BERLIN — Two bomb alerts at the official residence of German President Roman Herzog in Berlin have caused little stir this summer.
After all, the American-made explosives discovered by construction workers had been buried for more than half a century - and bomb experts had already called on the stately castle more than 20 times last year to salvage undetonated ammunition from World War II.
The legacy of the Anglo-American air raids on Berlin in 1945 remains explosive. In a final blow to the Nazi regime, Allied planes dropped around 50,000 tons of bombs on the German capital. Now, as the city experiences a boom in construction, undetonated explosives are turning up almost daily.
Members of the city's war-materiel removal office pore over wartime aerial photographs to determine where undetonated bombs may still be hiding. "You can see if the bomb made a large or small crater," says Peter Jung, Berlin's chief ordnance technician. "If the crater is small, you can assume that the bomb didn't detonate."
Mr. Jung heads the police bomb squad that is called out three to four times a day. Sometimes the objects turn out to be firecrackers or other false alarms. But often the objects are explosives. Last year his nine-member team recovered 75 tons of unexploded ammunition, including 24 bombs weighing more than 100 pounds each.
Jung stresses that the danger to people is minimal, as long as civilians notify the police and do not tamper with the explosives. Ammunition has been found in places as varied as a church belfry and the construction site of the new chancery building.
In 1994, three construction workers were killed in an accident involving an undetonated bomb. In February, five children were injured after playing with a hand grenade found in a courtyard.
Even after 50 years buried underground, bombs can still explode. Jung says that a common World War II Soviet hand grenade has a safety catch only a little thicker then a paper clip. If the wire rusts through, the grenade can explode on its own.
One explosive that continues to pose a threat is a time-activated bomb, which is detonated by a chemical reaction. Although such bombs were designed to explode within 72 hours of impact, some have laid dormant for decades. These bombs, whose trigger mechanisms cannot be removed, must be detonated on the spot by bomb experts.
Half a century after the war's end, time bombs still explode in Oranienburg, a small town a few miles north of Berlin. In the past 25 years, four bombs self-detonated, and more than 40 have been discovered since 1990. Twice last winter, 8,000 inhabitants were evacuated while old American bombs were salvaged. Several schools were closed during the spring while experts searched for more unexploded bombs.
Sitting in his office at the Berlin "detonation grounds," Jung remains cool about his job. "I've always said that if you're afraid, you have to quit," he says, fiddling with a defused hand grenade. "We just have to be cautious."
A large man with a crewcut and dark green jumpsuit, Jung has been with the bomb squad for 10 years. As he walks through his workplace in a wooded area in southwest Berlin, Jung shows off recent discoveries: rusty bombs, artillery shells, rocket-launched grenades, and tank mines, neatly stacked in subterranean bunkers. Twice a year his team detonates the explosives on a nearby field.
Jung says his bomb squad will be busy for at least 20 more years, though the exact number of undiscovered explosives is difficult to estimate.
His work has become an unspectacular occurrence in the city. The last time his men rushed to the president's residence, the unperturbed Mr. Herzog headed to a popular shopping street to eat ice cream with his wife while he waited for an allclear.