Wed, 22 Nov 2017 16:19:54 +1300
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How far was my earthquake?


This is an earthquake recorded at 20150221111409NZDT in Kapiti, New Zealand. geonet.org.nz knows it as 2015p137639.

The left sound channel shows horizontal acceleration. The right: vertical. The video shows the vertical and horizontal axes correctly.

At around 2 seconds you'll see, hear, and perhaps feel, a peak in vertical, higher frequency movement. This is the primary or P wave.

After around 4 more seconds the secondary or S wave arrives. This has lower frequencies and has more horizontal component.

The time between the P and S waves is proportional to the distance from the earthquake.

This earthquake was at a distance of about 32km. Divided by 4 seconds this gives a rough factor of 8km per second of difference between P and S wave arrival times.

Here's Wikipedia on seismic waves.

P wave

P wave

S wave

S wave

New Zealand earthquake news propagates well on Twitter at #eqnz. Follow zl2tod.


Mag 5.4, 213km distant, 13km deep

Mag 6.6, 1153km distant, 225km deep

Mag 4.4, 316km distant, 225km deep

Mag 3.8, 50km distant, 39km deep

Mag 4.8, 18km distant, 54km deep

Mag 4.9, 233km distant, 29km deep

Mag 3.7, 41km distant, 39km deep

Mag 4.6, 76km distant, 77km deep

Mag 5.1, 193km distant, 16km deep

Mag 5.1, 113km distant, 11km deep

Mag 5.3, 140km distant, 13km deep

Mag 5.5, 90km distant, 15km deep

Mag 7.9, 4480km distant, 100km deep

Mag 4.7, 128km distant, 15km deep

Mag 5.5, 116km distant, 12km deep

Mag 4.5, 41km distant, 27km deep

Mag 7.8, 263km distant, 15km deep

Mag 3.9, 38km distant, 42km deep

Mag 5.0, 199km distant, 14km deep

Mag 4.4, 44km distant, 37km deep

Mag 4.2, 71km distant, 73km deep

Mag 3.4, 47km distant, 24km deep

Mag 5.1, 104km distant, 80km deep

Mag 4.0, 49km distant, 32km deep

Mag 7.1, 581km distant, 22km deep

Mag 7.1, 581km distant, 22km deep

Mag 4.3, 63km distant, 45km deep

Mag 5.2, 31km distant, 27km deep

Mag 4.7, 31km distant, 28km deep

Mag 5.2, 296km distant, 88km deep

Mag 4.6, 418km distant, 103km deep

Mag 5.2, 37km distant, 24km deep

Mag 5.2, 37km distant, 24km deep

Mag 3.4, 27km distant, 5km deep

Mag 5, 227km distant, 28km deep

Mag 4.6, 95km distant, 11km deep

Mag 4.6, 85km distant, 18km deep

Mag 5, 132km distant, 8km deep

Mag 5.7, 345km distant, 15km deep

Mag 3.8, 35km distant, 5km deep

Mag 5.7, 212km distant, 48km deep

Mag 6.6, 1212km distant, 366km deep

Mag 4.6, 336km distant, 142km deep

Mag 5.1, 122.5km distant, 25km deep

Mag 5.1, 135.4km distant, 110km deep

Mag 4.7, 82.3km distant, 22km deep

Mag 5.4, 180km distant, 39km deep

Mag 5.8, 114km distant, 24km deep

Mag 5.1, 299km distant, 167km deep

Mag 5.8, 1245km distant, 149km deep

Mag 4.1, 62.4km distant, 31km deep

Mag 4.3, 41.5km distant, 5km deep

Mag 4.1, 121km distant, 54km deep

Mag 4.2, 103km distant, 84km deep

Mag 8.5, 8420km distant, 590km deep

Mag 3.6, 17.5km distant, 26km deep

Mag 4.6, 121km distant, 16km deep

Mag 4.1, 120km distant, 47km deep

Mag 5.8, 651km distant, 4km deep

Mag 4.2, 355km distant, 166km deep

Mag 6.2, 214km distant, 52km deep

and again, faster, with foreshock

Mag 5.1, 111km distant, 24km deep

Mag 3.5, 44km distant, 52km deep

Mag 3.8, 73km distant, 35km deep

Mag 3.6, 102km distant, 126km deep

Mag 3.6, 97km distant, 46km deep

Mag 4.3, 16km deep, 67km distant


Deep and distant

How far was my earthquake?