Treasure of Khan (Dirk Pitt 19)

A sick feeling struck Gunn in the stomach and he could feel the color drain from his face.

"I knew I should have stayed in Siberia," he muttered.

-42-

DR. MCCAMMON entered the NUMA computer center just as Yaeger hung up the phone to Mongolia. On the opposite side of the console, the holographic image of Max turned toward the marine geologist and smiled. "Good evening, Dr. McCammon," she said. "Working late?"

"Uh, good evening," McCammon replied, not sure if he should feel foolish for conversing with a computerized image. He nervously turned and greeted Yaeger.

"Hello, Hiram. Long day?" he asked, noting that Yaeger was dressed in the same clothes he wore the day before.

"Very," Yaeger replied, suppressing a yawn. "A late request from the boss yesterday kept us busy. We expected to see you hours ago."

"Some unexpected meetings managed to kill most of my day. I understand if you didn't get a chance to retrieve the data from the earthquake center," McCammon offered.

"Nonsense," Yaeger replied, as if insulted. "Max can multitask with the best of them."

"Yes," Max replied. "And at least some of us keep our demeanor in the process."

"We pulled in the data last night," Yaeger continued, ignoring the comment, "and ran your program early this morning. Max," he said, facing the image of his wife, "please print Dr. McCammon a copy of the program results. And while that is running, why don't you give us a verbal overview of your findings."

"Certainly," Max replied. A large laser printer at the side of the room immediately began humming with the printed output while Max chose her words.

"The data received from the National Earthquake Information Center reflected global seismic activity for the last five years, including the two large quakes that just recently struck the Persian Gulf. I ran your software program, which analyzed the two earthquakes, then filtered their key commonalties against the entire database. Interestingly, there were several unique characteristics associated with the two earthquakes."

Max paused for effect, then stepped closer to Yaeger and McCammon before continuing.

"Both events were classified as extremely shallow earthquakes, as their epicenters were less than three kilometers beneath the surface. This compares to most shallow-focus earthquakes, which are typically in the five- to fifteen-kilometer depth range."

"That's a meaningful difference," McCammon said.

"Of less significance, both were tectonic quakes rather than volcanic in origin. And, as you know, both were large quakes, measuring over 7.0 on the Richter scale."

"Isn't that quite rare to have a pair of quakes with that magnitude?" Yaeger asked.

"It's a little unusual but not unheard of," McCammon said. "An earthquake of that size in Los Angeles would capture plenty of attention, but the fact is there is a 7.0 magnitude or greater earthquake occurring on average once a month somewhere around the world. Since they mostly strike in nonpopulated areas or under the sea, we don't hear much about them."

"That is correct," Max said. "Though there is a statistically significant anomaly in that the two quakes of that magnitude struck in such close proximity."

"Any other similarities, Max?" Yaeger asked.

"Yes. Though difficult to quantify, it appears that the damage produced by these earthquakes was not commensurate with their size. Significant structural damage was recorded at both sites, which exceeded the norm for similarly sized earthquakes. The actual damage was more reflective of what an 8.0 magnitude quake would produce."

"The Richter scale is not always an accurate measure of an earthquake's destructive power," McCammon noted, "particularly for shallow-focus events. In this case, we had two shallow quakes that proved highly damaging. The intensity on the ground was likely much higher than the magnitude rating indicated."

Max frowned briefly as she rifled through her databases, then nodded at McCammon.

"You are absolutely correct, Doctor. The primary seismic waves were much smaller in magnitude than the surface waves for both quakes."

"Anything else, Max?" McCammon asked, finally finding a comfort level with the image.

"Yes, one final aspect. In both earthquakes, there was a record of low-magnitude P-waves registering before the actual quake-induced waves occurred."

"Foreshocks, I suppose," McCammon said. "Not at all unusual."

"Will somebody kindly explain all this surface wave and P-wave business?" Yaeger asked tiredly.

Max shook her head. "Must I teach you everything? Elementary seismology. The slippage from a common tectonic earthquake generates three types of seismic energy releases, or shock waves, if you will. The initial wave is called the primary, or P-type wave. It has similar properties to a sound wave, able to travel through solid rock and even the earth's core. A slower and hence secondary wave is called an S-wave. The S-waves are capable of shearing rock sideways to the direction of travel and produce the damaging vertical and horizontal movement of the ground when they reach the earth's surface. As both types of waves approach the surface, they refract to produce additional surface waves, which create the bulk of the shaking that is felt on the ground."