3 seismometers in southern Israel detected Hamas activity just before Oct. 7 attack
Tel Aviv scientists find widely spaced stations picked up heavy vehicle movement in 30 minutes prior to invasion; findings could open way for detection systems to serve security
Sue Surkes is The Times of Israel's environment reporter
Tel Aviv University scientists, who have been working for five years to pinpoint seismic noises created by human activity, have discovered that the unusual flow of heavy vehicles driven by Hamas terrorists toward Gaza’s border with Israel on October 7 last year was picked up by three seismic stations in southern Israel.
In a development that could open new possibilities for using these tools in security and industrial settings, the researchers have retrospectively identified weak but widespread human-induced seismic noise, from 6 a.m. onwards.
At 6:29 a.m., the first of some 3,000 Hamas-led terrorists burst across the border into Israel from Gaza by land, air and sea, killing some 1,200 people and seizing 251 hostages of all ages — mostly civilians — as thousands of rockets rained down on Israeli cities, towns and villages.
Findings of the study, led by Asaf Inbal of the Porter School of the Environment and Earth Sciences and the Sackler Faculty of Exact Sciences, were published in The Seismic Record, a journal of the Seismological Society of America.
The researchers explained that forensic seismology is often used to monitor conventional and nuclear explosions. However, this is the first time in history that weak ground motions resulting from preparations for a terrorist attack have been identified by analyzing the characteristics of seismic noise induced by vehicular traffic.
They believe the discovery demonstrates the potential usage of seismic-based sensing technology to provide early warnings of terrorist activity. However, they emphasize that the identification of these movements in Gaza was conducted retrospectively, months after the attack.
Inbal said, “The Israeli Geological Survey operates a nationwide network of dozens of highly sensitive seismometers that continuously monitor ground motions. This network is primarily designed to detect and locate earthquakes and provide warnings of strong ground shaking caused by large-magnitude seismic events.”
“However, three stations in the network—located in Amazia, Ketziot, and Yatir, between 30 and 50 kilometers (18.5 to 31 miles) from Gaza, recorded unusual seismic noise levels early in the morning of October 7th, 2023. This noise can be attributed with confidence to the vehicular activity in Gaza as Hamas terrorists gathered for the attack. The time frame was between 6 a.m. and 6.30 a.m., before the rocket fire began. The likelihood that the recorded signals originated from Gaza is over 99.9 percent.”
The team analyzed three years of data from the same three seismic stations and found no other instance of seismic noise at all three stations simultaneously or continuing for more than 10 minutes.
The stations are widely spaced. Some 80 kilometers (50 miles) separate Ketziot and Amazia, for example, and on previous Saturdays, there was no correlation between the data recorded at them.
Inbal said, “On the morning of the attack, when local activity near the stations was minimal [the morning of the Jewish festival of Simhat Torah], we found unique widespread seismic amplitudes, which monotonically increased as the time approached for the attack. No known natural or human source on the Israeli side could have generated seismic signals with a distribution and intensity similar to those attributed to Hamas movements.
“Although the outdoor music festival near Re’im [where more than 360 revelers were gunned down] generated some seismic noise, our analysis shows that this noise does not match the strength or location of the noise sources recorded by the Israeli seismic network on October 7.”
The seismic noise intensified as the attack approached. Occasionally, it featured short bursts that allowed the scientists to pinpoint their source and track their progress as the vehicles advanced southward and northward within Gaza, from Rafah in the south to the Erez crossing in the north, during the 30 minutes leading up to the attack.
Inbal continued, “We have good resolution along Salah al-Din Road, a major thoroughfare crossing Gaza from Rafah in the south to Beit Lahiya in the north. We can confirm with high certainty that their forces moved along this route at speeds of 25 to 50 kilometers per hour [15 to 30 miles per hour]. Observations from stations dozens of kilometers from Gaza’s border indicate convoys of heavy vehicles such as bulldozers and trucks carrying operatives.”
“Three minutes before the attack began, we detected noise sources reaching the northern end of Gaza near Beit Lahiya and the southern end near Khan Younis. At the same time, we continued receiving signals from central Gaza, near Nuseirat.
“We know the assault began almost simultaneously along the entire border, so these seismic observations provide further evidence of the extensive deployment of Hamas forces, likely enabling the simultaneous breach of the ground barrier.”
