At first, the Gaza tunnels had several fundamental features with other excavation sites in Israel and around the globe, like concealment systems, mines, and burial chambers.
The savage October 7 assault and massacre in Israel demonstrated how, in the decades since it first dug into and concealed itself in the Gaza Strip, Hamas has greatly increased and enhanced its tactical and strategic terror capabilities.

This alarming growth is mostly the result of the famed Hamas tunnels. Prof. Joel Roskin is a geomorphologist and geologist who teaches geography and environment at Bar-Ilan University. He has studied the evolution of the Gaza tunnels over time, analyzed the conditions that led to their formation and growth, and identified the geological and security factors that facilitated their rapid development.

Based on his research, “Underground Warfare in the Gaza Strip and the Military Complexity of Combating It,” Roskin wrote a book chapter three years ago. The scholarly journal Studies in Conflict and Terrorism is currently nearing acceptance of a relevant paper bearing the same name and covering the same ground.

The paper discusses the field data and geopolitical conditions that actually created the fertile environment for the building of the tunnels, drawing on his expertise as head of the terrain research department in the Southern Command in the 2000s and information released by the media.

Extensive documentation of tunnelling activities dates back over 4,000 years — Assyrian sculptures depict engineering teams under Sargon of Akkad’s rule (which lasted from 2,334 to 2,279 BCE) breaking down adversary city walls. In 2002, as American forces pursued Osama bin Laden and attacked Al Qaeda sites, they found a vast network of tunnels linking Afghanistan’s natural Tora Bora cave formations.

At first, the Gaza tunnels had several fundamental features with other excavation sites in Israel and around the globe, like concealment systems, mines, and burial chambers. He clarified, “But each tunnel system is unique and different in relation to the geological, geographic, and geopolitical conditions in place.”

“What is interesting about Hamas is that the rate of growth of the tunnels, not only in size but also in purpose, complemented the development of the organization’s operational concept,” Roskin stated. “It began with the smuggling of goods, progressed to the smuggling of weapons, and later evolved into attack tunnels.”

“The organization’s perspective at this point was tactical. Afterwards, they turned the subterranean into attack and concealment tunnels and enabled kidnappings similar to the 2006 abduction of Private Gilad Shalit,” he claimed.

“The strategic assault tunnels that were discovered during Operation Protective Edge nine years ago represented the next stage. These additional tunnels matched Hamas’s increasing operational thirst as their leaders saw that their operations were consistently successful and that the Israel Defence Forces were only able to provide a token reaction.

Originally utilized as smuggling tunnels
THE FLEDGLING phase started in 1982 as a result of Egypt’s insistence that the border split the town of Rafah between Gaza and Egypt and the peace agreements with Egypt. The purpose of the tunnels created by the locals was to bring back together families that had been divided between the two halves of Rafah and to smuggle commodities.

The tunnels were mostly dug by local miners with well-digging experience, not by terrorists at the time. Smuggling tunnels for weapons and supplies between Rafah, Gaza, and Egypt started to increase in 1994. Rafah became part of the Palestinian Authority’s jurisdiction after the Oslo Peace Accords.

The Israeli Defence Forces’ (IDF) unrealized invasion plans for the Gaza Strip as part of Operation Defensive Shield led to an increase in the use of the underground in 2000, following the second Intifada (Palestinian uprising). Tunnel mining in Rafah and illicit arms smuggling both increased during this time.

Subsequently, the knowledge that Israel was unable to respond effectively spread across Gaza, and Hamas and other parties intensified and expanded their subterranean activities, including detonations beneath IDF positions via attack tunnels. The inaccurate Israeli assessment of an impending peaceful future for the people of Gaza led to a significant decrease in funding for the IDF’s response to the tunnel challenge after Israel withdrew its military and civilian forces from the Gaza Strip entirely unilaterally in 2005, with the goal of enabling Gazans to independently forge a new future, according to Roskin.

However, the smuggling tunnels between Egypt and Gaza increased to hundreds in number, as well as in size, length, and quality. They also had a greater spatial distribution and entry and exit shafts that were clearly marked out in sheds, through which both legal and illicit goods were freely transported.

The profitable venture and Gaza’s armament against Israel continued unchecked by the Egyptians. Rather than using only wood planks as in the past, Israel contributed concrete for use in the building of the tunnel walls. As a result, Hamas and the Palestinians in Gaza armed themselves, started producing weapons on their own using supplies that were smuggled in, and began digging offensive tunnels that were now aimed toward Israel.

