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ichigan Shake

The surface of Earth shakes all the time. Sometimes in response to natural events, close or far away, and all of the time from human activity. This shaking can be violent and damaging, such as from large earthquakes, volcanic eruptions or nuclear explosions; other times the shaking is much less, such as landfall of big storms or mining explosions. The many sources of Earth shaking produce characteristic patterns of vibrations that a seismometer records. Earthquakes, explosions, storms, building collapse, traffic all create different patterns. Michigan has few natural shaking sources, but ample human activity.

The Michigan Shake project tracks local shaking from audience response to game moments in the largest college football stadium in the nation: the Michigan Stadium. This locally sourced seismic signal is irregular and protracted, with ups and downs, unlike sudden energy releases from an explosion, or more steady city noise.

The audience energy is small compared to natural earthquakes, perhaps less than Magnitude 1 on the seismic magnitude scale, but more than enough to shake the stadium and its occupants. Specific game events, like touchdowns (TDquakes) and band play, are easily recognizable, while shaking from the visiting team's TDs is much less impressive.

Because the seismometer is not calibrated for its specific location (surprisingly, test explosions in the stadium were not approved by facilities staff), we use the Michigan Magnitude (Mum), which is the 10log value of maximum shaking (maximum count); see explanation below. Whether Mum will become a global standard depends on the team's season.

UMstadium

A portable Raspberry Shake seismometer (R208E) is located in a top secret location inside the University of Michigan Stadium, at the corner of S Main and W Stadium in Ann Arbor, MI (map).

A reference Raspberry Shake unit (R2FF2) is located in a residential area, about 6km to the NW.

The official USGS seismic station in the area is US.AAM, about 8.5km to the NE.

Managed by Ben van der Pluijm, Professor of Geology, University of Michigan-Ann Arbor, USA. Comments welcome.
Email: vdpluijm@umich.edu Twitter: @vdpluijm


Noisy location. Gates open for public at ~5:30p (21:30UTC) for first public team practice.

M7.8 earthquake, nearly 12,000km (7,500mi) away (after some noise filtering).
Fiji; 2018-09-06 15:49:14 UTC, >600 km depth

M7.5 earthquake, 14,800km away.
Sulawesi, Indonesia; 2018-09-28 10:02:43 UTC, <10km depth

9/8/18, Western Michigan v Michigan 3-49 (TD=touchdown)

TD 2; Mum=3.2

TD 3: Mum=3.1

TD 5: Mum=3.0

TD 6: Mum=2.8

When band engages (and synchronizes) audience: Mum=3.3

Preliminary observations: Slighly decreasing MichiganMagnitude (Mum) as TDs accumulate in a one-sided game, while the band keeps audience lively.

9/15/18, SMU v Michigan 20-45

The team enters, the crowd responds. Mum=3.2

Michigan's first TD. Mum=3.1

SMU counters; audience unimpressed. Mum=2.8

Michigan has taken control. Hicks pass intercepted, Metellus return for 73 yds TD. Mum=3.1

9/22/2018, Nebraska v Michigan 10-56

Surprisingly quick Michigan TD against stronger? opponent. Happy crowd: the biggest audience response this season so far. Mum=3.4

Second Michigan TD, soon after first. Mum=3.2

Third TD. Michigan clearly in control, and decreasing audience response. Mum=3.1

More points on the board. TDs getting easy. Snack time. Mum=3.0

Once more, to warm up the crowd with TD and band. Mum=3.1

On-site spotter: Sahil Tolia

10/13/2018 Wisconsin v Michigan 13-38

K. Higdon rushing TD Mum=3.3

J. Metellus interception Mum=3.3

Singalong to "Mr. Brightside" Mum=3.6

L. Hill interception return for TD Mum=3.4

The rowdiest game so far (many swings over 2000).
On-site spotter: Sahil Tolia

 

Real-time Shaking of Michigan Stadium seismometer

Click on colored triangles to see seismometer readings from growing RaspberryShake network around the region and world.

Station R208E

Live Web: https://raspberryshake.net/stationview/#?net=AM&sta=R208E

Recent Helicorder Displays: http://35.0.115.239/heli/

Magnitude

Ml = log (A/T) (+ F(h,Δ) + C)

Ml = local wave magnitude, with A is amplitude of signal (green), T (or λ) is dominant wavelength (red); typically using signal of first 5 seconds. F is a correction due to earthquake depth, (h) is distance from station (Δ in degrees), C is regional scale factor; here, F and C are zero.


Mum = Michigan Magnitude

Mum = log(count); count is event peak amplitude; wavelength is same for each event, so unused here.


Md = 1.86 x log (t) - 0.85

Md is duration magnitude, with t duration of shaking. (approx: Ml = 0.94 x Md - 0.16)

Reference Stations

AM.R2FF2 (Ann Arbor residential home):
https://raspberryshake.net/stationview/#?net=AM&sta=R2FF2

US.AAM (Ann Arbor station):
https://www.iris.edu/app/station_monitor/#Today/US-AAM/webicorder/
https://earthquake.usgs.gov/static/earthquake-network-operations/Seismic_Data/telemetry_data/AAM.png

Earthquake Event Pages

USGS: Latest Significant Earthquakes

IRIS: http://ds.iris.edu/wilber3/find_event

GFZ: https://geofon.gfz-potsdam.de/eqinfo/seismon/globmon.php

EMSC-CSEM: https://www.emsc-csem.org/Earthquake/significant_earthquakes.php


20-oct-18 15:27