People wearing masks of skulls protest against violence in the country, in Mexico City on November 27, 2011. More than 40.000 people have been killed in rising drug-related violence in Mexico since December 2006, when President Felipe Calderon deployed soldiers and federal police to take on organized crime. AFP PHOTO/Alfredo Estrella (Photo credit should read ALFREDO ESTRELLA/AFP/Getty Images)

MEXICO CITY -- Mexico has been profoundly shaken by atrocities and high-level corruption in Guerrero. The earthquake's epicenter is Iguala, the state's third largest city.

Fifty thousand marchers thronged Mexico City's main avenues last Wednesday, and demonstrations took place all over the country. More than 80 delegates to the Inter-University Assembly have called for a nationwide halt to all educational activities on Nov. 5, and are asking other social groups to join them. Protesters set fire to state headquarters in Chilpancingo, Guerrero's capital, and are sacking supermarkets and shopping centers.

Here are the events that sparked the earthquake:

On Sept. 26, María de los Ángeles Pineda Villa, wife of Iguala's Mayor José Luis Abarca, of the left-leaning Party of the Democratic Revolution, was in the main square giving a speech about her accomplishments as head of the municipal social services agency, and it was rumored that she would announce her candidacy to succeed her husband as mayor in next June's election, since she is also a state PRD official.

Just as she was beginning, two busloads of students from the notoriously radical rural teachers' college in nearby Ayotzinapa, who had come to town to raise money to supplement their meager 50 peso daily allowance, headed for Iguala's central square. According to the Federal Attorney General's Office, the mayor ordered the local police chief to stop them. After a minor clash with police the students "borrowed" three buses from the local bus station to return to Ayotzinapa and later travel to this year's march in Mexico City commemorating the October 2, 1968 massacre in Tlatelolco, and were driving out of town when they were sprayed with machine gun fire by police and gunmen from the Guerrero Unidos (United Warriors) cartel.

Three students died, as well as a soccer player in a bus bringing a third division team to town that was also fired on, a taxi driver and his female passenger. One student who panicked and ran off when his classmates were rounded up by police and gang members was later found dead, his eyes gouged out and face flensed with a box cutter, in an act of gratuitous violence. Forty-three students were bundled into police cars and have disappeared.

Pineda's family had been working with the Beltrán Leyva, Sinaloa and Guerreros Unidos cartels for years, two of her brothers were gunned down in gang violence, another served time in jail, and a recently captured leader of Guerreros Unidos identified her as "the key operator" of criminal activity in and around Iguala. The Abarcas have not been seen since the mayor hastily requested a leave of absence, and perhaps they are already in one of the burial pits.

Official statements that the 38 bodies found so far in 10 makeshift mass graves are not the students have exacerbated rather than calmed public anger, as now the other question is, who are these trussed up, tortured, headless or charred corpses? Will there be an investigation to find the perpetrators? Or will time be allowed to pass until public indignation subsides, and these cases will join the roughly 98 percent of unsolved homicides in the country that have been swept under a rug as high as the Pico de Orizaba, Mexico's tallest mountain? On Oct. 27, information given by four people arrested early in the day led to the discovery of another clandestine grave holding human remains in the municipal garbage dump in Cocula, whose mayor and police force were arrested two weeks ago.

A month after the Iguala atrocities, officials are bogged down in a quagmire of contradictory information and paralysis in the punishment of those responsible for the disappearance of the 43 students.

The collapse of the PRD in Guerrero, where Angel Aguirre, the governor who migrated from the ruling Institutional Revolutionary Party to the PRD just in time to be elected, has been forced to take an indefinite leave of absence, comes after revelations of multi-million dollar irregularities in the construction of a new subway line in Mexico City during the administration of former PRD mayor Marcelo Ebrard, and ongoing violence in the PRD-governed state of Morelos, where the capital city of Cuernavaca and other towns live under the volcano in a climate of kidnappings and executions at the hands of the Beltran Leyva and Guerrero Unido cartels.

The National Action Party, or PAN, has yet to recover from the stigma it acquired under PAN president Felipe Calderon.

Ten days after taking office on December 1, 2006, Calderon launched a war on drugs which took more than 120,000 lives and left 30,000 persons missing in his six-year-long violence-filled presidency. Government officials claimed that most of the deaths were due to internecine fighting among cartels, or were members of security forces killed in action. However, all too many were innocent victims, in the wrong place at the wrong time, such as the sixteen teenagers gunned down at a party in Ciudad Juarez by a squad of masked gunmen. REMEMBERING EL POZOLERO

This latest episode in the ongoing Mexican horror story brings to mind gruesome brutality during the Calderon presidency, such as "El Pozolero" -- "The Hominy Stewmaker"-- who was charged in 2009 with dissolving the bodies of 300 members of a rival cartel in boiling lye on orders from his boss, or the massacres of undocumented Central and South American migrants making their way to the United States, abducted from buses and raped, tortured and murdered in San Fernando, Tamaulipas by the Los Zetas cartel in reprisal for refusing to work for the cartel or pay a ransom for their release. In 2010, 72 bodies were discovered at a ranch, and a year later 193 were exhumed from mass graves.

A 14-year-old hit man arrested in Cuernavaca -- the youngest yet -- claimed he had tortured and beheaded more than 300 people. Throughout the Calderon years bodies were regularly found hanging from bridges, corpses -- often headless -- or severed heads turned up on city streets, in abandoned vehicles, in shopping centers, on public highways. Threatening messages were usually left with the remains.