Conquest of the Gaza Strip
Following the successful abduction of Shalit and the violent takeover of the Gaza Strip by Hamas from the Palestinian Authority in 2007, underground warfare in Gaza flourished and evolved into a comprehensive joint guerilla-terror warfare concept, the outcomes of which we are currently witnessing: by 2007, access tunnels had been dug to locations where indirect ballistic rocket and mortar firing positions were located, as well as to locations where smuggled goods, logistic centres, and command and control headquarters were located.

As part of their all-encompassing strategy, Hamas began using the underground in 2009 and created roughly 35 assault tunnels beneath Israel’s 1949 armistice line, some of which pierce hundreds of meters into the Jewish state. These tunnels were now intricate, multi-story subterranean caves and tunnels with chambers, halls, and warehouses instead of just lengthy transportation lines connecting points. The underground “city” had numerous entrance holes, most of which were in residential buildings and were inclined, vertical, or horizontal. A “tunnel culture” emerged in Gaza, involving educational visits by kindergarten through high school students, wedding portraits, and tours of the subterranean tunnel network.

It is reasonable to presume that beneath the Gaza Strip is a vast network of multistory tunnels spanning dozens, if not hundreds, of km. Roskin pointed out that 3D mapping and the presentation of imagery require highly secret information, and that effectively mapping the tunnel network from space or the ground is challenging.

Even though Israel built a costly and advanced underground barrier on its side of the 1949 armistice line a few years ago, it was unable to stop Palestinian terrorists from using the tunnels to enter Israel. Thus, on October 7, terrorists from Hamas were able to enter the border zone through underground tunnels without being seen by IDF surveillance cameras, thanks to a barrier intended to keep them out.

In addition to Israel’s unilateral 2005 pullout from the Gaza Strip and the challenges it had in locating the tunnels necessary for their construction, Roskin highlights the geological characteristics of Gaza that made mining easier. Layers of sand and dust have accumulated over time, hardening and coalescing into sedimentary units of different cohesiveness that range in thickness from one to two meters in the southern Gaza Strip. These layers do not become rock.

These units tend not to collapse, are sufficiently stable, and are quite convenient for manual mining. The depth of the tunnels was typically four to twelve meters until the 2000s. They were unstable above four meters, thus there was typically no need to make the investment to drill down to a depth of more than 12 to 15 meters. This was not based on systematic mapping or measurements of the tunnels by the Israeli army; rather, it was based on general observations and an unintentional outcome of geophysical study in a simulated area.

However, according to ROSKIN, Hamas started to dig larger, longer, and deeper specimens once he continuously learnt and developed. In addition, human adaptation was almost complete, as were the means of support, communication, and electricity.

It’s a challenging place to be at first, both medically and psychologically. In addition to concealing the entrances and exits, Hamas benefits from the tunnels’ urban position because it is close to essential infrastructure like communications, water, and electricity,” the speaker stated. “Even without an electricity network, air ventilation systems into the tunnels are possible with the help of underground generators.”

The geomorphologist explained that there are a number of technological detection techniques, some of which are based on the transmission of a wave that may partially return depending on the qualities of the soil. This helps to explain both the simplicity of mining and the difficulties of detection.

“However, in this instance, the search is essentially fruitless, as a minuscule cross-sectional area of air in relation to the subsurface medium, typically measuring no more than one or two meters in width and height, is sufficient to permit bidirectional movement within the subsurface,” Roskin remarked. Additionally, “one must be in the same place in the ground or on the ground above the tunnel in order to activate detection.”

Finding surface-level indicators of construction, maintenance, and activity—such as earth piles—is an additional method of finding tunnels. He stated, “To do this, you need to fuse intelligence work at high resolution, looking at small changes in the terrain at short time intervals.” This is particularly difficult in an urban setting. These changes may be hidden within buildings in the city, or they may be absorbed by the bustle of daily life.

According to Roskin, the public’s understanding of the Hamas tunnels was, up until recently, quite naive, viewing them as fighters’ passageways and a potentially dangerous infrastructure. However, Hamas has mercilessly combined guerilla warfare, terrorism, and military warfare to build its offensive and defensive structure, which includes an extensive integration of the underground system.

“This all-encompassing guerilla-fare approach combines above-ground combat techniques with tactical, strategic, and logistical tunnels. He said, “These conditions are indeed a challenge for full offensive IDF treatment. The underground is integrated into all aspects of the battle, including gunfire, covertly concentrating forces and probably also for transporting prisoners and hostages and for holding them in secure medical conditions.”