<p>Interesting question. This time as often reported is referred to as the <em>origin time</em>, and ideally this should really correspond to the start of the rupture (rupturing of the fault, breaking of the materials). See e.g. <a href="https://gfzpublic.gfz-potsdam.de/rest/items/item_4109_1/component/file_4110/content" rel="nofollow noreferrer">this document</a>.</p>
<p>Most networks and earthquake services automatically determine this origin time together with the location of the earthquake simply by fitting the arrival times of the seismic waves recorded at the stations. This means finding the location and origin time of the earthquake <span class="math-container">$(x_0,y_0,z_0,t_0)$</span> that best fits the recorded arrival times. This procedure views the earthquake source as a dimensionless point, and I could imagine that the result might differ slightly from the actual start time of rupture, especially for large ruptures and large earthquakes.</p>
<p>This result might be improved using further techniques such as finite-fault inversion (see e.g. <a href="https://pubs.geoscienceworld.org/ssa/bssa/article/92/4/1192/120765/Source-Description-of-the-1999-Hector-Mine" rel="nofollow noreferrer">this paper</a>), in which one tries to estimate the whole rupturing process on the fault. I won't go into detail but the parameterization usually requires further prior information on the earthquake, such as the orientation and size of the fault, etc.</p>

CC BY-SA 4.0
2024-01-24T21:10:20.183Z
2024-01-24T21:10:20.183Z
GentleMin
<p>For example, Time for the 2023 Turkey–Syria earthquake is 2023-02-06 01:17:35
What time does this exactly represent, the start of earthquake's wave or pick of the wave or something else?</p>

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2023-02-14T03:21:14.937Z
Or likewise, the start of the movement of the fault, the peak of the movement, or the end of the movement (since that's the source of the wave).  Great question I now share
JeopardyTempest
<earthquakes>
Which point of an earthquake wave is considered as the earthquake's time?
user28480
# Which point of an earthquake wave is considered as the earthquake's time?

(Asked by: username_0 on 2023-02-13)

For example, Time for the 2023 Turkey–Syria earthquake is 2023-02-06 01:17:35
What time does this exactly represent, the start of earthquake's wave or pick of the wave or something else?

**Tags:** earthquakes

> **Comments:**
> **username_1**: Or likewise, the start of the movement of the fault, the peak of the movement, or the end of the movement (since that's the source of the wave).  Great question I now share  

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## 1 answers

### Answer by username_2 on 2024-01-24. Score: 2

Interesting question. This time as often reported is referred to as the *origin time*, and ideally this should really correspond to the start of the rupture (rupturing of the fault, breaking of the materials). See e.g. [this document](https://gfzpublic.gfz-potsdam.de/rest/items/item_4109_1/component/file_4110/content).

Most networks and earthquake services automatically determine this origin time together with the location of the earthquake simply by fitting the arrival times of the seismic waves recorded at the stations. This means finding the location and origin time of the earthquake $(x\_0,y\_0,z\_0,t\_0)$ that best fits the recorded arrival times. This procedure views the earthquake source as a dimensionless point, and I could imagine that the result might differ slightly from the actual start time of rupture, especially for large ruptures and large earthquakes.

This result might be improved using further techniques such as finite-fault inversion (see e.g. [this paper](https://pubs.geoscienceworld.org/ssa/bssa/article/92/4/1192/120765/Source-Description-of-the-1999-Hector-Mine)), in which one tries to estimate the whole rupturing process on the fault. I won't go into detail but the parameterization usually requires further prior information on the earthquake, such as the orientation and size of the fault, etc.


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