a half minutes after the main P-wave. Of the many aftershocks, only the largest (M5.8) is visible from the Mole Valley - and that only just above the background noise.

Dieppe M3.3: Jun 28th 2021 14:29 UTC

A magnitude 3.3 quake from just offshore France about half way between Dieppe and Le Havre - a mere 169km from the Mole Valley and from a depth of about 5km. The P and S-wave arrivals are clearly seen.

off E Coast North Island, New Zealand M7.3 4th March 2021

M7.3 quake from 16km depth 18,474km away from the Mole Valley (or 166˚ round the world): far enough for first arrivals (c. 13:48, ~20 mins after the quake) to have travelled right through the core of the earth: both liquid & solid (so-called PKIKP-waves). Another phase of arrivals at c. 13:49 was refracted around the solid inner core within the liquid outer core (PKP-waves). The pulse of energy arriving at c. 13:53 is likely a reflected P-wave that travelled half the distance in the mantle, bounced off the ground surface and repeated the process (a PP-wave). There are even further arrivals after this up to at least 15 mins later. At the top is an unfiltered vertical trace. You can see that in spite of travelling from the other side of the earth, the amplitudes still exceed those of noise from local traffic. The lower trace is band-filtered to 1-3Hz while the spectrogram shows the energy within all the frequencies up to 5Hz.

Fukushima M7.1: Feb 13th 2021 14:08 UTC

A big quake from 60km depth. No sign of an S-wave but a big P-wave response that went on for at least 2 or 3 minutes. Bandpass filtered between 1 and 5 Hz.

Petrinja M6.4: Dec 29th 2020 11:20 UTC

A big quake from 1,389km away and 10km depth that took about three minutes to reach us and lasted at least six minutes (in the Mole Valley, at least). It was accompanied by many, many aftershocks and at least a couple of significant pre-shocks. Of these, only 4 quakes above M4.5 have been observable on our seismometer. The recording is bandpass filtered between 1 and 8 Hz.

Steinibach M4.3: Oct 25th 2020 19:35 UTC

Bandpass filtered (1-10 Hz) vertical (Z) and horizontal traces (N-S & E-W).

Lincoln M2.5: Oct 21st 2020 02:49 UTC (depth 230 km !)

Bandpass filtered (3-8 Hz) vertical (Z) and horizontal traces (N-S & E-W).

Southern North Sea M2.6: Oct 5th 2020 03:26 UTC

Bandpass filtered vertical (Z) and horizontal traces (E-W & N-S). First arrivals of P-waves and S-waves are marked.

Pyrenees near Pamplona, Spain M4.3.: Oct 1st 2020 00:21 UTC

Bandpass filtered vertical (Z) and horizontal traces (E-W & N-S). First arrivals of P-waves and S-waves marked.

Jersey M2.8: Sep 16th 2020 02:39 UTC

Bandpass filtered vertical (Z) and horizontal traces (E-W & N-S).

Leighton Buzzard M3.5: Sep 8th 2020 09:45 BST (= 08:45 UTC)

The first of the Leighton Buzzard earthquakes was quite large and stood out from the background noise on the day's seismogram.

Leighton Buzzard M3.5: Sep 8th 2020 08:45 UTC

Raw vertical trace (blue background) and bandpass filtered vertical (Z) and horizontal traces (E-W & N-S). See "Introduction to MVGS Earthquake Monitoring" in "Earthquakes and Seismograms" for interpretation.

Leighton Buzzard M2.1: Sep 13th 2020 23:21 UTC

Bandpass filtered vertical (Z - blue background) and horizontal (E-W and N-S) traces.

Leighton Buzzard M3.0: Sep 22nd 2020 08:32 UTC

Raw vertical trace (blue background) and bandpass filtered vertical (Z) and horizontal traces (E-W & N-S).

Leighton Buzzard M2.1: Sep 22nd 2020 12:39 UTC

Bandpass filtered vertical (Z) and horizontal traces (E-W & N-S).

Comparison of vertical (Z) responses for first four Leighton Buzzard earthquakes

Traces are all plotted at the same scale, clearly showing the differences in magnitude between the four quakes: Top: M3.5 2nd: M2.1 3rd: M3.0 Bottom: M2.1