Magnitude 4.0 earthquake strikes off Silivri coast, felt across Istanbul

A 4.0 earthquake struck off the coast of Silivri in the Marmara Sea on Wednesday, according to Kandilli Observatory. The tremor occurred at 12:13 p.m. local time at a depth of 6.99 kilometers (4.34 miles).

Türkiye’s Disaster and Emergency Management Authority (AFAD), which also monitors seismic activity in the region, reported the magnitude as 3.9.

The tremor was felt across much of Istanbul, causing brief concern among residents. There have been no immediate reports of damage or injuries. Authorities continue to monitor the situation.

A CNN Turk reporter shared real-time updates on the earthquake:

There are reports from people who felt the tremor, particularly in the Silivri and Buyukcekmece areas.

While we are currently in Caglayan and did not feel it here, it’s reported that the earthquake was felt in districts closer to Silivri, especially in Catalca.

Coastal areas seem to have experienced the tremor as well.

Second earthquake with 6.2 magnitude hits Istanbul on April 23

After the first earthquake, a stronger earthquake struck Istanbul on Wednesday at around 12:50 p.m. local time.

AFAD announced that a 6.2 magnitude earthquake had struck off the coast of Silivri, Istanbul, at 12:49 p.m.

According to the information contained in the report, the epicenter is located in the Marmara Sea, Silivri district of Istanbul, where a 6.2 magnitude tremor was recorded.

It was determined that the earthquake, which was felt in the surrounding provinces as well as Istanbul, occurred at a depth of 6.92 kilometers.

Just moments after the 6.2 quake, a third tremor followed. At 12:51:20 p.m. local time, a 4.4 magnitude earthquake struck the Marmara Sea, approximately 14.74 kilometers off the coast of Buyukcekmece, Istanbul.

The tremor occurred at a depth of 7 kilometers and further intensified the alarm in the region.

Timeline after initial 4.0 earthquake in Istanbul on April 23:

Seismologists confirmed that the April 23 event was part of a rapid seismic sequence affecting the Marmara region.

The initial tremor was followed by several aftershocks in quick succession, all recorded within a single hour.

• 12:19 p.m. – 3.9 magnitude foreshock
• 12:49 p.m. – 6.2 magnitude mainshock
• 12:51 p.m. – 5.9 and 4.4 magnitude tremors
• 1:01 p.m. – 4.8 magnitude
• 1:02 p.m. – 4.5 and 4.9 magnitudes
• 1:07 p.m. – 3.4 magnitude aftershock

The clustering of these tremors raised alarm across Istanbul, particularly in districts near the fault line.

Areas most at risk in Istanbul during a strong earthquake

There are districts in Istanbul that are vulnerable in terms of geological structure and urban development.

• Zeytinburnu
• Fatih (Historical Peninsula)
• Bakirkoy
• Avcilar (especially coastal areas and near Kucukcekmece Lake)
• Kucukcekmece (Menekse, Kanarya, Cumhuriyet neighborhoods)
• Beylikduzu (Gurpinar: Pekmez and Pinarkent neighborhoods)
• Buyukcekmece (Devebagirtan region)
• Kumburgaz and Silivri

These zones are marked by loose soil, landslide-prone terrain, and dense construction near the Marmara fault line.

Safer zones in Istanbul in terms of ground stability include:

• Kadikoy
• Camlica
• Aydos
• Upper parts of Kartal and Maltepe

The 6.2 magnitude earthquake off Silivri has prompted immediate government response and technical evaluations across transport, infrastructure, and housing. Metro operations remain stable, and aftershocks are being tracked closely by seismic experts.

Time	Latitude	Longitude	Depth (km)	Magnitude	Location
16:53:10	40.8452	28.3920	25.7	1.8	Marmara Sea
16:45:39	40.8265	28.4422	20.4	2.8	Marmara Sea
16:32:08	40.8463	28.3663	21.8	2.2	Marmara Sea
16:29:12	40.8417	28.3630	22.4	3.2	Marmara Sea
16:25:17	40.7848	28.2417	5.0	3.0	Silivri – Istanbul
16:09:49	40.8610	28.2738	22.4	2.7	Silivri – Istanbul
16:08:38	40.8395	28.4312	22.9	2.4	Marmara Sea
16:07:29	40.8440	28.4035	21.2	3.1	Marmara Sea
16:03:55	40.8620	28.4083	20.5	2.2	Marmara Sea
16:02:24	40.8497	28.3958	20.0	2.2	Marmara Sea
15:57:41	40.8417	28.3782	20.5	2.4	Marmara Sea
15:54:12	40.8473	28.3992	20.0	2.0	Marmara Sea
15:52:24	40.8417	28.3807	21.5	2.7	Marmara Sea
15:50:50	40.8327	28.4317	24.5	1.9	Marmara Sea
15:47:41	40.8442	28.4082	20.0	2.3	Marmara Sea
15:44:36	40.8418	28.4093	20.0	2.0	Marmara Sea
15:44:13	40.8357	28.4362	21.5	2.2	Marmara Sea
15:36:47	40.8365	28.4308	24.0	1.6	Marmara Sea
15:32:45	40.8452	28.4000	21.5	2.2	Marmara Sea
15:27:57	40.8423	28.3983	21.3	2.5	Marmara Sea
15:19:06	40.8427	28.3962	20.7	1.9	Marmara Sea
15:11:25	40.8437	28.4002	21.2	2.3	Marmara Sea
15:01:42	40.8433	28.3938	21.6	2.4	Marmara Sea
14:59:20	40.8417	28.3990	21.1	2.0	Marmara Sea
14:56:35	40.8452	28.3995	22.1	2.5	Marmara Sea
14:45:27	40.8440	28.3977	21.8	2.4	Marmara Sea
14:40:01	40.8427	28.3975	22.0	2.3	Marmara Sea
14:23:37	40.8438	28.3982	21.5	2.1	Marmara Sea
14:16:21	40.8442	28.3957	21.3	2.6	Marmara Sea
13:43:50	40.8478	28.3972	22.0	2.4	Marmara Sea
13:41:27	40.8492	28.3957	20.5	2.1	Marmara Sea
13:39:34	40.8437	28.4012	20.7	2.7	Marmara Sea
13:36:21	40.8435	28.3980	22.2	2.1	Marmara Sea
13:32:04	40.8473	28.3980	22.0	2.4	Marmara Sea
13:23:00	40.8430	28.4008	20.9	2.3	Marmara Sea
13:20:39	40.8438	28.4003	22.3	2.1	Marmara Sea
13:12:12	40.8432	28.3993	20.5	2.2	Marmara Sea
13:09:30	40.8442	28.3988	21.0	2.0	Marmara Sea
13:06:36	40.8427	28.4007	20.7	2.3	Marmara Sea
12:50:25	40.8440	28.3975	21.3	2.4	Marmara Sea
12:40:08	40.8420	28.4015	20.8	2.2	Marmara Sea
12:30:22	40.8448	28.3982	21.0	2.5	Marmara Sea
12:13:00	40.8433	28.3998	22.0	2.4	Marmara Sea