In 2011, gunmen set fire to a casino in Monterrey, killing more than 50 people, many of them bingo players, presumably because the owners had refused to make extortion payments. Teachers in several states stopped working in response to threats from gunmen demanding money. In June 2011, U.S. Customs and Border Protection announced that it had arrested more than 100 of its agents since 2004 for collaborating with Mexican cartels. The PAN has yet to recover from its besmirching.

"If (as Goya said) the sleep of reason produces monsters, reason has been in a coma in Mexico."

Two days after the Ayotzinapa tragedy the leader of the PAN in Guerrero was assassinated in an Acapulco restaurant by two disgruntled party members, ostensibly because they weren't given the jobs they wanted.

Not only the PRD and the PAN are in the eye of the storm. Michoacan, which borders on Guerrero and is governed by the ruling Institutional Revolutionary Party (known by its Spanish initials of PRI), came close to being run de facto by the Caballeros Templarios (Knights Templar) cartel, and citizen vigilante groups frustrated by police corruption and inaction took justice into their own hands.

The president appointed a commissioner to take charge and after the governor's son was outed in videos sharing a beer and chatting with La Tuta, the still-at-large leader of the cartel, the governor was replaced by the head of the state university. The vigilantes were disarmed and channeled into an ad hoc rural police, although now dissatisfaction is prompting them to join together anew. Peña Nieto's native State of Mexico, bordering Michoacan, Guerrero and five other states, also suffers from serious problems of criminal violence in towns adjacent to Mexico City, such as Ecatepec. The Military Justice Attorney General has just convicted seven soldiers and a general for involvement in the summary execution of 22 alleged drug traffickers.

With midterm elections coming up on June 15, all three dominant political parties have fallen into disrepute, leaving Mexicans orphaned and without alternatives to purge the country of rampant corruption. The seven smaller parties are largely irrelevant.

PRESIDENT PEÑA NIETO'S REFORMS

Well before Enrique Peña Nieto took office as President on December 1, 2012, it was common knowledge that the main goals of the new PRI government would be to change Mexico's image abroad and to promote foreign investment at home. To avoid legislative deadlock, his operators cobbled together a "Pact for Mexico" by horse-trading with leaders of the main opposition parties, and an ambitious reform package was pushed through Congress.

Sweeping educational reforms -- preceded by the arrest and incarceration of the powerful leader of the principal Mexican teachers' union, who had publicly challenged the president -- were followed by new rules meant to encourage competition in telecommunications, presently controlled by three huge companies. However, the largest and most controversial reform has opened up the energy sector to private and foreign investment, taboo since 1938, when President Lazaro Cardenas expropriated and nationalized all oil reserves and foreign oil companies in Mexico.

For many, one of the most worrisome aspects of energy reform is the possibility that privately owned land can be expropriated for oil and gas exploration. The reform may be challenged in a referendum called for by millions of citizens, after the courts rule on its legality.

The self-congratulatory euphoria following passage of the reforms brought to mind former President José Lopez Portillo's boast of "Fellow Mexicans, we're rich", after vast oil reserves were discovered in the Gulf of Mexico in 1978, ushering in several corruption-ridden boom years.

During the past two years a string of drug kingpins has been arrested or killed, but successors waiting in the wings quickly take their place, or control of turf shifts to other groups. The cartels have branched out, supplementing income from the lucrative drug market in the United States, where most of the weapons used by Mexican criminals originate, with extortion and protection rackets and kidnappings.

Peña Nieto put an end to Calderon's practice of parading captured criminals before television cameras, and has toned down media reports of violence. Entire municipal police forces have been disbanded. Nevertheless, every day brings news of clashes, kidnappings, and murders, and clandestine mass graves have been found in Jalisco, Tamaulipas and Veracruz.

Five years ago Ciudad Juarez, on the northern border with the United States, was widely considered Mexico's most dangerous city, but now the center of gravity seems to have shifted to Guerrero, historically one of the most violent states and an incubator of guerrilla insurgencies.

After the recent discoveries in Iguala people suspect that the country may be peppered with burial pits. The Ministry of Foreign Affairs has deluged embassies and consulates with talking points for damage control. A parody of Peña Nieto's "Saving Mexico" Time magazine cover portraying him as the grim reaper has been making the rounds on the Internet.

It would appear that the much-trumpeted Mexican Moment does not belong to the multinational corporations greedy for a share of Mexico's oil, gas and wind energy bounty and major airport, highway and high-speed rail projects. In the current explosive situation, if the citizenry is left bereft of democratic choices to tackle political corruption, we run the risk of another 1968, when student movements put the government against the ropes shortly before the Summer Olympics were to begin in Mexico City, culminating in the massacre at Tlatelolco, when an unknown number of peaceful demonstrators were shot down by government shock troops and more than 1300 arrested.

Today all Mexico resounds with the cry "They took them alive, we want them back alive." If the 43 are ever found, and they are dead (for why and where would their abductors be hiding them?), all hell may break loose. Are the president and his cabinet ready for a major upheaval?

Police, politicians and judges have been bought off or put into office by the cartels. Mexicans are fed up with living in a pervasive state of corruption and impunity. They are losing hope. If (as Goya said) the sleep of reason produces monsters, reason has been in a coma in Mexico. What we desperately need now from Enrique Peña Nieto is a new deal that can be summed up in two words: honesty and justice.

This can be the real Mexican Moment.

Correction: A previous version of this article stated that more than 100 U.S. Customs and Border Protection agents were arrested in a single day in 2011 for collaborating with cartels. While the announcement of these arrests was made in 2011, the number in fact refers to arrests made since 2004 (as of 2011).

Homero Aridjis is a Mexican poet, environmental activist and former ambassador. His seminal work is "1492: The Life and Times of Juan Cabezón of Castile."